4.5: Writing Process- Making the Personal Public
By the end of this section, you will be able to:
- Develop a writing project through multiple drafts.
- Apply correct genre conventions for structure, paragraphs, tone, and mechanics.
- Write with purposeful shifts in voice, diction, tone, formality, and structure appropriate to personal narratives.
- Proficiently employ cultural and language variations in composition.
- Experience the collaborative and social aspects of writing processes.
- Give and act on productive feedback to works in progress.
Now it’s your turn to put pen to paper and experience the genre through action. Once you choose a moment to write about and begin the narrative process, you may want to rearrange, rewrite, or even omit some parts entirely. The goal is to create a story that not only gets your message across but also creates an emotional connection with your readers.
Summary of Assingment: A Turning Point
Choose an event from your life that has stuck in your memory as a turning point of some sort. Certainly, you can write about major milestones—graduations, achievements, and the like—but consider small moments and events, too: something that someone said to you or that you overheard, a time you got or didn’t get what you wanted, a time you were disappointed, or a time you thought you knew better than a more experienced person. To get the most accurate perspective of the event, go back in time as far as you can so that you think about the event as objectively as possible and know it as a real and meaningful turning point. Write a story about the event, and use narrative techniques to show why the event has become meaningful. Here are some other ideas about possible turning points:
- A changed attitude toward a friend, sibling, or other family member
- A change of major, if that change is a big step away from what you planned to do
- Making or not making the cut for a team or some other group
- Your feelings when you learned something about yourself or someone close to you
- A move from another country to the United States or from another U.S. location to where you are now
- Becoming fluent in another language
- Realizing that a certain behavior either gets you what you want or doesn’t
- Realizing that someone you admire is not so admirable, or vice versa
- Becoming friends with someone you didn’t expect to be friends with
- Facing an illness or crisis and how it changed or didn’t change you
Another Lens. An alternative to writing a first-person narrative about a turning point is to consider writing about the event from the perspective of someone—or something—else. If the story involves another person in addition to yourself, consider making that person the narrator and having them tell the story as they might view it.
Also consider telling your story from an outside observer’s perspective, or even from the perspective of an inanimate object—for example, the pen used to sign a contract. This perspective may be beneficial for exploring your own emotions and may also offer a helpful alternative if including details about your personal life in your story makes you uncomfortable.
Quick Launch: Plot Diagram
Once you have chosen a topic, freewrite for 5 to 10 minutes, considering the following questions:
- Why is this event memorable?
- What conflict did you face?
- What images come to mind when you think of this event?
Then, begin to isolate details to create a plot diagram. Remember, following a plot diagram involves focusing on the building of tension surrounding the conflict in a story and then resolving it in a meaningful way.
Drafting: Conflict, Point of View, Organization, and Reflection
With the skeleton of a plot diagram in mind, freewrite again for 5 to 10 minutes, considering the following questions:
- Why is this event memorable?
- What conflict did you face?
- What images come to mind when you think of this event?
- What do you want to express to your readers about the event?
- What lessons did you learn from the event?
Purpose
Along with your freewrite, consider what message you want to leave with readers. The reason this moment is important to you should be made clear to readers through the development of the story, most often through the conflict and its resolution. Remember that the conflict is the primary problem or obstacle that the main character—most likely you in this personal narrative—faces and must overcome in order to reach a resolution. Conflict in a personal narrative, as in fiction, usually consists of one or more of five main conflict types:
- Character vs. character
- Character vs. self
- Character vs. environment or nature
- Character vs. society
- Character vs. fate or the supernatural
The purpose and theme are shaped by the conflict. Consider the conflict in the Mark Twain excerpt. Twain needs to run a crossing that, at the beginning of the passage, he feels confident to handle. But as the story progresses and Mr. Bixby sends more people to make him nervous, Twain begins to second-guess himself.
But that did the business for me. My imagination began to construct dangers out of nothing, and they multiplied faster than I could keep the run of them. All at once I imagined I saw shoal water ahead! The wave of coward agony that surged through me then came near dislocating every joint in me. All my confidence in that crossing vanished. I seized the bell-rope; dropped it, ashamed; seized it again; dropped it once more; clutched it tremblingly once again, and pulled it so feebly that I could hardly hear the stroke myself.
This conflict not only builds the reader’s interest in the main character’s problem but also helps Twain develop the theme, his message to the reader: you must rely on your knowledge and training rather than second-guess yourself. In this anecdote, the theme is explicitly stated, but more often than not, authors are more subtle, requiring readers to infer themes on the basis of details in the text. The ways in which you craft your conflict and theme will affect its significance to your readers.
To help you organize you work, complete a graphic organizer like Table \(4.1\) as you are able at this point. You may want to revise it later as you write your draft.
| Basic Story Elements | |
| Purpose | |
| Conflict | |
| Main Characters | |
| Theme |
Plot Elements
Now that you have considered your overall message and have a general idea of what you will write about, think of how you will structure your story. You already have diagrammed some of the Mark Twain excerpt and know how plots move along. One idea for organizing the plot of your narrative is to write down individual moments or events on notecards and physically place them on a table to mimic a hands-on plot diagram. You should have a series of events leading to the climax and fewer events that make up the falling action. This method of plot diagramming also helps you identify where holes may turn up in your plan. For example: Is your exposition missing key background information that is necessary for readers to understand the story? Have you created sufficient tension in the lead-up to the climax of your story? Examine your plot diagram to identify where you need more (or perhaps less) detail in your outline. You might notice that the plot diagram is a bit lopsided, skewing left. If it does, then much of your story leads up to the climax, as it should, with fewer words between the climax and resolution.
Most, but not all, personal narratives are written in chronological order; that is, the storyteller follows the sequence of events according to the order in which they occur. However, there are other structures, such as anecdotes told according to theme, through flashbacks, or in reverse chronological order. The order in which you recount events is important in building tension in the story, thus stimulating readers’ curiosity. Seriously consider how each choice that you make will create readers’ engagement and emotional connection to your story as you plan toward the climax.
Exposition
Next, follow your plot diagram to begin writing your narrative. Start with a strong introduction. Try to think of this introductory section as the “hook,” engaging readers so that they want to continue reading. Create the introduction with vivid details or a relatable anecdote. Remember that this section will introduce the main characters, the setting, and the conflict. Here are some suggestions for an opening strategy, all of which should be brief, generally not more than two paragraphs:
- Anecdote related to your story
- Description of one of the characters involved
- Scenario in which you ask readers what they might do in that situation
- Description of a setting in which you found yourself
- Significant dialogue or action that you will explain later
- One or more open-ended questions that relate closely to the theme; avoid yes/no questions
Transitions
As you do in other writing, build your overall structure through transitions —words and phrases you use to move readers through events, ideas, and time. Transitions smooth connections between ideas, clarifying them and making reading easier. In narratives, transitions often indicate the passage of time. They may also introduce new characters or ideas, tie ideas together, or make connections to the larger theme or message.
Transitions may be concrete, as is the one Mark Twain uses: “Well, one matchless summer’s day. . .” This statement clearly establishes the passage of time. But transitions can also be abstract or subtle, helping the author organize ideas and information. More subtle transitions include changes in elements such as tone, voice, point of view, or even setting. Use the plot diagram as an outline, and move from event to event as you draft your narrative. You will have freedom with paragraph length and structure because you will use dialogue and description. Also, some events or characters may require more detail than others. As you write your narrative, use transitions to move readers along until you ultimately resolve the central conflict and tie its resolution to the theme.\
Point of View
Authors have options for narrating a literary work—that is, they can choose from whose point of view they tell the story. In your narrative, you most likely will use the first-person point of view . When a story is told from this point of view, the narrator is a character in the story and tells it as it happens—that is, as the narrator experiences the event. Mark Twain tells his story from the first-person point of view in the excerpt from Life on the Mississippi . The first sentence of that excerpt reads, “Mr. Bixby served me in this fashion once, and for years afterward I used to blush even in my sleep when I thought of it.” Not only do readers understand that the narrator is telling the story, using pronouns such as me and I , but the narrator also describes his feelings (“blush[ing] even in my sleep”) and thoughts. For more information about point of view, see Editing Focus: Characterization and Point of View and Point of View.
Charcters
Characters in a personal narrative are generally real people, at least in part. As the author, you can focus on certain character traits and ignore, minimize, or exaggerate others. In making the people in your narrative come to life, you will likely assign them different ways of behaving and speaking. For example, one character may use long words and speak condescendingly to another. Another character may find conversation difficult and say little, relying on gestures more than words. Still another character might be generous, sympathetic, arrogant, or sneaky. When creating characters, make sure the characters’ language and behavior reflect their characterizations. For more information about characterization, see Editing Focus: Characterization and Point of View.
You can use a web diagram, similar to the one shown in Figure \(4.7\), to keep track of characters’ traits.
Figure \(4.7\) Character web (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license
Setting
Where and when your narrative takes place is an important part of a narrative, as it is in the excerpt from Twain’s story. You may want to describe a setting in detail if it is important in the course of the story, or you may find it a less essential part of the narrative. In either case, the setting must be described to some extent to give the narrative a sense of time and place.
Verb Tense
Choose the tense in which you want to tell your story, and ensure that you stay consistent throughout the narrative. Typically, you will choose between past tense and present tense. Past tense provides a familiar sense of storytelling, as Twain develops in his anecdote: “I looked around, and there stood Mr. Bixby, smiling a bland, sweet smile.” Another option is to tell your story in the present tense , which provides a sense of urgency to the events and allows readers to feel closer to the action. If you are considering using the present tense, try substituting it in the excerpt from Life on the Mississippi . Consider how it sounds and the difficulties you might encounter in using it. Whichever tense you choose, however, the most important thing is to stick to it, changing it only to indicate a change in chronology. For example, if you are narrating in the present tense and want to indicate something that happened at a time before the events of your story, you would change tenses for clarity. Read more about verb tense consistency in Editing Focus: Verb Tense Consistency.
Active vs. Passive Voice
Verbs have two voices: active and passive. In an active-voice sentence structure, the subject performs the action of the verb. In a passive-voice sentence structure, the subject receives the action of the verb. Consider the examples in Table \(4.2\).
| Active Voice | Passive Voice |
| I devoured the silky pudding. | The silky pudding was devoured by me. |
| The teacher will give you directions. | Directions will be given to you by the teacher. |
| The barnacles scraped my skin. | My skin was scraped by the barnacles. |
| The sloth carried her baby on her back. | The baby sloth was carried by its mother on her back. |
| The two presidents are signing the agreement. | The agreement is being signed by the two presidents. |
| A tornado destroyed the neighborhood. | The neighborhood was destroyed by a tornado. |
The meanings in both passive and active voice remain the same, yet their effect is different. In active voice, the message will be clearer and often more convincing. While it is not wrong to write in the passive voice on occasion, you will usually strengthen your writing by focusing on how a subject performs an action rather removing it from the direct action. For more information about active and passive voice, see Clear and Effective Sentences.
Imagery
In personal narratives and memoirs, imagery not only brings the experience to life but also engages readers through their senses. For example, Twain appeals to the sense of hearing when he describes “the leadsman’s sepulchral cry:—‘D-e-e-p four!’” The use of figurative language, such as similes, metaphors, hyperbole, or personification, often enhances these descriptions. Think of images and figurative language as ways of showing versus telling . Consider Twain’s recounting of the moment he loses his nerve: “I began to climb the wheel like a squirrel.” Certainly, he could have said instead, “I spun the wheel back and forth.” But the use of figurative language, in this case a simile comparing his action to a squirrel’s, helps readers imagine and share Twain’s terror as if they are experiencing the event in the same way. Within a scene in your story, choose an event, moment, or place, and practice using imagery to describe it. Then use a graphic organizer like Figure \(4.8\) to imagine how you might use each sense to describe the same event or another event, moment, or place from your story.
Figure \(4.8\). Senses chart (CC BY 4.0; Rice University & OpenStax)
For your narrative, you do not have to use all the descriptions in the graphic organizer, and doing so would likely clutter your story. Choose the best, most powerful details to enhance your writing and help readers viscerally experience the event, moment, or place.
Sentence Structure
You can structure your text in various ways to achieve your intended mood, tone, and overall message. No matter what your form or style, sentences are your main units of composition, explaining the world in terms of subjects, actions, and objects: some force (a subject) does something (action) that causes something else to happen (an object). Narrative writing, like all prose, is built around complete and predictable sentences.
Sometimes, however, writers use sentences in less predictable and more playful ways. For example, fragmented sentences suggest fragmented stories. Fragmented sentences can be used judiciously in conventional writing, even academic writing, as long as their purpose is clear and your fragment is not mistaken for a grammatical error. Writers sometimes use fragments audaciously and sometimes with abandon to create the special effects they want: A flash of movement. A bit of a story. A frozen scene .
Fragments force quick reading, ask for impressionistic understanding, and suggest parts rather than wholes. Like snapshots, fragments invite strong reader participation to stitch information together and move toward clear meaning. Fragmented sentences suggest, too, that things are moving fast. Often used in dialogue as well to mimic real speech, purposeful fragments can be powerful: Deliberate. Intentional. Careful. Functional. Usually brief .
Consider British novelist Charles Dickens’s (1812–1870) use of fragments in this story told in The Pickwick Papers (1836). The impact of the sentence fragments here conveys a sensory experience and creates a mood for the reader.
“Heads, heads—take care of your heads!” cried the loquacious stranger, as they came out under the low archway, which in those days formed the entrance to the coach-yard. “Terrible place—dangerous work—other day—five children—mother—tall lady, eating sandwiches—forgot the arch—crash—knock—children look round—mother’s head off—sandwich in her hand—no mouth to put it in—head of a family off—shocking, shocking!”
On the opposite pole of sentence structure are labyrinthine sentences . A labyrinthine sentence seems never to end. Instead, it goes on and on and on, using all sorts of punctuational and grammatical tricks to create a compound sentence (two or more independent clauses joined by a comma and a conjunction such as and , or , or but ) or a complex sentence (one independent clause with one or more dependent clauses). Such sentences are often written to suggest that events or time are running together and hard to separate. However, such writing may more often suggest error than experiment, so be careful.
Another type of sentence variation is achieved through repetition of words, phrases, or sentences for emphasis. Repeated words and ideas suggest continuity of idea and theme, help meld ideas and paragraphs, and sometimes create rhythms that are pleasing to the ear. While refrain is a term more often associated with music, poetry, and sermons, it is a form of repetition that is quite powerful in prose as well. A refrain is a phrase or group of words repeated throughout a text to remind readers (or listeners) of an important theme. For example, the words “I have a dream” are a refrain from American activist Martin Luther King Jr. ’s (1929–1968) speech by the same name. Look at how Mark Twain uses repetition to increase the tension.
I seized the bell-rope; dropped it, ashamed; seized it again; dropped it once more; clutched it tremblingly once again, and pulled it so feebly that I could hardly hear the stroke myself.
Variation in sentence structure, established through such techniques as fragments, labyrinthine sentences, and repetition, creates certain effects within the text because each technique conveys its information in an unmistakable way. These techniques are stylistic devices that add an emotional dimension to the typically factual material of narrative prose without announcing, labeling, or dictating what those emotions should be. The wordplay of alternate-style composing allows narrative prose to convey themes more often conveyed through more obviously poetic forms.  For more information about sentence structure, see Clear and Effective Sentences.
Voice
As you write, focus on developing your voice , which in writing is the identity or personality of the narrator or writer. A writer’s voice is sometimes equated with an individual’s personal style—the elements that contribute to the way that person looks and acts. Do you favor certain kinds of clothing? Do you walk in a certain way? Do you have certain characteristic gestures or speech patterns?  In personal writing, voice comes through via narration, dialogue, and characterization and the way you project your personality through them.
Further, writers often speak with more than one voice, or maybe with a single voice that has a wide range, varied registers, multiple tones, and different pitches. In any given composition, a writer may try to say two things at the same time. Sometimes writers question their own assertions, sometimes they say one thing aloud and think another silently to themselves, sometimes they say one thing that means two things, and sometimes they express contradictions, paradoxes, or conundrums.
Double voices in a text may be indicated by parentheses—the equivalent of an actor speaking an aside on the stage or in a film. In a film, the internal monologue of a character may be revealed as a voice-over or through printed subtitles while another reaction is happening on-screen. With text, you can change the type size or font or switch to italic , boldface , or CAPITAL LETTERS to signal a switch in your voice as a writer. The double voice can also occur without distinguishing markers at all or with simple paragraph breaks or spaces.
Effective voice can be achieved through sentence structure and word choices. Try to balance descriptive language and dialogue . You likely have heard the expression “Show, don’t tell.” Use narration to describe events, actions, and even the narrator’s thoughts, but don’t fall into the trap of feeling as though you need to describe everything . Allow events to flow naturally through the narration, weaving in action and dialogue. Precisely placed dialogue can reinforce the narration.
Because voice infuses personality into the composition, the lack of voice or a weak voice may make your story read like a timeline rather than selected events leading to a meaningful turning point. You want your voice to be consistent, reliable, and relatable to your readers. Often this voice will sound like you, infusing your personality or identity into the text. If you recreate authentic (or a good imitation of authentic) dialogue, narration, and description, your voice will likely be strongest, as it suggests a real connection with you.
Mood
When expressing the narrator’s emotions and point of view about the events of the text, voice is a major factor in creating mood (atmosphere). For example, a mood may be gloomy, happy, or tense. The same event told by a narrator with a casual, lighthearted voice can be read completely differently if narrated with a formal, argumentative voice. Consider these two sentences and the effect created by the word choice:
- The rain danced on the pavement, sparkling droplets falling from cotton balls above.
- The rain pounded the pavement, pouring buckets from thundering gray clouds above.
The mood in the first sentence reflects a positive disposition toward the rain. The second sentence, though it says nearly the same thing, shows a negative attitude, expressing the violence of the rain. The two distinct moods, developed through imagery, details, and language, influence the reader’s perception of the rain.
Conclusion and Reflection
At the end of your story, you will have the opportunity to reflect on the turning-point event, its impact on you, and perhaps its application to a universal theme. In the Twain example, the reflection is relatively straightforward.
“Very well, then. You shouldn’t have allowed me or anybody else to shake your confidence in that knowledge. Try to remember that. And another thing: when you get into a dangerous place, don’t turn coward. That isn’t going to help matters any.”
It was a good enough lesson, but pretty hardly learned. Yet about the hardest part of it was that for months I so often had to hear a phrase which I had conceived a particular distaste for. It was, “Oh, Ben, if you love me, back her!”
Twain uses Mr. Bixby’s words to teach both himself and readers the lesson. Twain’s reflection also points to a universal lesson, creating a relatable thread from which readers can learn. As you compose your reflection, ask yourself these questions:
- What have you learned from your turning point?
- What can readers learn from your turning point?
- How will you express this lesson?
You may reflect by using literary elements such as imagery or figurative language that help develop the theme or message. You will want to leave room for your readers’ own interpretations so that they can apply the lesson to their own lives, as Twain does. Certainly, most people have doubted their knowledge and abilities at some point, and Mr. Bixby’s directive “Don’t turn coward” has universal meaning.
Peer Review: Focus on Big-Picture Elements
After your first draft is complete, begin the process of peer review. In this initial review, peer reviewers should focus on big-picture elements, such as plot, point of view, organization, and reflection. Peer reviewers can use the following sentence starters to assess these elements.
- My first impression of the story is _________. From it, I learned _________.
- The story begins with/by _________. It could be made more engaging by _________.
- The author uses dialogue to _________.
- The narrative is organized by _________. Doing _________ could strengthen the organization.
- The author’s main point is _________ and is developed by _________.
- The author wants to tell me _________.
- I think these details could be made stronger to better develop the main idea or theme of _________.
In addition, peer reviewers may choose to mark the manuscript in the following ways:
- Circle unnecessary details. Underline places where more vivid details would bring events or ideas to life.
- Mark places where transitions are needed.
- Place quotation marks in the margin to indicate places where dialogue might better develop the story.
Revising: Let the Small Stuff Go for Now
After reading through your peer review, you now have the opportunity to revise your story. When you revising , reimagine your manuscript until it reaches your audience in the way you want it to. Begin this process by identifying the physical changes you want to make. These might include moving, adding, or deleting content and rewriting ideas. There are also nonphysical ways to revise. Focus on the big picture; think about whether the way you have told your story has delivered your intended message effectively. Avoid getting caught up in minute details before you have shaped the narrative to relate your intended ideas.
Use the following checklist to work through the revision process.
- Introduction: Does the introduction hook the reader and establish the background knowledge needed, including plot and setting?
- Sequence of events: Is the story told in a logical and consistent order?
- Vivid details: Do you provide vivid details that engage your readers’ senses?
- Tone and mood: Are the tone and mood effective for your purpose?
- Characterization, narration, and voice: Have you developed consistent and specific characterization through your narration and voice?
- Dialogue: Does the dialogue help move the plot and reflect the characters?
- Transitions: Have you used clear transitions and time signals to establish chronology and connect important ideas?
- Structure: Have you developed a cohesive structure, including varying sentence lengths and structures? Can you improve sentences by restructuring, combining, or separating them?
- Conclusion: Does your conclusion clearly explain the significance of the turning-point event, including its relationship to the theme you want to develop?


1.1: The Study of Economics
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The Magic of the Economy
The study of economics makes individuals cognizant of their environment and better decision makers.
Learning objectives
Explain how the study of economics provides knowledge to understand the system and policies that guide life.
Economics is a social science. This means that economics has two important attributes. Economics studies human activities and constructions in environments with scarce resources, and uses the scientific method and empirical evidence to build its base of knowledge.
The evaluation of human interactions as it relates to preferences, decision making, and constraints is a significant foundation of economic theory. The complexity of the dynamics of human motivation and systems has led to the establishment of assumptions that form the basis of the theory of consumer and firm behavior, both of which are used to model circular flow interactions within the economy.
Economics provides distilled frameworks to analyze complex societal interactions, as in the case of consumer and firm behavior. An understanding of how wages and consumption flow between consumers and producers provides agents with an ability to understand the symbiosis of the relationship rather than fixating on the contentious components that surface from time to time.
Economics also allows individual agents to balance expectations. An understanding of the ebb and flow of the economy through the boom and bust of the business cycles, creates the potential for emotional balance by reminding agents to limit desperation in downturns and exuberance in expansions.
By developing an understanding of the foundations of economics, individuals can become better decision makers with respect to their own lives and maintain a balance with respect to an externality that has the potential to supplement or deter their plans. Since economic theories are a basis of decision making and regulatory policy, being knowledgable about economics foundations allows an individual to be an active and aware participant rather than a passive economic agent.
Is Economics a Science?
Economics is a social science that has diverse applications.
Learning objectives
Explain how economic theory and analysis can be applied throughout society
Economics is a social science that assesses the relationship between the consumption and production of goods and services in an environment of finite resources. A focus of the subject is how economic agents behave or interact both individually (microeconomics) and in aggregate (macroeconomics).
Microeconomics examines the behavior individual consumers and firms within the market, including assessment of the role of preferences and constraints. Macroeconomics analyzes the entire economy and the issues affecting it. Primary focus areas are unemployment, inflation, economic growth, and monetary and fiscal policy.
The discipline of economics evolved in the mid-19th century through the combination of political economy, social science and philosophy and gained entrenchment with the increased scrutiny of the asymmetric financial and welfare distribution attributed to sovereign rule. Early writings are attributable to Jeremy Bentham, David Ricardo, John Stuart Mill and his son John Mill and are focused on human welfare and benefits rather than capitalism and free markets.
Founders of Economics : John Stuart Mill, along with David Ricardo, Jeremy Bentham and other political and social philosophers of the mid-nineteenth century are credited with the founding of the social-political theory that has evolved to be the discipline of economics.
As in other social sciences, economics does incorporate mathematics in the theoretical and analytics framework of the discipline. Formal economic modeling began in the 19th century with the use of differential calculus to represent and explain economic behavior, such as utility maximization, an early economic application of mathematical optimization in microeconomics. Economics utilizes mathematics to assess the relationships between economic actors in environments in which resources are finite.
The use of mathematics in economics increased the quantitative analysis inherent in the discipline; however, given the discipline’s essentially social science roots, many economists from John Maynard Keynes to Robert Heilbroner and others criticized the broad use of mathematical models for human behavior, arguing that some human choices can not be modeled or evaluated in a mathematical equation.
Economic theory and analysis may be applied throughout society, including business, finance, health care, and government. The underlying components of economic theory can also be applied to variety of other subjects, such as crime, education, the family, law, politics, religion, social institutions, war, and science.
Key Points
- Economics also allows individual agents to balance expectations.
- Economics provides distilled frameworks to analyze complex societal interactions, as in the case of consumer and firm behavior.
- Being knowledgable about economics foundations allows an individual to be an active and aware participant rather than a passive economic agent.
- Economics incorporates both qualitative and quantitative assessment.
- Economics is divided into two broad areas: microeconomics and macroeconomics.
- Economics can be applied throughout society from business to individual behavior with further application in the study of crime, family and other social institutions and interactions.
Key Terms
- externality : An impact, positive or negative, on any party not involved in a given economic transaction or act.
- circular flow : A model of market economy that shows the flow of dollars between households and firms.
- social science : A branch of science that studies the society and human behavior in it, including anthropology, communication studies, criminology, economics, geography, history, political science, psychology, social studies, and sociology.
LICENSES AND ATTRIBUTIONS
CC LICENSED CONTENT, SPECIFIC ATTRIBUTION
- Circular flow of income. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Circular_flow_of_income . License : CC BY-SA: Attribution-ShareAlike
- Principles of Economics/What Is Economics. Provided by : Wikibooks. Located at : en.wikibooks.org/wiki/Princip...t_Is_Economics . License : CC BY-SA: Attribution-ShareAlike
- externality. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/externality . License : CC BY-SA: Attribution-ShareAlike
- Boundless. Provided by : Boundless Learning. Located at : www.boundless.com//economics/.../circular-flow . License : CC BY-SA: Attribution-ShareAlike
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- social science. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/social_science . License : CC BY-SA: Attribution-ShareAlike
- Economics. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Economics . License : CC BY-SA: Attribution-ShareAlike
- Mathematical economics. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Mathematical_economics . License : CC BY-SA: Attribution-ShareAlike
- John Stuart Mill. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/John_Stuart_Mill . License : CC BY-SA: Attribution-ShareAlike
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7.1: Why It Matters- Microsoft Excel Intermediate Skills
Why learn to complete intermediate skills in Microsoft Excel?
In the last module, we focused on some basic functionality in Excel. But this program is capable of a lot more, including automatically organizing data (known as Sort), hiding data (Filter), and even more advanced functions that will automatically format cells visually if they meet certain conditions.
Before we move into the mechanics of each of these tools, let us consider for a moment the types of questions you may have when looking at data in an Excel worksheet.
- You want to see which month had your highest sales volume.
- You have a total clothing inventory but you want to know how many pants you have in stock.
- You want to know how many months from last year you were under budget.
- You want to see a graphic that represents your data instead of the actual numbers.
All of these questions can be answered with the valuable tools available in Excel and most importantly, without manually looking through all of your data!
Contributors and Attributions
- Why It Matters: Microsoft Excel Intermediate Skills. Authored by : Shelli Carter. Provided by : Lumen Learning. License : CC BY: Attribution


18.10: Occurrence, Preparation, and Compounds of Oxygen
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Learning Objectives
By the end of this section, you will be able to:
- Describe the properties, preparation, and compounds of oxygen
- Describe the preparation, properties, and uses of some representative metal oxides, peroxides, and hydroxides
Oxygen is the most abundant element on the earth’s crust. The earth’s surface is composed of the crust, atmosphere, and hydrosphere. About 50% of the mass of the earth’s crust consists of oxygen (combined with other elements, principally silicon). Oxygen occurs as O 2 molecules and, to a limited extent, as O 3 (ozone) molecules in air. It forms about 20% of the mass of the air. About 89% of water by mass consists of combined oxygen. In combination with carbon, hydrogen, and nitrogen, oxygen is a large part of plants and animals.
Oxygen is a colorless, odorless, and tasteless gas at ordinary temperatures. It is slightly denser than air. Although it is only slightly soluble in water (49 mL of gas dissolves in 1 L at STP), oxygen’s solubility is very important to aquatic life.
Most of the oxygen isolated commercially comes from air and the remainder from the electrolysis of water. The separation of oxygen from air begins with cooling and compressing the air until it liquefies. As liquid air warms, oxygen with its higher boiling point (90 K) separates from nitrogen, which has a lower boiling point (77 K). It is possible to separate the other components of air at the same time based on differences in their boiling points.
Oxygen is essential in combustion processes such as the burning of fuels. Plants and animals use the oxygen from the air in respiration. The administration of oxygen-enriched air is an important medical practice when a patient is receiving an inadequate supply of oxygen because of shock, pneumonia, or some other illness.
The chemical industry employs oxygen for oxidizing many substances. A significant amount of oxygen produced commercially is important in the removal of carbon from iron during steel production. Large quantities of pure oxygen are also necessary in metal fabrication and in the cutting and welding of metals with oxyhydrogen and oxyacetylene torches.
Liquid oxygen is important to the space industry. It is an oxidizing agent in rocket engines. It is also the source of gaseous oxygen for life support in space.
As we know, oxygen is very important to life. The energy required for the maintenance of normal body functions in human beings and in other organisms comes from the slow oxidation of chemical compounds. Oxygen is the final oxidizing agent in these reactions. In humans, oxygen passes from the lungs into the blood, where it combines with hemoglobin, producing oxyhemoglobin. In this form, blood transports the oxygen to tissues, where it is transferred to the tissues. The ultimate products are carbon dioxide and water. The blood carries the carbon dioxide through the veins to the lungs, where the blood releases the carbon dioxide and collects another supply of oxygen. Digestion and assimilation of food regenerate the materials consumed by oxidation in the body; the energy liberated is the same as if the food burned outside the body.
Green plants continually replenish the oxygen in the atmosphere by a process called photosynthesis . The products of photosynthesis may vary, but, in general, the process converts carbon dioxide and water into glucose (a sugar) and oxygen using the energy of light:
\[\underset{\text{carbon} \\[4pt][4pt]\text{dioxide}}{\ce{6 CO2(g)}} + \underset{\text{water}}{\ce{6 H2O(l)}} \ce{->[\text{chlorophyll}][\text{light}]} \underset{\text{glucose}}{\ce{C6H12O6(aq)}} + \underset{\text{oxygen}}{\ce{6O2(g)}} \nonumber \]
Thus, the oxygen that became carbon dioxide and water by the metabolic processes in plants and animals returns to the atmosphere by photosynthesis.
When dry oxygen is passed between two electrically charged plates, ozone (O 3 , illustrated in Figure \(\PageIndex{1}\)), an allotrope of oxygen possessing a distinctive odor, forms. The formation of ozone from oxygen is an endothermic reaction, in which the energy comes from an electrical discharge, heat, or ultraviolet light:
\[\ce{3 O2(g) ->[\text { electric discharge }] O3(g)} \quad \quad \Delta H^{\circ}=287~\text{kJ} \nonumber \]
The sharp odor associated with sparking electrical equipment is due, in part, to ozone.
Ozone forms naturally in the upper atmosphere by the action of ultraviolet light from the sun on the oxygen there. Most atmospheric ozone occurs in the stratosphere, a layer of the atmosphere extending from about 10 to 50 kilometers above the earth’s surface. This ozone acts as a barrier to harmful ultraviolet light from the sun by absorbing it via a chemical decomposition reaction:
\[\ce{O3(g) ->[\text{ultraviolet light}] O(g) + O2(g)} \nonumber \]
The reactive oxygen atoms recombine with molecular oxygen to complete the ozone cycle. The presence of stratospheric ozone decreases the frequency of skin cancer and other damaging effects of ultraviolet radiation. It has been clearly demonstrated that chlorofluorocarbons, CFCs (known commercially as Freons), which were present as aerosol propellants in spray cans and as refrigerants, caused depletion of ozone in the stratosphere. This occurred because ultraviolet light also causes CFCs to decompose, producing atomic chlorine. The chlorine atoms react with ozone molecules, resulting in a net removal of O 3 molecules from stratosphere. This process is explored in detail in our coverage of chemical kinetics. There is a worldwide effort to reduce the amount of CFCs used commercially, and the ozone hole is already beginning to decrease in size as atmospheric concentrations of atomic chlorine decrease. While ozone in the stratosphere helps protect us, ozone in the troposphere is a problem. This ozone is a toxic component of photochemical smog.
The uses of ozone depend on its reactivity with other substances. It can be used as a bleaching agent for oils, waxes, fabrics, and starch: It oxidizes the colored compounds in these substances to colorless compounds. It is an alternative to chlorine as a disinfectant for water.
Reactions
Elemental oxygen is a strong oxidizing agent. It reacts with most other elements and many compounds.
Reaction with Elements
Oxygen reacts directly at room temperature or at elevated temperatures with all other elements except the noble gases, the halogens, and few second- and third-row transition metals of low reactivity (those with higher reduction potentials than copper). Rust is an example of the reaction of oxygen with iron. The more active metals form peroxides or superoxides. Less active metals and the nonmetals give oxides. Two examples of these reactions are:
\[\begin{align*}
\ce{2 Mg(s) + O_2(g) &\longrightarrow 2 MgO(s)} \\[4pt][4pt]
\ce{P_4(s) + 5 O_2(g) &\longrightarrow P4O10(s)}
\end{align*} \]
The oxides of halogens, at least one of the noble gases, and metals with higher reduction potentials than copper do not form by the direct action of the elements with oxygen.
Reaction with Compounds
Elemental oxygen also reacts with some compounds. If it is possible to oxidize any of the elements in a given compound, further oxidation by oxygen can occur. For example, hydrogen sulfide, H 2 S, contains sulfur with an oxidation state of 2−. Because the sulfur does not exhibit its maximum oxidation state, we would expect H 2 S to react with oxygen. It does, yielding water and sulfur dioxide. The reaction is:
\[\ce{2 H2S(g) + 3O2(g) \longrightarrow 2 H2O(l) + 2 SO2(g)} \nonumber \]
It is also possible to oxidize oxides such as CO and P 4 O 6 that contain an element with a lower oxidation state. The ease with which elemental oxygen picks up electrons is mirrored by the difficulty of removing electrons from oxygen in most oxides. Of the elements, only the very reactive fluorine can oxidize oxides to form oxygen gas.
Oxides, Peroxides, and Hydroxides
Compounds of the representative metals with oxygen fall into three categories:
- oxides containing oxide ions, \(\ce{O^{2−}}\),
- peroxides containing peroxides ions, \(\ce{O_2^{2−}}\) with oxygen-oxygen covalent single bonds and a very limited number of superoxides , containing superoxide ions, \(\ce{O_2^{−}}\) with oxygen-oxygen covalent bonds that have a bond order of \(\frac{3}{2}\),
- hydroxides containing hydroxide ions, \(\ce{OH^{−}}\). All representative metals form oxides. Some of the metals of group 2 also form peroxides, \(\ce{MO2}\), and the metals of group 1 also form peroxides, \(\ce{M2O2}\), and superoxides, \(\ce{MO2}\).
Oxides
It is possible to produce the oxides of most representative metals by heating the corresponding hydroxides (forming the oxide and gaseous water) or carbonates (forming the oxide and gaseous CO 2 ). Equations for example reactions are:
\[\begin{align*}
\ce{2 Al(OH)3(s) ->[\Delta] Al2O3(s) + 3 H2O(g)} \\[4pt][4pt]
\ce{CaCO3(s) ->[\Delta] CaO(s) + CO2(g)}
\end{align*} \nonumber \]
However, alkali metal salts generally are very stable and do not decompose easily when heated. Alkali metal oxides result from the oxidation-reduction reactions created by heating nitrates or hydroxides with the metals. Equations for sample reactions are:
\[\begin{align*}
\ce{2 KNO3(s) + 10 K(s) ->[\Delta] 6 K_2O(s) + N2(g)} \\[4pt][4pt]
\ce{2 LiOH(s) + 2 Li(s) ->[\Delta] 2 Li2O(s) + H2(g)}
\end{align*} \nonumber \]
With the exception of mercury(II) oxide, it is possible to produce the oxides of the metals of groups 2–15 by burning the corresponding metal in air. The heaviest member of each group, the member for which the inert pair effect is most pronounced, forms an oxide in which the oxidation state of the metal ion is two less than the group oxidation state (inert pair effect). Thus, Tl 2 O, PbO, and Bi 2 O 3 form when burning thallium, lead, and bismuth, respectively. The oxides of the lighter members of each group exhibit the group oxidation state. For example, SnO 2 forms from burning tin. Mercury(II) oxide, HgO, forms slowly when mercury is warmed below 500 °C; it decomposes at higher temperatures.
Burning the members of groups 1 and 2 in air is not a suitable way to form the oxides of these elements. These metals are reactive enough to combine with nitrogen in the air, so they form mixtures of oxides and ionic nitrides. Several also form peroxides or superoxides when heated in air.
Ionic oxides all contain the oxide ion, a very powerful hydrogen ion acceptor. With the exception of the very insoluble aluminum oxide, Al 2 O 3 , tin(IV), SnO 2 , and lead(IV), PbO 2 , the oxides of the representative metals react with acids to form salts. Some equations for these reactions are:
\[\begin{align*}
\ce{Na2O + 2 HNO3(aq) &-> 2 NaNO3(aq) + H2O(l)} \\[4pt][4pt]
\ce{CaO(s) + 2 HCl(aq) & -> CaCl2(aq) + H2O(l)} \\[4pt][4pt]
\ce{SnO(s) + 2 HClO4(aq) & -> Sn(ClO4)2(aq) + H2O(l)}
\end{align*} \nonumber \]
The oxides of the metals of groups 1 and 2 and of thallium(I) oxide react with water and form hydroxides. Examples of such reactions are:
\[\begin{align*}
\ce{Na2O(s) + H2O(l) \longrightarrow NaOH(aq)} \\[4pt][4pt]
\ce{CaO(s) + H2O(l) \longrightarrow Ca(OH)2(aq)} \\[4pt][4pt]
\ce{Tl2O(s) + H2O(aq) \longrightarrow 2 TlOH(aq)}
\end{align*} \nonumber \]
The oxides of the alkali metals have little industrial utility, unlike magnesium oxide, calcium oxide, and aluminum oxide. Magnesium oxide is important in making firebrick, crucibles, furnace linings, and thermal insulation—applications that require chemical and thermal stability. Calcium oxide, sometimes called quicklime or lime in the industrial market, is very reactive, and its principal uses reflect its reactivity. Pure calcium oxide emits an intense white light when heated to a high temperature (as illustrated in Figure \(\PageIndex{2}\)). Blocks of calcium oxide heated by gas flames were the stage lights in theaters before electricity was available. This is the source of the phrase “in the limelight.”
Calcium oxide and calcium hydroxide are inexpensive bases used extensively in chemical processing, although most of the useful products prepared from them do not contain calcium. Calcium oxide, CaO, is made by heating calcium carbonate, CaCO 3 , which is widely and inexpensively available as limestone or oyster shells:
\[\ce{CaCO_3(s) \longrightarrow CaO(s) + CO_2(g)} \nonumber \]
Although this decomposition reaction is reversible, it is possible to obtain a 100% yield of CaO by allowing the CO 2 to escape. It is possible to prepare calcium hydroxide by the familiar acid-base reaction of a soluble metal oxide with water:
\[\ce{CaO(s) + H2O(l) \longrightarrow Ca(OH)_2(s)} \nonumber \]
Both CaO and Ca(OH) 2 are useful as bases; they accept protons and neutralize acids.
Alumina (Al 2 O 3 ) occurs in nature as the mineral corundum, a very hard substance used as an abrasive for grinding and polishing. Corundum is important to the jewelry trade as ruby and sapphire. The color of ruby is due to the presence of a small amount of chromium; other impurities produce the wide variety of colors possible for sapphires. Artificial rubies and sapphires are now manufactured by melting aluminum oxide (melting point = 2050 °C) with small amounts of oxides to produce the desired colors and cooling the melt in such a way as to produce large crystals. Ruby lasers use synthetic ruby crystals.
Zinc oxide, ZnO, was a useful white paint pigment; however, pollutants tend to discolor the compound. The compound is also important in the manufacture of automobile tires and other rubber goods, and in the preparation of medicinal ointments. For example, zinc-oxide-based sunscreens, as shown in Figure \(\PageIndex{3}\), help prevent sunburn. The zinc oxide in these sunscreens is present in the form of very small grains known as nanoparticles. Lead dioxide is a constituent of charged lead storage batteries. Lead(IV) tends to revert to the more stable lead(II) ion by gaining two electrons, so lead dioxide is a powerful oxidizing agent.
Peroxides and Superoxides
Peroxides and superoxides are strong oxidizers and are important in chemical processes. Hydrogen peroxide, H 2 O 2 , prepared from metal peroxides, is an important bleach and disinfectant. Peroxides and superoxides form when the metal or metal oxides of groups 1 and 2 react with pure oxygen at elevated temperatures. Sodium peroxide and the peroxides of calcium, strontium, and barium form by heating the corresponding metal or metal oxide in pure oxygen:
\[\begin{align*}
\ce{2 Na(s) + O_2(g) ->[\Delta] Na2O2(s)} \\[4pt][4pt]
\ce{2 Na2O(s) + O_2(g) ->[\Delta] 2 Na2O2(s)} \\[4pt][4pt]
\ce{2 SrO(s) + O2(g) ->[\Delta] 2 SrO2(s)}
\end{align*} \]
The peroxides of potassium, rubidium, and cesium can be prepared by heating the metal or its oxide in a carefully controlled amount of oxygen:
\[\ce{2 K(s) + O_2(g) \longrightarrow K2O2(s)} \quad \quad (2~\text{mol}~\ce{K} \text { per mol} ~\ce{O2}) \nonumber \]
With an excess of oxygen, the superoxides KO 2 , RbO 2 , and CsO 2 form. For example:
\[\ce{K(s) + O2(g) \longrightarrow KO2(s)} \quad \quad (1 ~\text{mol} ~\ce{K} \text { per mol} ~\ce{O2}) \nonumber \]
The stability of the peroxides and superoxides of the alkali metals increases as the size of the cation increases.
Hydroxides
Hydroxides are compounds that contain the OH − ion. It is possible to prepare these compounds by two general types of reactions. Soluble metal hydroxides can be produced by the reaction of the metal or metal oxide with water. Insoluble metal hydroxides form when a solution of a soluble salt of the metal combines with a solution containing hydroxide ions.
With the exception of beryllium and magnesium, the metals of groups 1 and 2 react with water to form hydroxides and hydrogen gas. Examples of such reactions include:
\[\begin{align*}
\ce{2 Li(s) + 2 H2O(l) \longrightarrow 2 LiOH(aq) + H_2(g)} \\[4pt][4pt]
\ce{Ca(s) + 2 H2O(l) \longrightarrow Ca ( OH )_2(aq) + H_2(g)}
\end{align*} \]
However, these reactions can be violent and dangerous; therefore, it is preferable to produce soluble metal hydroxides by the reaction of the respective oxide with water:
\[\begin{align*}
\ce{Li_2O(s) + H2O(l) &\longrightarrow 2 LiOH(aq)} \\[4pt][4pt]
\ce{CaO(s) + H2O(l) &\longrightarrow Ca(OH)2(aq)}
\end{align*} \]
Most metal oxides are base anhydrides . This is obvious for the soluble oxides because they form metal hydroxides. Most other metal oxides are insoluble and do not form hydroxides in water; however, they are still base anhydrides because they will react with acids.
It is possible to prepare the insoluble hydroxides of beryllium, magnesium, and other representative metals by the addition of sodium hydroxide to a solution of a salt of the respective metal. The net ionic equations for the reactions involving a magnesium salt, an aluminum salt, and a zinc salt are:
\[\begin{align*}
\ce{Mg^{2+}(aq) + 2 OH^{-}(aq) &\longrightarrow Mg(OH)2(s)} \\[4pt][4pt]
\ce{Al^{3+}(aq) + 3 OH^{-}(aq) &\longrightarrow Al(OH)3(s)} \\[4pt][4pt]
\ce{Zn^{2+}(aq) + 2 OH^{-}(aq) &\longrightarrow Zn(OH)2(s)}
\end{align*} \]
An excess of hydroxide must be avoided when preparing aluminum, gallium, zinc, and tin(II) hydroxides, or the hydroxides will dissolve with the formation of the corresponding complex ions: \(\ce{ Al(OH)4^{−}}\), \(\ce{Ga(OH)4^{−}}\), \(\ce{Zn(OH)4^{2−}}\), and \(\ce{Sn(OH)3^{−}}\) (Figure \(\PageIndex{4}\)). The important aspect of complex ions for this chapter is that they form by a Lewis acid-base reaction with the metal being the Lewis acid.
Industry uses large quantities of sodium hydroxide as a cheap, strong base. Sodium chloride is the starting material for the production of NaOH because NaCl is a less expensive starting material than the oxide. Sodium hydroxide is among the top 10 chemicals in production in the United States, and this production was almost entirely by electrolysis of solutions of sodium chloride. This process is the chlor-alkali process , and it is the primary method for producing chlorine.
Sodium hydroxide is an ionic compound and melts without decomposition. It is very soluble in water, giving off a great deal of heat and forming very basic solutions: 40 grams of sodium hydroxide dissolves in only 60 grams of water at 25 °C. Sodium hydroxide is employed in the production of other sodium compounds and is used to neutralize acidic solutions during the production of other chemicals such as petrochemicals and polymers.
Many of the applications of hydroxides are for the neutralization of acids (such as the antacid shown in Figure \(\PageIndex{5}\)) and for the preparation of oxides by thermal decomposition. An aqueous suspension of magnesium hydroxide constitutes the antacid milk of magnesia. Because of its ready availability (from the reaction of water with calcium oxide prepared by the decomposition of limestone, CaCO 3 ), low cost, and activity, calcium hydroxide is used extensively in commercial applications needing a cheap, strong base. The reaction of hydroxides with appropriate acids is also used to prepare salts.
Chemistry in Everyday Life: The Chlor-Alkali Process
Although they are very different chemically, there is a link between chlorine and sodium hydroxide because there is an important electrochemical process that produces the two chemicals simultaneously. The process known as the chlor-alkali process, utilizes sodium chloride, which occurs in large deposits in many parts of the world. This is an electrochemical process to oxidize chloride ion to chlorine and generate sodium hydroxide.
Passing a direct current of electricity through a solution of NaCl causes the chloride ions to migrate to the positive electrode where oxidation to gaseous chlorine occurs when the ion gives up an electron to the electrode:
\[\ce{2 Cl^{-}(aq) -> Cl_2(g) + 2 e^{-}} \quad \quad \text { (at the positive electrode) } \nonumber \]
The electrons produced travel through the outside electrical circuit to the negative electrode. Although the positive sodium ions migrate toward this negative electrode, metallic sodium does not form because sodium ions are too difficult to reduce under the conditions used. (Recall that metallic sodium is active enough to react with water and hence, even if produced, would immediately react with water to produce sodium ions again.) Instead, water molecules pick up electrons from the electrode and undergo reduction to form hydrogen gas and hydroxide ions:
\[\ce{2 H2O(l)} + \ce{2 e^{-}} (\text{from the negative electrode}) \ce{-> H_2(g) + 2 OH^{-}(aq)} \nonumber \]
The overall result is the conversion of the aqueous solution of NaCl to an aqueous solution of NaOH, gaseous Cl 2 , and gaseous H 2 :
\[\ce{2 Na^{+}(aq) + 2 Cl^{-}(aq) + 2 H2O(l) ->[\text {electrolysis}] 2 Na^{+}(aq) + 2 OH^{-}(aq) + Cl_2(g) + H_2(g)} \nonumber \]
Nonmetal Oxygen Compounds
Most nonmetals react with oxygen to form nonmetal oxides. Depending on the available oxidation states for the element, a variety of oxides might form. Fluorine will combine with oxygen to form fluorides such as OF 2 , where the oxygen has a 2+-oxidation state.
Sulfur Oxygen Compounds
The two common oxides of sulfur are sulfur dioxide, SO 2 , and sulfur trioxide, SO 3 . The odor of burning sulfur comes from sulfur dioxide. Sulfur dioxide, shown in Figure \(\PageIndex{6}\), occurs in volcanic gases and in the atmosphere near industrial plants that burn fuel containing sulfur compounds.
Commercial production of sulfur dioxide is from either burning sulfur or roasting sulfide ores such as ZnS, FeS 2 , and Cu 2 S in air. (Roasting, which forms the metal oxide, is the first step in the separation of many metals from their ores.) A convenient method for preparing sulfur dioxide in the laboratory is by the action of a strong acid on either sulfite salts containing the \(\ce{SO3^{2-}}\) ion or hydrogen sulfite salts containing \(\ce{HSO3^{-}}\). Sulfurous acid, H 2 SO 3 , forms first, but quickly decomposes into sulfur dioxide and water. Sulfur dioxide also forms when many reducing agents react with hot, concentrated sulfuric acid. Sulfur trioxide forms slowly when heating sulfur dioxide and oxygen together, and the reaction is exothermic:
\[\ce{2 SO2(g) + O2(g) \longrightarrow 2 SO3(g)} \quad \quad \quad \quad \Delta H^{\circ}=-197.8 kJ \nonumber \]
Sulfur dioxide is a gas at room temperature, and the SO 2 molecule is bent. Sulfur trioxide melts at 17 °C and boils at 43 °C. In the vapor state, its molecules are single SO 3 units (shown in Figure \(\PageIndex{7}\)), but in the solid state, SO 3 exists in several polymeric forms.
The sulfur oxides react as Lewis acids with many oxides and hydroxides in Lewis acid-base reactions, with the formation of sulfites or hydrogen sulfites , and sulfates or hydrogen sulfates , respectively.
Halogen Oxygen Compounds
The halogens do not react directly with oxygen, but it is possible to prepare binary oxygen-halogen compounds by the reactions of the halogens with oxygen-containing compounds. Oxygen compounds with chlorine, bromine, and iodine are oxides because oxygen is the more electronegative element in these compounds. On the other hand, fluorine compounds with oxygen are fluorides because fluorine is the more electronegative element.
As a class, the oxides are extremely reactive and unstable, and their chemistry has little practical importance. Dichlorine oxide, formally called dichlorine monoxide, and chlorine dioxide, both shown in Figure \(\PageIndex{8}\), are the only commercially important compounds. They are important as bleaching agents (for use with pulp and flour) and for water treatment.
Nonmetal Oxyacids and Their Salts
Nonmetal oxides form acids when allowed to react with water; these are acid anhydrides. The resulting oxyanions can form salts with various metal ions.
Nitrogen Oxyacids and Salts
Nitrogen pentaoxide, N 2 O 5 , and NO 2 react with water to form nitric acid, HNO 3 . Alchemists, as early as the eighth century, knew nitric acid (shown in Figure \(\PageIndex{9}\)) as aqua fortis (meaning "strong water"). The acid was useful in the separation of gold from silver because it dissolves silver but not gold. Traces of nitric acid occur in the atmosphere after thunderstorms, and its salts are widely distributed in nature. There are tremendous deposits of Chile saltpeter, NaNO 3 , in the desert region near the boundary of Chile and Peru. Bengal saltpeter, KNO 3 , occurs in India and in other countries of the Far East.
In the laboratory, it is possible to produce nitric acid by heating a nitrate salt (such as sodium or potassium nitrate) with concentrated sulfuric acid:
\[\ce{NaNO3(s) + H2SO4(l) ->[\Delta] NaHSO4(s) + HNO3(g)} \nonumber \]
The Ostwald process is the commercial method for producing nitric acid. This process involves the oxidation of ammonia to nitric oxide, NO; oxidation of nitric oxide to nitrogen dioxide, NO 2 ; and further oxidation and hydration of nitrogen dioxide to form nitric acid:
\[\begin{align*}
\ce{4 NH3(g) + 5 O2(g) &\longrightarrow 4 NO(g) + 6 H2O(g)} \\[4pt][4pt]
\ce{2 NO(g) + O2(g) &\longrightarrow 2 NO2(g)} \\[4pt][4pt]
\ce{3 NO2(g) + H2O(l) &\longrightarrow 2 HNO3(aq) + NO(g)}
\end{align*} \]
Or
\[\ce{4 NO_2(g) + O_2(g) + 2 H2O(g) \longrightarrow 4 HNO_3(l)} \nonumber \]
Pure nitric acid is a colorless liquid. However, it is often yellow or brown in color because NO 2 forms as the acid decomposes. Nitric acid is stable in aqueous solution; solutions containing 68% of the acid are commercially available concentrated nitric acid. It is both a strong oxidizing agent and a strong acid.
The action of nitric acid on a metal rarely produces H 2 (by reduction of H + ) in more than small amounts. Instead, the reduction of nitrogen occurs. The products formed depend on the concentration of the acid, the activity of the metal, and the temperature. Normally, a mixture of nitrates, nitrogen oxides, and various reduction products form. Less active metals such as copper, silver, and lead reduce concentrated nitric acid primarily to nitrogen dioxide. The reaction of dilute nitric acid with copper produces NO. In each case, the nitrate salts of the metals crystallize upon evaporation of the resultant solutions.
Nonmetallic elements, such as sulfur, carbon, iodine, and phosphorus, undergo oxidation by concentrated nitric acid to their oxides or oxyacids, with the formation of NO 2 :
\[\begin{align*}
\ce{S(s) + 6 HNO3(aq) &\longrightarrow H2SO4(aq) + 6 NO2(g) + 2 H2O(l)} \\[4pt][4pt]
\ce{C(s) + 4 HNO3(aq) &\longrightarrow CO2(g) + 4 NO2(g) + 2 H2O(l)}
\end{align*} \]
Nitric acid oxidizes many compounds; for example, concentrated nitric acid readily oxidizes hydrochloric acid to chlorine and chlorine dioxide. A mixture of one part concentrated nitric acid and three parts concentrated hydrochloric acid (called aqua regia , which means royal water) reacts vigorously with metals. This mixture is particularly useful in dissolving gold, platinum, and other metals that are more difficult to oxidize than hydrogen. A simplified equation to represent the action of aqua regia on gold is:
\[\ce{Au(s) + 4 HCl(aq) + 3 HNO3(aq) \longrightarrow HAuCl4(aq) + 3 NO2(g) + 3 H2O(l)} \nonumber \]
Link to Learning
Although gold is generally unreactive, you can watch a video of the complex mixture of compounds present in aqua regia dissolving it into solution.
Nitrates , salts of nitric acid, form when metals, oxides, hydroxides, or carbonates react with nitric acid. Most nitrates are soluble in water; indeed, one of the significant uses of nitric acid is to prepare soluble metal nitrates.
Nitric acid finds extensive use in the laboratory and in chemical industries as a strong acid and strong oxidizing agent. It is important in the manufacture of explosives, dyes, plastics, and drugs. Salts of nitric acid (nitrates) are valuable as fertilizers. Gunpowder is a mixture of potassium nitrate, sulfur, and charcoal.
The reaction of N 2 O 3 with water gives a pale blue solution of nitrous acid, HNO 2 . However, HNO 2 (shown in Figure \(\PageIndex{10}\)) is easier to prepare by the addition of an acid to a solution of nitrite; nitrous acid is a weak acid, so the nitrite ion is basic in aqueous solution:
\[\ce{NO_2^{-}(aq) + H3O^{+}(aq) \longrightarrow HNO_2(aq) + H2O(l)} \nonumber \]
Nitrous acid is very unstable and exists only in solution. It disproportionates slowly at room temperature (rapidly when heated) into nitric acid and nitric oxide. Nitrous acid is an active oxidizing agent with strong reducing agents, and strong oxidizing agents oxidize it to nitric acid.
Sodium nitrite, NaNO 2 , is an additive to meats such as hot dogs and cold cuts. The nitrite ion has two functions. It limits the growth of bacteria that can cause food poisoning, and it prolongs the meat’s retention of its red color. The addition of sodium nitrite to meat products is controversial because nitrous acid reacts with certain organic compounds to form a class of compounds known as nitrosamines. Nitrosamines produce cancer in laboratory animals. This has prompted the FDA to limit the amount of NaNO 2 in foods.
The nitrites are much more stable than the acid, but nitrites, like nitrates, can explode. Nitrites, like nitrates, are also soluble in water (AgNO 2 is only slightly soluble).
Phosphorus Oxyacids and Salts
Pure orthophosphoric acid, H 3 PO 4 (shown in Figure \(\PageIndex{11}\)), forms colorless, deliquescent crystals that melt at 42 °C. The common name of this compound is phosphoric acid, and is commercially available as a viscous 82% solution known as syrupy phosphoric acid. One use of phosphoric acid is as an additive to many soft drinks.
One commercial method of preparing orthophosphoric acid is to treat calcium phosphate rock with concentrated sulfuric acid:
\[\ce{Ca_3(PO_4)2(s) + 3 H2SO4(aq) \longrightarrow 2 H3PO4(aq) + 3 CaSO4(s)} \nonumber \]
Dilution of the products with water, followed by filtration to remove calcium sulfate, gives a dilute acid solution contaminated with calcium dihydrogen phosphate, Ca(H 2 PO 4 ) 2 , and other compounds associated with calcium phosphate rock. It is possible to prepare pure orthophosphoric acid by dissolving P 4 O 10 in water.
The action of water on P 4 O 6 , PCl 3 , PBr 3 , or PI 3 forms phosphorous acid, H 3 PO 3 (shown in Figure \(\PageIndex{12}\)). The best method for preparing pure phosphorous acid is by hydrolyzing phosphorus trichloride:
\[\ce{PCl_3(l) + 3 H2O(l) \longrightarrow H_3 PO_3(aq) + 3 HCl(g)} \nonumber \]
Heating the resulting solution expels the hydrogen chloride and leads to the evaporation of water. When sufficient water evaporates, white crystals of phosphorous acid will appear upon cooling. The crystals are deliquescent, very soluble in water, and have an odor like that of garlic. The solid melts at 70.1 °C and decomposes at about 200 °C by disproportionation into phosphine and orthophosphoric acid:
\[\ce{4 H_3PO_3(l) \longrightarrow PH_3(g) + 3 H_3 PO_4(l)} \nonumber \]
Phosphorous acid forms only two series of salts, which contain the dihydrogen phosphite ion, \(\ce{H2PO3^{-}}\), or the hydrogen phosphate ion, \(\ce{HPO3^{2-}}\) respectively. It is not possible to replace the third atom of hydrogen because it is not very acidic, as it is not easy to ionize the P-H bond.
Sulfur Oxyacids and Salts
The preparation of sulfuric acid, H 2 SO 4 (shown in Figure \(\PageIndex{13}\)), begins with the oxidation of sulfur to sulfur trioxide and then converting the trioxide to sulfuric acid. Pure sulfuric acid is a colorless, oily liquid that freezes at 10.5 °C. It fumes when heated because the acid decomposes to water and sulfur trioxide. The heating process causes the loss of more sulfur trioxide than water, until reaching a concentration of 98.33% acid. Acid of this concentration boils at 338 °C without further change in concentration (a constant boiling solution) and is commercially concentrated H 2 SO 4 . The amount of sulfuric acid used in industry exceeds that of any other manufactured compound.
The strong affinity of concentrated sulfuric acid for water makes it a good dehydrating agent. It is possible to dry gases and immiscible liquids that do not react with the acid by passing them through the acid.
Sulfuric acid is a strong diprotic acid that ionizes in two stages. In aqueous solution, the first stage is essentially complete. The secondary ionization is not nearly so complete, and \(\ce{HSO4^{-}}\) is a moderately strong acid (about 25% ionized in solution of a \(\ce{HSO4^{-}}\) salt (\(K_a = 1.2 \times 10^{−2}}\)).
Being a diprotic acid, sulfuric acid forms both sulfates, such as Na 2 SO 4 , and hydrogen sulfates, such as NaHSO 4 . Most sulfates are soluble in water; however, the sulfates of barium, strontium, calcium, and lead are only slightly soluble in water.
Among the important sulfates are Na 2 SO 4 ⋅10H 2 O and Epsom salts, MgSO 4 ⋅7H 2 O. Because the\(\ce{HSO4^{-}}\) ion is an acid, hydrogen sulfates, such as NaHSO 4 , exhibit acidic behavior, and this compound is the primary ingredient in some household cleansers.
Hot, concentrated sulfuric acid is an oxidizing agent. Depending on its concentration, the temperature, and the strength of the reducing agent, sulfuric acid oxidizes many compounds and, in the process, undergoes reduction to SO 2 , \(\ce{HSO3^{-}}\), \(\ce{SO3^{2-}}\), S, H 2 S , or S 2− .
Sulfur dioxide dissolves in water to form a solution of sulfurous acid, as expected for the oxide of a nonmetal. Sulfurous acid is unstable, and it is not possible to isolate anhydrous H 2 SO 3 . Heating a solution of sulfurous acid expels the sulfur dioxide. Like other diprotic acids, sulfurous acid ionizes in two steps: The hydrogen sulfite ion, \(\ce{HSO3^{-}}\) and the sulfite ion, \(\ce{SO3^{2-}}\), form. Sulfurous acid is a moderately strong acid. Ionization is about 25% in the first stage, but it is much less in the second (\(K_{a1} = 1.2 \times 10^{−2}\) and \(K_{a2} = 6.2 \times 10^{−8}\)).
In order to prepare solid sulfite and hydrogen sulfite salts, it is necessary to add a stoichiometric amount of a base to a sulfurous acid solution and then evaporate the water. These salts also form from the reaction of SO 2 with oxides and hydroxides. Heating solid sodium hydrogen sulfite forms sodium sulfite, sulfur dioxide, and water:
\[\ce{2 NaHSO_3(s) ->[\Delta] Na_2SO_3(s) + SO_2(g) + H2O(l)} \nonumber \]
Strong oxidizing agents can oxidize sulfurous acid. Oxygen in the air oxidizes it slowly to the more stable sulfuric acid:
\[\ce{2 H_2 SO_3(aq) + O_2(g) + 2 H2O(l) ->[\Delta] 2 H3O^{+}(aq) + 2 HSO_4^{-}(aq)} \nonumber \]
Solutions of sulfites are also very susceptible to air oxidation to produce sulfates. Thus, solutions of sulfites always contain sulfates after exposure to air.
Halogen Oxyacids and Their Salts
The compounds HXO, HXO 2 , HXO 3 , and HXO 4 , where X represents Cl, Br, or I, are the hypohalous, halous, halic, and perhalic acids, respectively. The strengths of these acids increase from the hypohalous acids, which are very weak acids, to the perhalic acids, which are very strong. Table \(\PageIndex{1}\) lists the known acids, and, where known, their pK a values are given in parentheses.
| Name | Fluorine | Chlorine | Bromine | Iodine |
|---|---|---|---|---|
| hypohalous | HOF | HOCl (7.5) | HOBr (8.7) | HOI (11) |
| halous | HClO 2 (2.0) | |||
| halic | HClO 3 | HBrO 3 | HIO 3 (0.8) | |
| perhalic | HClO 4 | HBrO 4 | HIO 4 (1.6) | |
| paraperhalic | H 5 IO 6 (1.6) |
The only known oxyacid of fluorine is the very unstable hypofluorous acid, HOF, which is prepared by the reaction of gaseous fluorine with ice:
\[\ce{F_2(g) + H2O(s) \longrightarrow HOF(g) + HF(g)} \nonumber \]
The compound is very unstable and decomposes above −40 °C. This compound does not ionize in water, and there are no known salts. It is uncertain whether the name hypofluorous acid is even appropriate for HOF; a more appropriate name might be hydrogen hypofluorite.
The reactions of chlorine and bromine with water are analogous to that of fluorine with ice, but these reactions do not go to completion, and mixtures of the halogen and the respective hypohalous and hydrohalic acids result. Other than HOF, the hypohalous acids only exist in solution. The hypohalous acids are all very weak acids; however, HOCl is a stronger acid than HOBr, which, in turn, is stronger than HOI.
The addition of base to solutions of the hypohalous acids produces solutions of salts containing the basic hypohalite ions, OX − . It is possible to isolate these salts as solids. All of the hypohalites are unstable with respect to disproportionation in solution, but the reaction is slow for hypochlorite. Hypobromite and hypoiodite disproportionate rapidly, even in the cold:
\[\ce{3 XO^{-}(aq) \longrightarrow 2 X^{-}(aq) + XO_3^{-}(aq)} \nonumber \]
Sodium hypochlorite is an inexpensive bleach (Clorox) and germicide. The commercial preparation involves the electrolysis of cold, dilute, aqueous sodium chloride solutions under conditions where the resulting chlorine and hydroxide ion can react. The net reaction is:
\[\ce{Cl^{-}(aq) + H2O(l) \stackrel{\text { electrical energy }}{\longrightarrow} ClO^{-}(aq) + H_2(g)} \nonumber \]
The only definitely known halous acid is chlorous acid, HClO 2 , obtained by the reaction of barium chlorite with dilute sulfuric acid:
\[\ce{Ba \left( ClO_2\right)_2(aq) + H_2 SO_4(aq) \longrightarrow BaSO_4(s) + 2 HClO_2(aq)} \nonumber \]
Filtering the insoluble barium sulfate leaves a solution of HClO 2 . Chlorous acid is not stable; it slowly decomposes in solution to yield chlorine dioxide, hydrochloric acid, and water. Chlorous acid reacts with bases to give salts containing the chlorite ion (shown in Figure \(\PageIndex{14}\)). Sodium chlorite finds an extensive application in the bleaching of paper because it is a strong oxidizing agent and does not damage the paper.
Chloric acid, HClO 3 , and bromic acid, HBrO 3 , are stable only in solution. The reaction of iodine with concentrated nitric acid produces stable white iodic acid, HIO 3 :
\[\ce{I_2(s) + 10 HNO_3(aq) \longrightarrow 2 HIO_3(s) + 10 NO_2(g) + 4 H2O(l)} \nonumber \]
It is possible to obtain the lighter halic acids from their barium salts by reaction with dilute sulfuric acid. The reaction is analogous to that used to prepare chlorous acid. All of the halic acids are strong acids and very active oxidizing agents. The acids react with bases to form salts containing chlorate ions (shown in Figure \(\PageIndex{15}\)). Another preparative method is the electrochemical oxidation of a hot solution of a metal halide to form the appropriate metal chlorates. Sodium chlorate is a weed killer; potassium chlorate is used as an oxidizing agent.
Perchloric acid, HClO 4 , forms when treating a perchlorate, such as potassium perchlorate, with sulfuric acid under reduced pressure. The HClO 4 can be distilled from the mixture:
\[\ce{KClO_4(s) + H_2 SO_4(aq) \longrightarrow HClO_4(g) + KHSO_4(s)} \nonumber \]
Dilute aqueous solutions of perchloric acid are quite stable thermally, but concentrations above 60% are unstable and dangerous. Perchloric acid and its salts are powerful oxidizing agents, as the very electronegative chlorine is more stable in a lower oxidation state than 7+. Serious explosions have occurred when heating concentrated solutions with easily oxidized substances. However, its reactions as an oxidizing agent are slow when perchloric acid is cold and dilute. The acid is among the strongest of all acids. Most salts containing the perchlorate ion (shown in Figure \(\PageIndex{16}\)) are soluble. It is possible to prepare them from reactions of bases with perchloric acid and, commercially, by the electrolysis of hot solutions of their chlorides.
Perbromate salts are difficult to prepare, and the best syntheses currently involve the oxidation of bromates in basic solution with fluorine gas followed by acidification. There are few, if any, commercial uses of this acid or its salts.
There are several different acids containing iodine in the 7+-oxidation state; they include metaperiodic acid, HIO 4 , and paraperiodic acid, H 5 IO 6 . These acids are strong oxidizing agents and react with bases to form the appropriate salts.


35: The Nervous System
A nervous system is an organism’s control center: it processes sensory information from outside (and inside) the body and controls all behaviors—from eating to sleeping to finding a mate.
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- 35.0: Prelude to the Nervous System
- When you’re reading this book, your nervous system is performing several functions simultaneously. The visual system is processing what is seen on the page; the motor system controls the turn of the pages (or click of the mouse); the prefrontal cortex maintains attention. Even fundamental functions, like breathing and regulation of body temperature, are controlled by the nervous system.
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- 35.1: Neurons and Glial Cells
- Nervous systems throughout the animal kingdom vary in structure and complexity. Some organisms, like sea sponges, lack a true nervous system. Others, like jellyfish, lack a true brain and instead have a system of separate but connected nerve cells (neurons) called a “nerve net.” Echinoderms such as sea stars have nerve cells that are bundled into fibers called nerves.
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- 35.2: How Neurons Communicate
- All functions performed by the nervous system—from a simple motor reflex to more advanced functions like making a memory or a decision—require neurons to communicate with one another. While humans use words and body language to communicate, neurons use electrical and chemical signals. Just like a person in a committee, one neuron usually receives and synthesizes messages from multiple other neurons before “making the decision” to send the message on to other neurons.
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- 35.3: The Central Nervous System
- The central nervous system is made up of the brain and spinal cord and is covered with three layers of protective coverings called meninges (from the Greek word for membrane). The outermost layer is the dura mater with the primary function for this thick layer is to protect the brain and spinal cord. The dura mater also contains vein-like structures that carry blood from the brain back to the heart. The middle layer is the web-like arachnoid mater. The last layer is the pia mater.
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- 35.4: The Peripheral Nervous System
- The peripheral nervous system (PNS) is the connection between the central nervous system and the rest of the body. The central nervious system (CNS) is like the power plant of the nervous system. It creates the signals that control the functions of the body. The PNS is like the wires that go to individual houses. Without those “wires,” the signals produced by the CNS could not control the body (and the CNS would not be able to receive sensory information from the body either).
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- 35.5: Nervous System Disorders
- A nervous system that functions correctly is a fantastically complex, well-oiled machine—synapses fire appropriately, muscles move when needed, memories are formed and stored, and emotions are well regulated. Unfortunately, each year millions of people in the United States deal with some sort of nervous system disorder.
 (Photo by Robina Weermeijer on Unsplash )


4.13: Directional Terms 2 (Worksheet)
Name: ______________________________
Section: _____________________________
Student ID#:__________________________
Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.
Insert the missing directional terms:
- 1. The spleen is.................to the kidneys
- 2. The hock is...................to the stifle.
- 3. The adrenal gland is...................to the kidney.
- 4. The thymus is......................to the heart.
- 5. The thyroid is....................to the trachea.
- 6. The stomach is...................to the heart.
- 7. The withers region is..................to the sternum.
- 8. The stifle is .....................to the fetlock
- 9. The lumbar vertebrae are.....................to the sacrum
- 10. The sacrum is......................to the pelvic girdle
- 11. The fibula is.......................to the tibia
- 12. The metacarpals are...................to the carpals
- 13. The pericardium is...................to the heart
- 14. The diaphragm is......................to the lungs
- 15. The hair follicle is...................to the hair shaft
- 16. The eyeball is.........................to the orbit
- 17. The mandible is.........................to the tongue
- 18. The tibia is.........................to the femur
- 19. The radius is........................to the metacarpals


11.3: Introduction to Multiple Sclerosis
By the end of this section, you should be able to:
- 11.3.1 Describe the pathophysiology of multiple sclerosis.
- 11.3.2 Identify the clinical manifestations related to multiple sclerosis.
- 11.3.3 Identify the etiology and diagnostic studies related to multiple sclerosis.
Multiple sclerosis (MS) is a debilitating, inflammatory, immune-mediated condition. According to the National Multiple Sclerosis Society (2023), studies have confirmed that nearly 1 million people are living with MS in the United States. This disease is characterized by a progressive and irreversible demyelination and axonal degeneration of the brain, spinal cord, and optic nerves. Myelin is a protective sheath that acts as an insulator of the electrical signal (see Figure 11.4). It allows rapid conduction of a nerve impulse down the axon. Degeneration of the myelin sheath results in the inability of nerves to conduct electrical impulses. As the myelin deteriorates, oligodendrocytes repair the damage but also form scar tissue called gliotic plaques. These plaques will begin to interfere with electrical impulses traveling through the axon. Over time, the myelin cannot regenerate and nerves eventually wither away. Typically, the client experiences remission s and exacerbations throughout the progression. Sensory and motor deficits become worse as the client ages. The disease is progressive and affects nerves in both the CNS and peripheral nervous system (PNS) (Capriotti, 2020).
Pharmacologic Management
There is currently no cure for MS; however, the use of drugs has made a significant difference in the lives of those with MS. Most of the drugs target specific symptoms, reduce relapse rates, and delay progression. In the most common form (relapsing-remitting), early initiation of medications is highly recommended. Several drug classifications are used that work through different mechanisms: corticosteroids can reduce inflammation and speed recovery during acute exacerbations; beta interferons can slow damage; and disease-modifying agents and immunomodulators suppress the immune system to prevent the antibodies from attacking their own cells. Additionally, various components of the immune system are specifically targeted by medications. Some drugs reduce the number of T cells circulating in the periphery; others destroy target B cells or deplete B and T cells; still others prevent leukocyte mobilization to injured tissue. Drugs, such as antispasmodics, antidepressants, and antiepileptics, are prescribed to control symptoms.
Nonpharmacologic Management
Plasmapheresis (removal of abnormal antibodies) can be done for those who do not respond well to drugs. Significant nonpharmacologic management should involve teaching the client coping mechanisms, ensuring support systems are in place, and emphasizing proper nutrition and sufficient rest; the client should be encouraged to incorporate exercise into their daily routine. These actions can promote overall health, which can help the client better deal with symptoms of relapse as well as maintain their quality of life. Finally, physical therapy and occupational therapy can help to maximize functioning in various ways (National Institute of Neurological Disorders and Stroke, 2023a).
Trending Today
Advances in Multiple Sclerosis Treatment
According to the National Institute of Neurological Disorders and Stroke (2023a), researchers continue to study the mechanism of MS to identify ways to prevent or stop the continuous decline in function seen in clients with this progressive disease. Ublituximab (Briumvi) recently became the third anti-CD20 monoclonal antibody approved by the FDA as a treatment for relapsing forms of MS (Cunha, 2023). This drug is administered over 1 hour and given twice a year.
Clinical Tip
Treating an Acute Relapse
A short course of a high-dose intravenous (IV) glucocorticoid (e.g., 500–1000 mg of methylprednisolone daily for 3–5 days) is the preferred treatment for an acute episode. These drugs suppress inflammation and can reduce the severity and duration of an attack. When used short-term, these drugs are safe except for a possible elevation of blood glucose levels. In contrast, long-term use (e.g., over 3 weeks) can cause multiple adverse effects in numerous areas of the body, including adrenal insufficiency leading to fluid and electrolyte imbalances, osteoporosis, high risk for infections, myopathy, and psychological disturbances (agitation, anxiety, or irritability).
Acute relapse may also be treated with IV gamma globulin. This option is especially beneficial for clients who are unable to tolerant or respond adequately to glucocorticoids.


8.2.3: Multi-step Experiments
Lesson
Let's look at probabilities of experiments that have multiple steps.
Exercise \(\PageIndex{1}\): True or False?
Is each equation true or false? Explain your reasoning.
\(8=(8+8+8+8)\div 3\)
\((10+10+10+10+10)\div 5=10\)
\(6+4+6+4+6+4)\div 6=5\)
Exercise \(\PageIndex{2}\): Spinning a Color and Number
The other day, you wrote the sample space for spinning each of these spinners once.
What is the probability of getting:
- Green and 3?
- Blue and any odd number?
- Any color other than red and any number other than 2?
Exercise \(\PageIndex{3}\): Cubes and Coins
The other day you looked at a list, a table, and a tree that showed the sample space for rolling a number cube and flipping a coin.
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Your teacher will assign you one of these three structures to use to answer these questions. Be prepared to explain your reasoning.
- What is the probability of getting tails and a 6?
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What is the probability of getting heads and an odd number?
Pause here so your teacher can review your work.
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Suppose you roll two number cubes. What is the probability of getting:
- Both cubes showing the same number?
- Exactly one cube showing an even number?
- At least one cube showing an even number?
- Two values that have a sum of 8?
- Two values that have a sum of 13?
- Jada flips three quarters. What is the probability that all three will land showing the same side?
Exercise \(\PageIndex{4}\): Pick a Card
Imagine there are 5 cards. They are colored red, yellow, green, white, and black. You mix up the cards and select one of them without looking. Then, without putting that card back, you mix up the remaining cards and select another one.
- Write the sample space and tell how many possible outcomes there are.
- What structure did you use to write all of the outcomes (list, table, tree, something else)? Explain why you chose that structure.
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What is the probability that:
- You get a white card and a red card (in either order)?

- You get a blue card?
- You get 2 cards of the same color?
- You get 2 cards of different colors?
Are you ready for more?
In a game using five cards numbered 1, 2, 3, 4, and 5, you take two cards and add the values together. If the sum is 8, you win. Would you rather pick a card and put it back before picking the second card, or keep the card in your hand while you pick the second card? Explain your reasoning.
Summary
Suppose we have two bags. One contains 1 star block and 4 moon blocks. The other contains 3 star blocks and 1 moon block.
If we select one block at random from each, what is the probability that we will get two star blocks or two moon blocks?
To answer this question, we can draw a tree diagram to see all of the possible outcomes.
There are \(5\cdot 4=20\) possible outcomes. Of these, 3 of them are both stars, and 4 are both moons. So the probability of getting 2 star blocks or 2 moon blocks is \(\frac{7}{20}\).
In general, if all outcomes in an experiment are equally likely, then the probability of an event is the fraction of outcomes in the sample space for which the event occurs.
Practice
Exercise \(\PageIndex{5}\)
A vending machine has 5 colors (white, red, green, blue, and yellow) of gumballs and an equal chance of dispensing each. A second machine has 4 different animal-shaped rubber bands (lion, elephant, horse, and alligator) and an equal chance of dispensing each. If you buy one item from each machine, what is the probability of getting a yellow gumball and a lion band?
Exercise \(\PageIndex{6}\)
The numbers 1 through 10 are put in one bag. The numbers 5 through 14 are put in another bag. When you pick one number from each bag, what is the probability you get the same number?
Exercise \(\PageIndex{7}\)
When rolling 3 standard number cubes, the probability of getting all three numbers to match is \(\frac{6}{216}\). What is the probability that the three numbers do not all match? Explain your reasoning.
Exercise \(\PageIndex{8}\)
For each event, write the sample space and tell how many outcomes there are.
- Roll a standard number cube. Then flip a quarter.
- Select a month. Then select 2020 or 2025.
(From Unit 8.2.2)
Exercise \(\PageIndex{9}\)
On a graph of the area of a square vs. its perimeter, a few points are plotted.
- Add some more ordered pairs to the graph.
- Is there a proportional relationship between the area and perimeter of a square? Explain how you know.
(From Unit 2.4.2)


11: Facilitation of Elimination Last updated Save as PDF Page ID 77036 Ernstmeyer & Christman (Eds.) Chippewa Valley Technical College via OpenRN 11.1: Facilitation of Elimination Introduction 11.2: Basic Concepts 11.3: Preventing CAUTI 11.4: Inserting and Managing Indwelling Urinary Catheters 11.5: Obtaining Urine Specimen for Culture 11.6: Removing an Indwelling Urinary Catheter 11.7: Managing Ostomies 11.8: Applying the Nursing Process to Catheterization 11.9: Sample Documentation 11.10: Checklist for Foley Catheter Insertion (Male) 11.11: Checklist for Foley Catheter Insertion (Female) 11.12: Checklist for Obtaining a Urine Specimen from a Foley Catheter 11.13: Checklist for Foley Removal 11.14: Checklist for Straight Catheterization – Female/Male 11.15: Checklist for Ostomy Appliance Change 11.16: Learning Activities 11.17: XXI Glossary Thumbnail: Urinary catheter. (Public Domain; Saltanat ebli via Wikimedia Commons )


15.5: Conclusion
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The aim of this study has been to demonstrate the importance of accounting for writing as material and as part of individual and social practice. The ‘feature group’ approach has an important contribution to make to the study of the materiality of writing of 18 th –20 th century Britain. Whilst each feature contains its own narrative, the aim of analysis at the scale of the ‘feature group’ was not solely to consider the individual assemblage in isolation but as a starting point for discovering larger patterns. The ‘elephant in the room’ is the fact that what survives archaeologically is only a subset of past writing materialities. The most common medium for writing in 18 th –20 th century Britain, probably by several orders of magnitude, was undoubtedly paper. This did not survive in any of the feature groups discussed, but in those rare archaeological instances where paper does survive from this period it vastly outnumbers writing on other materials (e.g. Crook and Murray 2006). Archaeologically, this scenario where the dominant medium for writing is the least likely to survive is paralleled in other cultures (e.g. Waal 2011). It is clear that in 18 th –20 th century Britain writing on paper was regarded as the norm, with all other materials viewed as secondary. Indeed many of the examples discussed are derived either directly or indirectly from writing on paper. Examples of this include the cup with text from a published poem ( Figure 6 ), the Sicilian pattern vessels which rely upon a novel for much of their meaning ( Figure 7 ), the Trajan pattern jug whose imagery relates to the Panegyricus Trajani ( Figure 9 ) and children’s mugs which derive from and in one case actually depict the bible ( Figure 10 ), the book par excellence of Britain during this period. In other cases the writing makes no sense without the existence of writing on paper; for example registration marks are meaningless without both the enabling Act of Parliament and the supporting ‘paper trail’ of the individual registration process ( Figures 9–11 ). The archaeological preponderance of writing on what might be viewed as secondary expression raises significant questions about what studying its materiality can tell us.
The use of writing, both on paper and other materials, becomes increasing prevalent over the period in question. As a counterpoint to this phenomenon the texts and their meanings on materials other than paper in many cases becomes less visible — apparently not meant to be read by those who are otherwise consumers of the objects. Furthermore, much of the writing relates to regulation and there are also repeated links to the education of children and both commercial and institutional branding. All of these phenomena, as well as the crucial underpinning factor of increasing literacy rates at this time, must therefore be situated in the context of major historical processes of the period such as modernity, capitalism and consumerism. The archaeological study of writing as material practice at the scale of feature groups sheds light on how particular households in specific temporal, spatial and social milieux interacted with those forms of writing that survive. At a broader level these specific examples attest to the development and spread of a text-saturated culture, a phenomenon which is inextricably intertwined with the major historical processes affecting 18 th –20 th century Britain.