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Grade Level


Acids and Bases Unit

Properties of Acids and Bases Lab
Stephanie Dickerson
11 Grade Chemistry
The prior knowledge required for this lesson is an understanding of how to
identify an acid (H as the cation) and a base (OH as the anion). The students
will also need to have an understanding of strong, weak and non-electrolytes.
They will need to know how to identify the characteristics of each when
performing a conductivity test. The students will need to know what happens
to a compound in solution for it to be a strong, weak or non-electrolyte. This
prior knowledge was taught in the lesson that precedes this one using guided
notes and several practice problems. Electrolytes were taught during the
solutions unit and were assessed during a lab and a summative assessment of
the entire unit. Now that the students have been given the vocabulary and
background knowledge needed to further examine acids and bases, this lab
will be used to allow the students a hands on experience with using several
different techniques to determine if a substance is acidic or basic. The
students will use their knowledge from the previous day to identify changes
that occur to litmus paper, pH paper and indicators when a substance is acidic
or basic.

Standards Met
SC.CHE.2.1.e- Acids and Bases
SC.9-12.SIA.1- identify questions and concepts that guide scientific
SC.9-12.SIA.2- design and conduct scientific investigations
SC.9-12.SIA.3- use technology and mathematics to improve investigations
and communications
SC.9-12.SIA.5- recognize and analyze explanations and models
SC.9-12.SIA.6- communicate and defend a scientific argument

Properties of acids and bases and the ranges of the pH scale were introduced
in middle school. In chemistry, the structural features of molecules are
explored to further understand acids and bases. Acids often result when
hydrogen is covalently bonded to an electronegative element and is easily
dissociated from the rest of the molecule to bind with water to form a
hydronium ion (H3O+). The acidity of an aqueous solution can be expressed
as pH, where pH can be calculated from the concentration of the hydronium
ion. Bases are likely to dissociate in water to form a hydroxide ion. Acids can
react with bases to form a salt and water. Such neutralization reactions can be
studied quantitatively by performing titration experiments. Detailed
instruction about the equilibrium of acids and bases and the concept of

Acids and Bases Unit

Properties of Acids and Bases Lab
Stephanie Dickerson
Brnsted-Lowry and Lewis acids and bases will not be assessed at this level.

The big idea of this lesson is to have students further develop their
understanding of acids and bases by making observations of changes that
occur when using indicators and other methods such as litmus paper and pH
paper. The students will be able to see what happens when a base or acid
becomes stronger or weaker. The physical color changes that can be seen by
using these methods allow for students to connect the knowledge they gained
yesterday with something they can actually see. This lesson is related to the
central focus because it is furthering the students background knowledge of
acids and bases and the characteristics they exhibit. This activity is also
giving students experience with the pH scale before they to mathematically
calculate this value.


The students will be able to:



Differentiate between a weak electrolyte and a strong electrolyte

Describe properties of acids and bases (conductivity, strength)
Determine if a substance is acidic or basic based on the pH
Determine the pH of a substance using pH paper
Determine if a substance is basic by using red litmus paper
Determine if a substance is acidic by using blue litmus paper
Determine if a substance is basic using the indicator phenolphthalein
Determine if a substance is acidic or basic using a universal indicator.
Make observations of the changes that occur when using litmus
paper, pH paper and indicators
The essential vocabulary chosen for this lesson is:
Indicator- any substance that gives a visible sign, usually by a color
change, of the presence or absence of a threshold concentration of a
chemical species, such as an acid or a base in a solution
Strong Acid- an acid that completely dissociates in a solution
(provided there is sufficient solvent) releasing hydrogen ions
Weak Acid- an acid that dissociates incompletely, releasing only
some of its hydrogen atoms into the solution
Strong Base- a base that completely dissociates in a solution
releasing hydroxide ions
Weak Base- a base that dissociates incompletely, releasing only some
of it hydroxide ions.
Strong Electrolyte- a solute that completely dissociates in solution
and conduct electricity very well.
Weak Electrolyte- a solute that partially dissociates in a solution and
slightly conducts electricity
Non-electrolyte- a solute that produces no ions in a solution and
cannot conduct electricity.
Direct Instruction- this will be used as I give the students a
walkthrough of the instructions for the lab as to not overwhelm them
with the amount of materials they will be using and the number of


Safety Needs
and Instruction

Acids and Bases Unit

Properties of Acids and Bases Lab
Stephanie Dickerson
tests they will be running on their five substances.
Cooperative learning- the students will be working in groups of three
or four while they are completing the experiments and they will work
on their post lab questions as a group also.
Small Group Instruction- as the students break off into their groups to
complete the activity, time will be spent at each table asking the
students what they are observing with each of the substances and
what they think that means about the properties of the substance.
Active Learning- the students are completing an experiment that
allows them to interact with strong and weak acids and bases so they
are able to physically see the properties demonstrated by each
component. Through this lab the students can connect the vocabulary
they received the previous day to an activity they actually completed.
1. 25 copies of Properties of Acids and Bases Lab
2. Safety goggles (class set)
3. Materials for Lab
Distilled Water
Acetic Acid (HC2H3O2)
Hydrochloric Acid (HCl)
Ammonia (NH3)
Sodium Hydroxide (NaOH)
Conductivity Meter
Red Litmus Paper
Blue Litmus Paper
pH Paper
Universal Indicator
Mg Ribbon
Well Plate
4. Materials for Conductivity Test
5 200 mL beakers
Light bulb probe
Students will need to wear safety goggles for the duration of the lab and will
need to complete the portion of the lab using the magnesium ribbon one at a
time inside the fume hood incase an excess of fumes are produced.
Pre-class Prep: All materials will be pulled from the chemical storeroom
ahead of time and 6 bins will be constructed with all the materials the
students will need. In each bin there will be:
Wash bottle of distilled water
Drop bottle of acetic acid
Drop bottle of HCl
Drop bottle of ammonia
Drop bottle of sodium hydroxide
Drop bottle of universal indicator
Drop bottle of phenolphthalein
Tube of red litmus paper


Acids and Bases Unit

Properties of Acids and Bases Lab
Stephanie Dickerson
Tube of blue litmus paper
Roll of pH paper with a color scale
Well plate
1 Procedure placed in a plastic sleeve

Gather 5 200 mL beakers and place each substance in its own beaker. Plug
the light bulb probe into the wall to use during the conductivity test.
Engagement/Introduction/Hook (5 minutes): The bellwork will consist of
a small set of guided notes that lays out the parameters of the pH scale. 0-6
acidic, 7 neutral, 8-14 basic. The notes will also explain the use of indicators
in acid base chemistry. Explain to students the lab today will be examining
properties of acids and bases.
Transition 1 (5 minutes): Have students gather around the counter where the
5 beakers have been set up with the light bulb probe.
Segment 1 (10 minutes): Take the light bulb probe and place it inside the
beakers containing each substance. Have the students record their
observations of if the substance has strong, weak or no conductivity in the
first row of their data tables.
Transition 2 (5 minutes): Have students retrieve goggles and a bin with all
their materials for the group. Instruct the students to raise their hands when
they are ready for the Mg ribbon.
Segment 2 (30 minutes): The students will spend this time conducting their
experiments with each substance using their well plates and the other
materials provided in the bin. The students will come and ask for the Mg
ribbon when they are ready for this set of tests. I will supervise the fume
hood as they complete this experiment.
Closure (3 minutes): Remind students that the Acid Base POGIL homework
is due tomorrow and that we will work on the post lab questions tomorrow in

Assessments of

The conductivity test was done as a class so that the students would not have
to deduce on their own the what the meaning of the strengths of the lights
were. This was also used as a review for the entire class on some of the
concepts learned from the solutions unit. Some of the students showed
difficulty with mastering the concepts of electrolytes so I used this
opportunity to present the topic again in a visual manner. There was also an
extensive verbal walkthrough of the procedures given to the students before
the lab started. Key instructional points were highlighted to maximize student
success and minimize student error throughout the course of the lab.
Formative assessments: Explanation Analysis (taken from Page Keeleys
book SCIENCE Formative Assessment)- this will be used as the students are
answering the post lab questions. The students will work in their groups to
explain the observations they made and what they mean in regards to acids
and bases. They will be expected to have conversations amongst themselves
while explaining and challenging each others explanations. I will pause at
each group to listen in on the students discussions and to give my input in

Acids and Bases Unit

Properties of Acids and Bases Lab
Stephanie Dickerson
the form of questions as needed.
Summative assessments: The post lab questions will be graded for accuracy.

Acids and Bases Unit

Properties of Acids and Bases Lab
Stephanie Dickerson

Acids and Bases Unit

Properties of Acids and Bases Lab
Stephanie Dickerson