21.2: Speciation
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One of the best definition os species is that of the evolutionary biologist Ernst Mayr: "A species is an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so." However, sometimes breeding may take place (as it can between a horse and a donkey) but if so, the offspring are not so fertile and/or well adapted as the parents (the mule produced is sterile).
Allopatric Speciation: the Role of Isolation in Speciation
The formation of two or more species often (some workers think always!) requires geographical isolation of subpopulations of the species. Only then can natural selection or perhaps genetic drift produce distinctive gene pools. It is no accident that the various races (or " subspecies ") of animals almost never occupy the same territory. Their distribution is allopatric ("other country").
The seven distinct subspecies or races of the yellowthroat Geothlypis trichas (a warbler) in the continental U.S. would soon merge into a single homogeneous population if they occupied the same territory and bred with one another.
Darwin's Finches
As a young man of 26, Charles Darwin visited the Galapagos Islands off the coast of Ecuador. Among the animals he studied were what appeared to be 13 species * of finches found nowhere else on earth.
- Some have stout beaks for eating seeds of one size or another (#2, #3, #6).
- Others have beaks adapted for eating insects or nectar.
- One (#7) has a beak like a woodpecker's. It uses it to drill holes in wood, but lacking the long tongue of a true woodpecker, it uses a cactus spine held in its beak to dig the insect out.
- One (#12) looks more like a warbler than a finch, but its eggs, nest, and courtship behavior is like that of the other finches.
Darwin's finches. The finches numbered 1–7 are ground finches. They seek their food on the ground or in low shrubs. Those numbered 8–13 are tree finches. They live primarily on insects.
1. Large cactus finch (
Geospiza conirostris
)
2. Large ground finch (
Geospiza magnirostris
)
3. Medium ground finch (
Geospiza fortis
)
4. Cactus finch (
Geospiza scandens
)
5. Sharp-beaked ground finch (
Geospiza difficilis
)
6. Small ground finch (
Geospiza fuliginosa
)
7. Woodpecker finch (
Cactospiza pallida
)
8. Vegetarian tree finch (
Platyspiza crassirostris
)
9. Medium tree finch (
Camarhynchus pauper
)
10. Large tree finch (
Camarhynchus psittacula
)
11. Small tree finch (
Camarhynchus parvulus
)
12. Warbler finch (
Certhidia olivacea
)
13. Mangrove finch (
Cactospiza heliobates
)
(From BSCS, Biological Science: Molecules to Man, Houghton Mifflin Co., 1963)
* Genetic analysis provides evidence that:
- There are actually two species of warbler finch — Certhidia olivacea now called the green warbler finch and Certhidia fusca , the gray warbler finch.
- The various populations of Geospiza difficilis found on the different islands belong to one or another of three clades so genetically distinct that they deserve full species status.
Whether the number is 13 or 17, since Darwin's time, these birds have provided a case study of how a single species reaching the Galapagos from Central or South America could - over a few million years - give rise to the various species that live there today. Several factors have been identified that may contribute to speciation.
Ecological opportunity
When the ancestor of Darwin's finches reached the Galapagos, it found no predators (There were no mammals and few reptiles on the islands.) and few, if any, competitors . There were only a handful of other types of songbirds. In fact, if true warblers or woodpeckers had been present, their efficiency at exploiting their niches would surely have prevented the evolution of warblerlike and woodpeckerlike finches.
Geographical Isolation (allopatry)
The proximity of the various islands has permitted enough migration of Darwin's finches between them to enable distinct island populations to arise. But the distances between the islands is great enough to limit interbreeding between populations on different islands. This has made possible the formation of distinctive subspecies ( = races ) on the various islands.
The importance of geographical isolation is illuminated by a single, fourteenth, species of Darwin's finches that lives on Cocos Island , some 500 miles (800 km) to the northeast of the Galapagos. The first immigrants there must also have found relaxed selection pressures with few predators or competitors. How different the outcome, though. Where one immigrant species gave rise to at least 13 on the scattered Galapagos Islands, no such divergence has occurred on the single, isolated Cocos Island.
Evolutionary Change
In isolation, changes in the gene pool can occur through some combination of natural selection, genetic drift, and founder effect. These factors may produce distinct subpopulations on the different islands. So long as they remain separate ( allopatric ) we consider them races or subspecies . In fact, they might not be able to interbreed with other races but so long as we don't know, we assume that they could.
How much genetic change is needed to create a new species? Perhaps not as much as you might think. For example, changes at one or just a few gene loci might do the trick. For example, a single mutation altering flower color or petal shape could immediately prevent cross-pollination between the new and the parental types (a form of prezygotic isolating mechanism).
Reunion
The question of their status - subspecies or true species - is resolved if they ever do come to occupy the same territory again (become sympatric ). If successful interbreeding occurs, the differences will gradually disappear, and a single population will be formed again. Speciation will not have occurred. If, on the other hand, two subspecies reunite but fail to resume breeding, speciation has occurred and they have become separate species.
An example: The medium tree finch Camarhynchus pauper is found only on Floreana Island . Its close relative, the large tree finch, Camarhynchus psittacula , is found on all the central islands including Floreana. Were it not for its presence on Floreana, both forms would be considered subspecies of the same species. Because they do coexist and maintain their separate identity on Floreana, we know that speciation has occurred.
Isolating Mechanisms
What might keep two subpopulations from interbreeding when reunited geographically? There are several mechanisms.
Prezygotic Isolating Mechanisms act before fertilization occurs. Sexual selection - a failure to elicit mating behavior. On Floreana, Camarhynchus psittacula has a longer beak than Camarhynchus pauper , and the research teams led by Peter and Rosemary Grant have demonstrated that beak size is an important criterion by which Darwin's finches choose their mates. Two subpopulations may occupy different habitats in the same area and thus fail to meet at breeding time. In plants, a shift in the time of flowering can prevent pollination between the two subpopulations.  The sperm may fail to reach or fuse with the egg.
Postzygotic Isolating Mechanisms act even if fertilization does occur. Even if a zygote is formed, genetic differences may have become so great that the resulting hybrids are less viable or less fertile than the parental types. The sterile mule produced by mating a horse with a donkey is an example. Sterility in the males produced by hybridization is more common than in females.  When Drosophila melanogaster attempts to mate with its relative Drosophila simulans , no viable males are even produced. Mutations in a single gene (encoding a component of the nuclear pore complex) are responsible.
Reinforcement
When two species that have separated in allopatry become reunited, their prezygotic and postzygotic isolating mechanisms may become more stringent than those between the same species existing apart from each other. This phenomenon is called reinforcement . It arises from natural selection working to favor individuals that avoid interspecific matings, which would produce less-fit hybrids, when the two species are first reunited.
Speciation by Hybridization
Hybridization between related angiosperms is sometimes followed by a doubling of the chromosome number. The resulting polyploids are now fully fertile with each other although unable to breed with either parental type - a new species has been created. This appears to have been a frequent mechanism of speciation in angiosperms. Even without forming a polyploid, interspecific hybridization can occasionally lead to a new species of angiosperm. Two species of sunflower, the "common sunflower", Helianthus annuus , and the "prairie sunflower", H. petiolaris , grow widely over the western half of the United States. They can interbreed, but only rarely are fertile offspring produced.
However, Rieseberg and colleagues have found evidence that successful hybridization between them has happened naturally in the past. They have shown that three other species of sunflower (each growing in a habitat too harsh for either parental type) are each the product of an ancient hybridization between Helianthus annuus and H. petiolaris . Although each of these species has the same diploid number of chromosomes as the parents (2 n = 34), they each have a pattern of chromosome segments that have been derived, by genetic recombination , from both the parental genomes. They demonstrated this in several ways, notably by combining RFLP analysis with the polymerase chain reaction (PCR).
They even went on to produce (at a low frequency) annuus x petiolaris hybrids in the greenhouse that mimicked the phenotypes and genotypes of the natural hybrids. (These monumental studies were described in the 29 August 2003 issue of Science .)
Another example. In Pennsylvania, hybrids between a species of fruit fly (not Drosophila) that feeds on blueberries and another species (again, not Drosophila) that feeds on snowberries feed on honeysuckle where they neither encounter competition from their parental species nor have an opportunity to breed with them (no introgression). This study was published in the 28 July 2005 issue of Nature . So speciation can occur as a result of hybridization between two related species, if the hybrid
- receives a genome that enables it to breed with other such hybrids but not breed with either parental species,
- can escape to a habitat where it does not have to compete with either parent,
- is adapted to live under those new conditions.
Adaptive Radiation
The processes described in this page can occur over and over. In the case of Darwin's finches, they must have been repeated a number of times forming new species that gradually divided the available habitats between them. From the first arrival have come a variety of ground-feeding and tree-feeding finches as well as the warblerlike finch and the tool-using woodpeckerlike finch. The formation of a number of diverse species from a single ancestral one is called an adaptive radiation .
Speciateion in theHouse mice on the island of Madeira
A report in the 13 January 2000 issue of Nature describes a study of house mouse populations on the island of Madeira off the Northwest coast of Africa. These workers (Janice Britton-Davidian et al) examined the karyotypes of 143 house mice ( Mus musculus domesticus ) from various locations along the coast of this mountainous island.
Their findings:
- There are 6 distinct populations (shown by different colors)
- Each of these has a distinct karyotype, with a diploid number less than the "normal" (2 n = 40).
- The reduction in chromosome number has occurred through Robertsonian fusions . Mouse chromosomes tend to be acrocentric ; that is, the centromere connects one long and one very short arm. Acrocentric chromosomes are at risk of translocations that fuse the long arms of two different chromosomes with the loss of the short arms.
- The different populations are allopatric ; isolated in different valleys leading down to the sea.
- The distinct and uniform karyotype found in each population probably arose from genetic drift rather than natural selection.
- The 6 different populations are technically described as races because there is no opportunity for them to attempt interbreeding.
- However, they surely meet the definition of true species. While hybrids would form easily (no prezygotic isolating mechanisms), these would probably be infertile as proper synapsis and segregation of such different chromosomes would be difficult when the hybrids attempted to form gametes by meiosis.
Sympatric Speciation
Sympatric speciation refers to the formation of two or more descendant species from a single ancestral species all occupying the same geographic location. Some evolutionary biologists don't believe that it ever occurs. They feel that interbreeding would soon eliminate any genetic differences that might appear. But there is some compelling (albeit indirect) evidence that sympatric speciation can occur.
Speciation in three-spined sticklebacks
The three-spined sticklebacks, freshwater fishes that have been studied by Dolph Schluter (who received his Ph.D. for his work on Darwin's finches with Peter Grant) and his current colleagues in British Columbia, provide an intriguing example that is best explained by sympatric speciation.
They have found:
-
Two different species of three-spined sticklebacks in each of five different lakes.
- a large benthic species with a large mouth that feeds on large prey in the littoral zone
- a smaller limnetic species with a smaller mouth that feeds on the small plankton in open water.
- DNA analysis indicates that each lake was colonized independently, presumably by a marine ancestor, after the last ice age.
- DNA analysis also shows that the two species in each lake are more closely related to each other than they are to any of the species in the other lakes.
- Nevertheless, the two species in each lake are reproductively isolated; neither mates with the other.
-
However, aquarium tests showed that
- The benthic species from one lake will spawn with the benthic species from the other lakes and likewise the limnetic species from the different lakes will spawn with each other.
- These benthic and limnetic species even display their mating preferences when presented with sticklebacks from Japanese lakes; that is, a Canadian benthic prefers a Japanese benthic over its close limnetic cousin from its own lake.
-
Their conclusion: in each lake, what began as a single population faced such competition for limited resources that
- disruptive selection — competition favoring fishes at either extreme of body size and mouth size over those nearer the mean — coupled with
- assortative mating — each size preferred mates like it
- The fact that this pattern of speciation occurred the same way on three separate occasions suggests strongly that ecological factors in a sympatric population can cause speciation.
Sympatric speciation driven by ecological factors may also account for the extraordinary diversity of crustaceans living in the depths of Siberia's Lake Baikal.
How many genes are needed to start down the path to sympatric speciation?
Perhaps not very many. The European corn borer, Ostrinia nubilalis , (which despite its common name is a major pest in the U.S. as well) exists as two distinct races designated Z and E . Both can be found in the same area; that is, they are sympatric. But in the field, they practice assortative mating - only breeding with mates of their own race.
The females of both races synthesize and release a pheromone that is a sex attractant for the males. Both races use the same substance but different isomers of it. Which isomer is produced is under the control of a single enzyme-encoding gene locus. The ability of the males to respond to one isomer or the other is controlled by 2 loci.
The Problem of Clines
There is another possible way for new species to arise in the absence of geographical barriers. If a population ranges over a large area and if the individuals in that population can disperse over only a small portion of this range, then gene flow across these great distances would be reduced. The occurrence of gradual phenotypic (and genotypic) differences in a population across a large geographical area is called a cline . Successful interbreeding occurs freely at every point along the cline, but individuals at the ends of the cline may not be able to interbreed. This can be tested in the laboratory.
And, on occasions, it is tested in nature. If a cline bends around so that the ends meet, and the populations reunited at the junction cannot interbreed, then the definition of separate species has been met. Such species are called ring species and this type of speciation is called parapatric speciation .
Two examples:
1.
The Caribbean slipper spurge
Euphorbia tithymaloides
.
Genetic analysis shows that this wildflower originated in Central America where Mexico and Guatemala share a common boundary. From there it spread in two directions
- northeast through the Yucatan peninsula and then island-hopped through Jamaica, the Dominican Republic, Puerto Rico and into the Virgin Islands;
- south through Central America, on through Venezuela, and then north through Barbados and the other islands of the Lesser Antilles finally also reaching the Virgin Islands.
Reunited in the Virgin Islands, the two populations have diverged sufficiently that they retain their distinctive genotypic and phenotypic traits. Ongoing studies will determine to what degree they may be reproductively isolated.
2. The large-blotched salamander Ensatina eschscholtzii .
This animal is found in California where it occurs in a number of different subspecies or races. A single subspecies is found in Northern California, and it is thought to be the founder of all the others. Over time that original population spread southward in two directions:
- down the Sierra Nevada mountains east of the great central San Joaquin Valley and
- down the coast range of mountains west of the valley.
South of the valley, the eastern group has moved west and now meets the western group, closing the ring. Here the two populations fail to interbreed successfully, maintaining their distinct identities. But each subspecies interbreeds in an unbroken chain up the two paths their ancestors took.
Ring species present a difficult problem in assigning species designations. It is easy to say that the populations at the ends of the cline represent separate species, but where did one give rise to the other? At every point along the cline, interbreeding goes on successfully.
The same problem faces paleontologists examining the gradual phenotypic changes seen in an unbroken line of ever-younger fossils from what one presumes to be a single line of descent. If one could resurrect the ancestral species (A) and the descendant species (B) and they could not interbreed, then they meet the definition of separate species. But there was no moment in time when one could say that A became B. So the clines of today are a model in space of Darwin's descent with modification occurring over time .
Although clines present a problem for classifiers, they are a beautiful demonstration of Darwin's conviction that the accumulation of small inherited differences can lead to the formation of new species.


4.7: References
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Bates, C. 2016. “When Foot-and-Mouth Disease Stopped the UK in its Tracks” BBC News Magazine. Published online February 17. http://www.bbc.com/news/magazine-35581830
Paarlberg, Philip L., John G. Lee, and Ann H. Seitzinger. 2002. “Potential Revenue Impact of an Outbreak of Foot-and-Mouth Disease in the United States.” Journal of the American Veterinary Medical Association 220(7):988-92.
Paarlberg, Philip L., Ann Hillberg Seitzinger, John G. Lee, and Kenneth H. Mathews, Jr. 2008. Economic Impacts of Foreign Animal Disease. ERR-57. U.S. Dept. of Agriculture, Econ. Res. Serv. Available at: https://www.ers.usda.gov/webdocs/publications/45980/12163_err57fm_1_.pdf?v=41056
Sobekova, K. 2012. Market Analysis of Fresh Berries in the United States University of Arkansas, MS Thesis.
USDA-APHIS. 2013a. “Factsheet: Food-and-Mouth Disease.” Available at: www.aphis.usda.gov/publications/animal_health/2013/fs_fmd_general.pdf
USDA-APHIS. 2013b. “Factsheet: Protecting America From Foot-and-Mouth Disease and Other High-Consequence Livestock Diseases.” Available at: www.aphis.usda.gov/publications/animal_health/2013/fs_fmd_hcd_protection.pdf


6.2: Think Analytically about Cultivating a Growth Mindset
Analytical Thinking
Think analytically to determine how the following concepts relate to cultivating a growth mindset:
- Use of feedback
- Goal setting
- Time management
- Community involvement
- Persistence during stressful times
Analytical Thinking
A nalysis is the process of methodically breaking something down to gain a better understanding of it. Analysis also includes the ability to connect pieces of information as the basis for generalization or explanation.
Essential skills of analysis are the following:
- Breaking down information or artifacts into component parts
- Uncovering relationships among those parts
- Determining motives, causes, and underlying assumptions
- Making inferences and finding evidence to support generalizations
When thinking analytically, determine
- how the parts of something relate to the whole
- how something works
- what something means
- why it’s important
Glossary
analysis : the process of methodically breaking something down to gain a better understanding of it
Contributors and Attributions
CC licensed content, Original
- What Is Analysis? and The Language of Analytic Assignments. Authored by : Karen Forgette. Provided by : University of Mississippi. License : CC BY-SA: Attribution-ShareAlike


1.5: Women, Girls and Armed Conflict
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Chapter 5: Women, Girls and Armed Conflict
Chapter Summary
- Overview
- Profile: Zainab Salbi
- Project: Liberia – Female Peacekeepers Smash Stereotypes
- Questions
- Additional Resources
This chapter discusses the impacts of armed conflict on women and girls, including the renewed social vulnerabilities these conflicts cause.  During times of armed conflict, women are exploited in ways that relate to their reproductive responsibilities or gendered expectations of womanhood. However, women and girls are not merely victims in situations of inter- or intra-state violence. They can have critical perspectives on their position, make choices, and organize collectively. Women can take active roles in violence, such as joining the conflict, or participate in peace processes. The participation of women in formal peace processes is vital for a society to move forward during post-conflict periods, as indicated by the United Nations Security Council Resolution 1325. For example, the chapter mentions that women organized peace campaigns during the 1991 Balkan wars and the 2000 coup d’état in Fiji.
The chapter provides two case studies of women’s engagement in peace processes, one from a non-governmental perspective and another from a state perspective. Women for Women International was founded by Zainab Salbi and aims to help women survivors of war recover from their experiences. The organization has raised over $80 million throughout 17 years and has worked with over 250,000 women and girls. The chapter also discusses the increasing role of female peacekeeping forces. Since 2007, India has sent four Female Formed Police Units (FFPU) to Liberia, which has inspired women to join the national police force. Further, India’s FFPU has inspired Bangladesh and Nigeria to create their own.
Key Terms
- Blue Ribbon Campaign
- Female Formed Police Unit (FFPU)
- United Nations Development Fund for Women (UNIFEM)
- United Nations Security Council Resolution 1325
- Women in Black
- Zainab Salbi
Overview
By Dyan Mazurana
W omen and girls experience armed conflict much the same way men and boys do. They are killed, injured, disabled and tortured. They are targeted with weapons and suffer social and economic dislocation. They suffer the psychosocial impact as loved ones die or they witness violence against their families and neighbors. They suffer the effects of violence before, during and after flight from a combat zone. They are at heightened risk of diseases, including sexually transmitted diseases (STDs) and HIV/AIDS. They are affected by the resource depletion resulting from armed conflict. They join, or are forced to join, armed forces or insurgency movements. They care for the wounded, sick, despairing and displaced, and may be among the most outspoken advocates for peace.
Significant and Lasting Harm
There is a growing body of evidence (ICRC 2001, UNIFEM 2002) that the long-term impact of armed conflict on women and girls may be exacerbated by their social vulnerability. The harm done to women and girls during and after armed conflict is significant, and often exposes them to further harm and violence.  Women are victims of genocide and enslaved for labor. Women and girls are often viewed as culture bearers and reproducers of “the enemy” and thus become prime targets. Women are exploited because of their maternal responsibilities and attachments, which heighten their vulnerability to abuse.
Armed conflicts also have indirect negative consequences that affect agriculture, livelihoods, infrastructure, public health and welfare provision, gravely disrupting the social order. Research shows that these repercussions affect women more adversely than men. As noted by Plümper and Neumayer (2006), while women typically live longer than men in peacetime, armed conflict decreases the gap between female and male life expectancy. Heavily ethnicized conflicts or wars within “failed states” are significantly more damaging to women’s health and life expectancy than other civil wars.
Women as Agents of War and Peace
Women and girls are not merely victims of armed conflict. They are active agents. They make choices, possess critical perspectives on their situations and organize collectively in response to those situations. Women and girls can perpetrate violence and can support violence perpetrated by others. They become active members of conflict because they are committed to the political, religious or economic goals of those involved in violence. This can mean, and has meant, taking up arms in liberation struggles, resistance to occupation or participation in struggles against inequality on race, ethnic, religious or class/caste lines.
Women and girls are also often active in peace processes before, during and after conflicts. Many women know the importance of peace processes and join a variety of grass-roots peace-building efforts aimed at rebuilding the economic, political, social and cultural fabric of their societies. In 1991, as the war in the Balkans was gaining momentum, Women in Black launched an antiwar campaign in the Balkans. In Fiji, as the tensions between Indo-Fijians and indigenous peoples were getting worse, leading to the coup d’état that occurred in 2000, women from both ethnic groups created the Blue Ribbon Campaign peace movement (Anderlini, 2007).
However, formalized processes of peace, including negotiations, accords and reconstruction plans, frequently exclude women’s and girls’ meaningful participation. Too often, women and girls actively involved in rebuilding local economies and civil society are pushed into the background when formal peace processes begin.
Post-Conflict Gains in Gender Relations
Finally, women and girls may gain from the changed gender relations that result from armed conflict. They sometimes acquire new status, skills and power that result from taking on new responsibilities when male heads of household are absent or deceased. These changes in women’s roles can challenge existing social norms. Women’s participation in household decisionmaking, civil society and the local economy and their ownership of land or goods may be altered, sometimes — although not always — to their benefit.
The specific experience of women and girls in armed conflicts greatly depends upon their status in societies before armed conflict breaks out. Where cultures of violence and discrimination against women and girls exist prior to conflict, these abuses are likely to be exacerbated during conflict. Similarly, if women are not allowed to be part of decisionmaking before conflict, it is usually extremely difficult for them to become involved in decisions during the conflict itself or the peace process and post-conflict period. Thus, gender relations in pre-conflict situations as shaped by ethnicity, class, caste and age often set the stage for women’s and girls’ experiences and options during and after armed conflict.
The international community is increasingly aware of and responsive to the impact of armed conflict on women and girls (as shown, for instance, by the unanimous adoption in October 2001 of United Nations Security Council Resolution 1325, which included the special needs of women and girls during repatriation and resettlement, rehabilitation, reintegration and post-conflict reconstruction) and the importance of their participation in peace processes and the post-conflict period. Of paramount importance in any strategy to promote and attain women’s and girls’ rights during and after conflict is a context-specific, grounded understanding of how the conflict has affected different groups of women and their families.
Dyan Mazurana is a research director and associate professor at the Feinstein International Center, Tufts University, where she lectures on women’s and children’s human rights, war-affected civilian populations, armed opposition groups, armed conflict and peacekeeping at the Fletcher School of Law and Diplomacy. Author of four books, numerous articles and reports, she consults for governments, human rights and child protection organizations and U.N. agencies to improve efforts to assist youth and women affected by armed conflict. She has worked in South Asia, the Balkans and sub-Saharan Africa.
PROFILE: Zainab Salbi – Helping Women Recover from War
By Joanna L. Krotz
C harismatic and forthright, Zainab Salbi instantly grabs your attention.
 Over its 17-year history, Women for Women has distributed nearly $80 million in direct aid, microcredit loans and programs serving more than 250,000 women worldwide. Known as a fierce and effective champion, Salbi travels constantly, working with local groups to secure women’s safety and economic prosperity in some of the world’s most devastated regions, including the Democratic Republic of the Congo, Rwanda, Sudan and Afghanistan. Yet little in Zainab Salbi’s fairytale childhood could have foretold such a calling.
Growing up in the privileged precincts of Baghdad, she was the cherished daughter of an elite Iraqi family. Her early years were an idyllic blur of school and family outings, with lessons in piano and ballet. In her best-selling memoir, Between Two Worlds , published in 2005, Salbi describes sunlit days of driving around in the family car alongside her mother, shopping, running errands, paying social calls: “As we drove … along the boulevards lined with palm trees heavy with dates … I took in my city through the passenger-side window — old Baghdad with its dark arcaded souk [market] where men hammered out copper and politics, and the new Baghdad with its cafes and Al-Mansour boutiques.” Most everything Salbi learned in her early years, she writes, came through her adored mother.
Life changed when she turned 11, although it would be years before she could pinpoint the shift. Saddam Hussein assumed power and soon anointed Salbi’s father, a commercial aviator, as the ruler’s personal pilot. Increasingly, through Salbi’s teenage years, the family felt the effects of Saddam’s regime, both his patronage and his oppressive heel. She recalls halcyon weekends at Saddam’s compound, calling him “Amo” or “Uncle,” playing with his kids around the pool and, as she was constantly cautioned, willfully ignoring the fear and violence rising around her. Later, living in the United States, particularly after the September 11, 2001, terrorist attacks, that intimacy with Saddam would haunt her. “I kept it a secret and told no one,” she says. “I was afraid if I told people I knew Saddam, my face would be erased and all anyone would see in me was Saddam.”
When Salbi was 19, her progressive mother suddenly announced that she’d arranged a marriage for Salbi to a much older Iraqi banker living in America. “It was very painful,” says Salbi. “My mother had always told me not to depend on any man. She was passionate, adamant about it. Then all of a sudden I was being whisked away from home. I had no idea what she was talking about.” Twenty years on, you still hear the hurt, the loss and indignation in Salbi’s voice. Dutifully, Salbi went off to be a bride in Chicago.
And she landed in a nightmare. “The man who was my husband turned out to be abusive,” she says. When Salbi proved unbowed, he raped her. She walked out after three months. “I had $7 in my pocket, some designer clothes on my back and about $20 a week from family funds to survive,” she says.
It was 1990 and Saddam had just invaded Kuwait. After Operation Desert Storm was launched, there was no going home to Iraq for Salbi.
Over time, she built a life in the United States. It was years before she saw her family again. And years after that, when her mother was ill and dying, that Salbi finally found the voice to ask why she’d been sent away.  The only escape route from becoming Saddam’s plaything was an arranged marriage on another continent.
In 1993, Salbi was living in Washington, remarried to a Palestinian student named Amjad Atallah, when she read a news story about the Bosnian war and rape camps where some 20,000 women were raped. The couple decided to travel to Bosnia to help.
Salbi and Atallah returned to Washington determined to find a group that would provide aid for Bosnian rape victims. But none existed. So, still on a student budget, the couple founded their own organization, Women for Women, and began to help the women in the Balkans.
By 2004, Salbi, now divorced, had expanded Women for Women to its international mission. Appearances on the Oprah Winfrey Show , which draws millions of viewers, boosted both her profile and the organization as donations climbed. In the 15 years since arriving in the United States, Salbi became a prominent humanitarian and an award-winning women’s rights advocate, honored by President Bill Clinton for her work in Bosnia. What hadn’t changed were her secrets about Saddam and her first marriage.
On a trip to the eastern Congo that year, Salbi was interviewing a woman named Nabito, then age 52. Rebels had raped Nabito and her three daughters. “There were so many she said she couldn’t tell how many were around and how many had raped her,” says Salbi, remembering. Salbi asked Nabito whether she wanted her story kept quiet. Instead, says Salbi, “she said, ‘If I could tell my story to the whole world, I would, so other women would not have to go through what I’ve gone through. So you go and tell my story.’”
Nabito’s courage — and her resilient conviction — pushed Salbi into breaking her own silence. Owning her past also has changed the way Zainab Salbi works. “Before, I’d be the humanitarian worker with connections and aid interviewing other women. Now, I am their equal. I’m not there to save anyone. I actually am one of the women I’m trying to help.”
Joanna L. Krotz is a multimedia journalist and speaker whose work has appeared in the New York Times , Worth , Money and Town & Country and on MSN and Entrepreneurship.org . She is the author of The Guide to Intelligent Giving and founder of the Women’s Giving Institute, an organization that educates donors about strategic philanthropy.
PROJECT: Liberia – Female Peacekeepers Smash Stereotypes
By Bonnie Allan
Since its groundbreaking deployment in 2007, India has sent four all-female police units to Liberia, each serving a one-year rotation. Their success in the postwar country has inspired other nations to defy tradition and deploy more female troops in U.N. peacekeeping roles.
F ive days after an elaborate marriage ceremony in southern India, 28-year-old Rewti Arjunan traded her red silk sari for a blue camouflage police uniform and flew to the West African country of Liberia.
The young bride is serving in one of the world’s few all-female police units deployed to a United Nations peacekeeping mission.
“In India, we are quite traditional with these things. My husband, he was against it,” admits Arjunan, who had never before traveled outside India. The trained police officer gave her future husband an ultimatum.
“I told him, ‘If you permit me to go on this mission, I will marry you.’”
Now, Arjunan’s life is anything but traditional. She is helping to change the face of international policing in a post-conflict country.
Since its groundbreaking deployment in 2007, India has sent four Female Formed Police Units (FFPU) to Liberia, each serving a one-year rotation. More than 100 female police officers trained in crowd control and conflict resolution make up the FFPU at any one time. They are supported by about two dozen men who serve as drivers, cooks and logistical coordinators.
The FFPU is primed for rapid response to any violence that might erupt in this country of 3.8 million, which still lacks a strong army or armed police force.

Eight years after the war ended, almost 9,500 U.N. peacekeepers help maintain the fragile peace.
“The greatest deed is to protect humanity. I got this chance, and I thought, ‘I want to live this,’” says Arjunan.
The Female Formed Police Unit is a symbol of progress for U.N. Security Council Resolution 1325 on women, peace and security, which stipulates that peacekeeping missions support women’s participation in post-conflict peace building.
The United Nations’ ultimate goal is gender parity in the civilian, military and police sectors, but, globally, women make up just 8.2 percent of roughly 13,000 U.N. police and only two percent of military police.
India has scored high marks for pioneering an all-female police unit, serving alongside other female officers from Nigeria and elsewhere, in a country that boasts Africa’s first female head of state, Ellen Johnson Sirleaf.
By day, the Indian police officers stand in the hot sun guarding the president’s office, and, by night, they patrol crime-ridden areas of the capital, Monrovia.
As the rain trickles down on the dark streets of Monrovia’s Congo Town, Arjunan sits in the back seat of a U.N. police vehicle with her hair tucked inside a blue beret and a pistol strapped to her waist. Beside her, 25-year-old Pratiksha Parab holds an AK-47 rifle and peers out the window.
Their job is to protect Liberia National Police (LNP) officers, who are not armed, as they patrol to deter armed robberies and rape. “Most of the violent crimes are at night, and the criminals use weapons,” says LNP Commander Gus Hallie. “So, with our FFPU counterparts on our side, with arms, we feel we can battle with criminals.”
As they patrol, the U.N. police observer and the LNP officer joke that “Indian women are tough.” Arjunan smiles, pleased, but she explains why she is a good peacekeeper.
“Women are not aggressive. We come in a polite way. This presence can maintain the peace. We are loving by nature.”
There are many stereotypes attached to female peacekeepers: more nurturing, more communicative, less intimidating. The label that makes Contingent Commander Usher Kiran cringe, though, is “soft.”
“I don’t think there is a difference between female and male,” says Kiran, a 22-year police veteran, as she sits under a poster of Mahatma Gandhi.
“If you are putting on the same uniform, you are doing the same duty, you are having the same authority as the males.”
“Where we found a difference [between male and female peacekeepers] is in their perceptions of their role,” explains the U.N.’s gender adviser in Liberia, Carole Doucet. “The women see themselves as more broadly involved in the community.”
Doucet says the U.N.’s female police, known as “blue helmettes,” have inspired Liberian women to join the national police force. In 2007, only six percent of Liberia’s police were women. Today, that proportion has risen to 15 percent, with roughly 600 female officers.
The Indian women also sponsor an orphanage, teach self-defense and computer classes to local women, and — despite limited English — reach out to survivors of sexual abuse.
“I can be scared to talk to a man,” whispers a 16-year-old rape victim, who cannot be identified, at a safe home for girls in Monrovia. “A woman is better. She is like an auntie or mother.”
India’s all-female unit has inspired Bangladesh and Nigeria to create their own, while countries such as Rwanda and Ghana also are ramping up their female troop contributions to U.N. missions. Back at the Indian headquarters in Monrovia, Arjunan talks to her new husband over the Internet, using a webcam, for at least an hour every day. Although she’s a little homesick, Arjunan says she is proud to follow in the footsteps of other courageous women in India’s history.
“Many freedom fighters were ladies … fighting for justice. Fighting for good things.”
Bonnie Allan is a freelance journalist working in Liberia, West Africa. She worked as a journalist in Canada for more than a decade and holds a master’s degree in international human rights law from the University of Oxford.
Multiple Choice Questions
Questions
-
Examples of violence against women during armed conflict include…
- Rape
- Forced marriage
- Forced impregnation
- Torture
- All of the above
-
Reasons for women’s vulnerability during armed conflict mentioned in the chapter include…
- Women may be viewed as reproducers of the ‘enemy’ due to their maternal responsibilities
- Indirect negative consequences on agriculture, welfare provision, and infrastructure, which research shows has disproportionate impacts on the lives of women
- Many women lose their high-level government positions as the state disintegrates
- The gap between male and female expectancy increases
- Both A and B
-
Women may also be active agents in conflict through actions such as…
- Taking up arms in struggles
- Involvement in decision-making mechanisms during peace processes
- Occupying a higher position of power in post-conflict periods
- Working to ensure that their social and household roles are not changed by periods of conflict
- All of the above
-
Which United Nations Security Council Resolution (UNSC) included the importance of women’s participation in peace processes and the post-conflict period?
- UNSC Resolution 1333
- UNSC Resolution 1325
- UNSC Resolution 589
- UNSC Resolution 1034
- None of the above
-
Women for Women International was founded by…
- Angelia Jolie Pitt
- Hillary Clinton
- Vandana Shiva
- Zainab Salbi
- None of the above
-
Salbi was motivated by which conflict to create Women for Women International?
- Bosnian War
- Rwandan Civil War
- Gulf War
- Somali Civil War
- None of the above
-
The first Female Formed Peacekeeping Unit (FFPU) was assembled by…
- Canada
- United States
- Germany
- India
- South Africa
-
Some stereotypes of female peacekeepers include…
- More nurturing
- More communicative
- Less intimidating
- All of the above
- None of the above
-
The country that produced Africa’s first female head of state is…
- Namibia
- Botswana
- Liberia
- Lesotho
- None of the above
-
According to the chapter, which is an accurate difference between male and female peacekeepers?
- Female peacekeepers are less intimidating
- Male peacekeepers have more physical strength
- Female peacekeepers are likely to view their role as more community oriented
- Male peacekeepers are less nurturing
- All of the above
-
In 2007, what percentage of Liberian peacekeepers were women?
- 6%
- 5%
- 20%
- 15%
- 10%
-
What other countries formed FFPUs or increased their female presence in peacekeeping missions after India’s first delegation?
- Canada, Australia, New Zealand, and Portugal
- Bangladesh, Nigeria, Rwanda, and Ghana
- Brazil, Russia, Argentina, and Britain
- China, Japan, Korea, and Singapore
- None of the above
Answers
- The correct answer is E (all of the above).
- Both answers A and B are correct. Women may be viewed as producers of the ‘enemy’ due to their maternal responsibilities (answer A) and are indirectly affected by damages to agriculture, welfare provision, and infrastructure (answer B). The chapter does not mention that women lose high-level government positions (answer C), and because women on average live longer than men , the gap between male and female life expectancy decreases when women are adversely affected by armed conflict, rather than increasing (answer D).
- The correct answer is E. All the answers are attested as ways women assert agency in periods of conflict, although none are universal. Women may commit violence during conflict for various reasons, although in other situations they may avoid armed conflict (answer A). Women are sometimes involved in peace processes (answer B), but are too often pushed to the side. Women may occupy higher positions of power in post-conflict situations, but this depends on many factors, notably their position of power prior to when the conflict began (answer C). The role of women in their societies may change during conflict, or remain relatively similar, but neither is guaranteed (answer D).
- The correct answer is UNSC Resolution 1325 (answer B). UNSC 1333 called for a ban on all military assistance to the Taliban and closure of its camps in the year 2000 (answer A). UNSC 589 condemned the oppressive politics of South Africa’s apartheid system in the year 1985 (answer C). UNSC Resolution 1034 discussed violations of international humanitarian law in the former Yugoslavia (1995) (answer D).
- The correct answer is Zainab Salbi (answer D). Angelina Jolie Pitt (answer A) is an American actress who was appointed UNHCR Special Envoy in 2012. Hillary Clinton was the 2009 – 2013 U.S. Secretary of State and 2016 presidential candidate for the Democratic Party (answer B). Vandana Shiva is an Indian scholar, anti-globalization activist, and all around environmentalist (answer C).
- The correct answer is Bosnian War (answer A).
- The correct answer is India (answer D).
- The correct answer is all of the above (answer D).
- The correct answer is Liberia (answer C).
- Answer C is correct. Carle Doucet, the UN’s gender adviser in Liberia, stated that the women involved saw their role as more broadly involved in the community.
- The correct answer is 6% (answer A).
- The correct answer is B. India’s all-female unit has inspired Bangladesh and Nigeria to create their own, while countries such as Rwanda and Ghana have ramped up their female troop contributions.
Discussion Questions
- How are women specifically vulnerable during periods of armed conflict?
- What is the connection between armed conflict, failed states, and violence against women? Is a strong state needed to ensure that women’s rights are protected?
- Look beyond the chapter to find some examples of women’s active involvement in combating violence against women. Please use examples from both the global South and the global North.
- Are there any challenges posed by the global influence of Western or American women’s rights organization?
- What are the strengths and limitations of Resolution 1325 in increasing the role of women in peacekeeping?
- Please offer an example of when and where Resolution 1325 was used. (Outside research)
- What would be some explanations for why a peace process did not lead to a post-conflict situation which improved the status of women?
Essay Questions
- How are women specifically vulnerable during periods of armed conflict?
- What is the connection between armed conflict, failed states, and violence against women? Is a strong state needed to ensure that women’s rights are protected?
- Look beyond the chapter to find some examples of women’s active involvement in combating violence against women. Please use examples from both the global South and the global North.
- Are there any challenges posed by the global influence of Western or American women’s rights organization?
- What are the strengths and limitations of Resolution 1325 in increasing the role of women in peacekeeping?
- Please offer an example of when and where Resolution 1325 was used. (Outside research)
- What would be some explanations for why a peace process did not lead to a post-conflict situation which improved the status of women?
Additional Resources
Bacon, L.
“Reform: Improving Representation and Responsiveness in a Post-Conflict Setting.”
Journal of International Peacekeeping
4, 372 – 397: (2015).
Explores efforts by the Liberian National Police to enhance training to address sexual and gender-based violence and increasing female officers.
http://dx.doi.org/10.1080/13533312.2015.1059285
Gaestel, A. & Shelly, A.
Female UN Peacekeepers: an all-too-rare sight.
Guardian.
(2015).
Re-examines the progress made on realizing the United Nations Security Council Resolution 1325.
Gogali, L.
TEDXUbud. “Indonesian Women’s Empowerment in a Post-Conflict Society.” (2011).
TED Talk about women’s active protection of the family, organizing across ethnic and religious lines, and grassroots involvement in the peace process in post-conflict Indonesia.
https://www.youtube.com/watch?v=-i9unT9aZ8E
Hansson, J. & Hendriksson, Malin . “Western NGOs Representation of “Third World Women: A Comparative Study of Kvinna till Kvinna (Sweden) and Women for Women International (USA).” University West. (2016).
http://www.diva-portal.org/smash/get/diva2:632032/fulltext01.pdf
Heathcote, G.
“Lecture: The Protection of Civilians and Protection of Peacekeeping Mandates: Gender and Ethics in Collective Security.”
Feminists @ Law 5
(2): (2015).
Critiques the UN Security Council Resolutions on Women, Peace and Security to illustrate how feminist ethics are used to justify new methods of violence.
http://journals.kent.ac.uk/index.php/feministsatlaw/article/view/236
Noisi, C. O. & Farrugia, M.
“A Long Road Ahead: Integrating Gender Perspectives into Peacekeeping Operations.”
OpenDemocracy
. (2014).
Examines gender norms and perspectives that have led to gaps implementing UN Resolution 1325.
Restrepo, E. M.
“Leaders Against All Odds: Women Victims of Conflict in Colombia.”
Palgrave Communications 2
, 1 – 11: (2016).
Highlights the capacity of women who have been victims of violence to be agents of peace and reconciliation.
http://www.palgrave-journals.com/articles/palcomms201614
Prenzler, T. & Sinclair, G
. The Status of Women Police Officers:
An International Review. International Journal of Law, Crime and Justice
41(2), 115 – 131: (2013).
Reports on a survey on the status of women police officers from 23 locations globally.
http://dx.doi.org/10.1016/j.ijlcj.2012.12.001
United Nations Peacekeeping
. “Gender and Peacekeeping.”
Main United Nations resource with further information on gender and peacekeeping.
www.un.org/en/peacekeeping/issues/women/


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cultural sensitivity
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recognizing and acknowledging that cultural differences exist among people and showing respect and appreciation for others' beliefs, values, practices, and perspectives
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dentures
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artificial teeth not permanently implanted
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gingivitis
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inflammation of the gums or gingivae
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halitosis
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persistent foul-smelling or bad breath
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hygiene
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the measures or practices conducive to preserving health and preventing disease, particularly through cleanliness
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medical asepsis
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techniques and procedures used to decrease the potential for the spread of microorganisms and infection
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oral hygiene
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care of the oral cavity
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otitis externa
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an infection or inflammation of the external ear canal, usually caused by water exposure or bacterial/fungal infections
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pediculosis
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lice infestation
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periodontitis
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marked inflammation of the gums that also involves degeneration of the dental bone and tissues
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personal hygiene
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self-care measures one performs to preserve their own health
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pinworm
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an intestinal worm that usually spreads when an infected individual scratches the anal area
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ringworm
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a fungal infection of the skin or scalp
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scabies
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a contagious skin infestation caused by a burrowing mite accompanied by extreme itching
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sebum
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an oily secretion of the sebaceous gland
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skin breakdown
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the damage or injury that occurs to the skin and underlying tissue due to prolonged pressure, friction, shear, or moisture
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tooth decay
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visible cavities or holes in the outer sruface of a tooth or enamel
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trachoma
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a bacterial infection of the eyes
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urinary tract infection
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an infection of any part of the urinary system (urethra, bladder, or kidneys)


1.10.32: Gibbs Energies- Liquid Mixtures- Typically Aqueous (TA)
For many binary aqueous liquid mixtures, the pattern shown by the molar excess thermodynamic parameters is \(\mathrm{G}_{\mathrm{m}}^{\mathrm{E}}>0\); \(\left|\mathrm{T} \, \mathrm{S}_{\mathrm{m}}^{\mathrm{E}}\right|>\left|\mathrm{H}_{\mathrm{m}}^{\mathrm{E}}\right|\). This pattern of excess molar properties defines TA mixtures. \({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\) is positive because the excess molar entropy of mixing is large in magnitude and negative in sign. In these terms mixing is dominated by the entropy change. The excess molar enthalpy of mixing is smaller in magnitude than either \({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\) or \(\mathrm{T} \, {\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\) but exothermic in water-rich mixtures.
The word ‘Typically’ in the description stems from observation that this pattern in thermodynamic variables is rarely shown by non-aqueous systems. At the time the classification was proposed [1], most binary aqueous liquid mixtures seemed to follow this pattern. Among the many examples of this class of system are aqueous mixtures formed by ethanol, 2-methyl propan-2-ol and cyclic ethers including tetrahydrofuran[2]. In water-rich mixtures, a large in magnitude but negative in sign \(\mathrm{T} \, {\mathrm{S}_{\mathrm{m}}}^{\mathrm{E}}\) produces a large (positive) \({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\). For mixtures rich in the apolar component m endothermic mixing produces a positive \({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\). The key point is that in m water-rich mixtures a positive \({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\) emerges from a negative \(\mathrm{T} \, {\mathrm{S}_{\mathrm{m}}}^{\mathrm{E}}\).
With reference to volumetric properties of these system, the partial molar volume \(\mathrm{V}(\mathrm{ROH})\) for monohydric alcohols can be extrapolated to infinite dilution; i.e. \(\operatorname{limit}\left(\mathrm{x}_{2} \rightarrow 0\right) \mathrm{V}(\mathrm{ROH})=\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})^{\infty}\) where \(x_{2}\) is the mole fraction of alcohol. The difference, \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})^{\infty}-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) is negative. In fact this pattern is observed for both TA and Typical Non-aqueous binary aqueous mixtures. Examples where this pattern is observed included aqueous mixtures formed by DMSO, \(\mathrm{H}_{2}\mathrm{O}_{2}\) and \(\mathrm{CH}_{3}\mathrm{CN}\). Significantly \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) is negative for TA mixtures, decreasing from \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})^{\infty}-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) with increase in mole fraction of \(\mathrm{ROH}\), accompanying by a tendency to immiscibility. The initial decrease in \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) with increase in \(x_{2}\) is more dramatic the more hydrophobic the non-aqueous component; for 2-methyl propan-2-ol aqueous mixtures at \(298.2 \mathrm{~K}\) and ambient pressure, the minimum occurs at an alcohol mole fraction 0.04 (at \(298.2 \mathrm{~K}\)).
Many explanations have been offered for the complicated patters shown by the dependence of \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) on mole fraction composition.
In one model, the negative \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) at low mole fractions of \(\mathrm{ROH}\) is accounted for in terms of a liquid clathrate in which part of the hydrophobic R-group ‘occupies’ a guest site in the water lattice. The decrease in \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) is accounted for in terms of an increasing tendency towards a clathrate structure. But with increase in \(x_{2}\) there comes a point where there is insufficient water to construct a liquid clathrate water host. Hence \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) increases.
An important characteristic of TA mixtures is a tendency towards and in some cases actual decrease in liquid miscibility with increase in temperature. At ambient \(\mathrm{T}\) and \(\mathrm{p}\), the mixture 2-methyl propan-2-ol + water is miscible (but only just!) in all molar proportions. The corresponding mixtures prepared using butan-1-ol and butan-2-ol are partially miscible. TA systems are therefore often characterised by a Lower Critical Solution Temperature LCST. In fact nearly all examples quoted in the literature of systems having an LCST involve water as one component; e.g. \(\mathrm{LCST} = 322 \mathrm{~K}\) for 2-butoxyethanol + water [3]. This tendency to partial miscibility is often signalled by the properties of the completely miscible systems.
Returning to the patterns shown by relative partial molar volumes, \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\), a stage is reached whereby with increase in mole fraction of the non-aqueous component, this property increases after a minimum. Other properties of the mixtures also change dramatically including a marked increase in \(\left(\alpha_{a} / v^{2}\right)\) where \(\alpha_{\mathrm{a}}\) is the amplitude attenuation constant and \(ν\) is the frequency of the sound wave in the MHz range; e.g. \(70 \mathrm{~MHz}\). Actually the pattern is complicated. Over the range of mixture mole fractions \(x_{2}\) where \(\left[\mathrm{V}(\mathrm{ROH} ; \mathrm{aq})-\mathrm{V}^{*}(\mathrm{ROH} ; \ell)\right]\) decreases with increase in \(x_{2}\), the ratio \(\left(\alpha_{a} / v^{2}\right)\) hardly changes although the speed of sound increases. At a mole fraction \(x_{2}\) characteristic of the temperature and the non-aqueous component, \(\left(\alpha_{a} / v^{2}\right)\) increases sharply, reaching a maximum where the mixture has a strong tendency to immiscibility. This interplay between in-phase and out-of-phase components of the complex isentropic compressibility when the mole fraction composition of the mixture is changed highlights the molecular complexity of these systems. By way of contrast the ratio \(\left(\alpha_{a} / v^{2}\right)\) for DMSO + water mixtures (a TNAN system) changes gradually when the mole fraction of DMSO is changed.
For TA mixtures where \(\left(\alpha_{a} / v^{2}\right)\) is a maximum [4], other evidence points to the fact these mixtures are micro-heterogeneous; cf. excess molar isobaric heat capacities. Phase separation of the mixture 2-methyl propan-2-ol is observed when butane gas is dissolved in the liquid mixture. The miscibility curve shows an LCST near \(282 \mathrm{~K}\) [5].
Footnotes
[1] F. Franks in Hydrogen-Bonded Solvent Systems, ed. A. K. Covington and P. Jones, Taylor and Francis, London,1968, pp.31-47.
[2] The following references refer to properties of TA binary liquid mixtures.
-
alcohol + water mixtures. Isobaric heat capacities.
- H. Ogawa and S. Murakami, Thermochim. Acta, 1986, 109 ,145.
- G. I. Makhatadze and P. L. Privalov, J. Solution Chem.,1989, 18 ,927.
- R. Arnaud, L. Avedikian and J.-P. Morel,J. Chim. Phys., 1972,45.
-
fluoroalkanol + water mixtures.
-
\({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\)
R. Jadot and M.Fralha,J. Chem.Eng. Data,1988,33,237.
J. Murto and A. Kiveninen, Suomen Kemist. Ser. B, 1967,40,258. -
Enthalpies
M. Denda, H. Touhara and K. Nakanishi, J. Chem. Thermodyn., 1987, 19 ,539.
A. Kivinen, J. Murto and A.Vhtala, Suomen Kemist.1967, 40 ,298. - Volumes; J. Murto, A. Kivinen, S. Kivimaa and R. Laakso, Suomen Kemist., Ser. B, 1967, 40 ,250.
-
\({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\)
-
amine + water mixtures
- \({\mathrm{X}_{\mathrm{m}}}^{\mathrm{E}}\) and miscibility; J. L. Copp and D. H. Everett, m Discuss. Faraday Soc.,1953, 15 ,174.
- Et3N + water; miscibility; A. Bellemans, J.Chem.Phys.,1953, 21 , 368.
-
THF + water
-
\({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\)
J. Matous, J. P. Novak, J. Sobr and J. Pick, Collect. Czech. Chem.Commun.,1972, 37 ,2653.
C. Treiner, J.-F. Bocquet and M. Chemla, J. Chim..Phys., 1973, 70 , 72. -
\({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\) for \(\mathrm{THF} + \mathrm{~D}_{2}\mathrm{O}\);
J. Lejcek, J. Matous, J. P. Novak and J. Pick, J. Chem. Thermodyn., 1975, 7 ,927. -
Vapour composition;
W. Hayduk, H. Laudie and O. H. Smith, J. Chem.Eng Data,1973, 18 ,373. -
\({\mathrm{H}_{\mathrm{m}}}^{\mathrm{E}}\)
H. Nakayama and K. Shinoda, J. Chem. Thermodyn., 1971, 3 ,401. -
Activity of water
K. L. Pinder, J. Chem. Eng. Data, 1973, 18 ,275. -
Thermal expansivities
O. Kiyohara, P. J. D’Arcy and G. C. Benson, Can. J. Chem., 1978, 56 ,2803. -
\({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\) and \({\mathrm{V}_{\mathrm{m}}}^{\mathrm{E}}\).
Signer, H. Arm and H. Daeniker, Helvetica Chimica Acta, 1969, 52 , 2347. -
2-Methyl propan-2-ol + water
In the chemical literature, 2-methyl propan-2-ol is often called t-butanol but as Prof. David J. G. Ives often pointed out, there is no organic compound, t-butane. -
\({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\) and \({\mathrm{H}_{\mathrm{m}}}^{\mathrm{E}}\)
Y. Koga, W. W. Y. Siu and T. Y. H. Wong, J. Phys. Chem., 1990, 94 ,7700. -
Enthalpies
Y. Koga, Can. J.Chem.,1986, 64 ,206;1988, 66 ,1187,3171. -
Volumes
A. Hvidt, R. Moss and G. Nielsen, Acta Chem. Scand.,Sect. B, 1978, B32 , 274.
M. Sakurai, Bull. Chem. Soc. Jpn.,1987, 160 ,1. -
\(\mathrm{C}_{\mathrm{p}}\) and \(\mathrm{V}\)
B. de Visser, G. Perron, and J. E. Desnoyers, Can J. Chem.,1977, 55 ,856. -
X-ray scattering
K. Nishikawa, Y. Kodera and T. Iijima, J. Phys. Chem., 1987, 91 ,3694. -
Sound velocity
H. Endo and O. Nomoto,Bull. Chem. Soc. Jpn., 1973, 46 , 3004. -
Isentropic compressibilities;
J. Lara and J. E. Desnoyers, J. Solution Chem., 1981, 10 ,465. - Propan-1-ol + water
-
\({\mathrm{V}_{\mathrm{m}}}^{\mathrm{E}}\)
G. C. Benson and O. Kiyohara, J. Solution Chem.,1980, 9 ,791.
M. I. Davis, Thermochim. Acta, 1990, 157 ,295.
C. De Visser, G. Perron and J. E. Desnoyers, Can. J.Chem.,1977, 55 ,856. -
Propanone + water \({\mathrm{X}_{\mathrm{m}}}^{\mathrm{E}}\) references;
M. J. Blandamer, N. J. Blundell, J. Burgess, H. J. Cowles and I. M. Horn, J. Chem. Soc. Faraday Trans.,1990, 86 ,283. -
Methyl vinyl ketone + water
LCST = \(301 \mathrm{~K}\); UCST = \(356 \mathrm{~K}\); J. Vojtko and M.Cihova, J. Chem. Eng. Data, 1972, 17 ,337.
-
\({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\)
[3] F. Elizalde, J Gracia and M. Costas, J Phys.Chem.,1988, 93 ,3565.
[4] M. J Blandamer and D. Waddington, Adv. Mol. Relax.Processes,1970, 2 ,1.
[5] R. W. Cargill and D. E. MacPhee, J. Chem. Soc. Faraday Trans.1, 1989, 85 , 2665; an excellent observation!
[5] \({\mathrm{G}_{\mathrm{m}}}^{\mathrm{E}}\); M. J. Blandamer, J. Burgess, A. Cooney, H. J. Cowles, I. M. Horn, K. M. Martin, K.W. Morcom and P. Warrick, J. Chem. Soc. Faraday Trans., 1990, 86 , 2209.