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General Chemistry Principles, Patterns, and Applications, 2011

General Chemistry Principles, Patterns, and Applications, 2011

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2. How is the environment of molecules on the surface of a liquid droplet different from that of molecules in<br />

the interior of the droplet? How is this difference related to the concept of surface tension?<br />

3. Explain the role of intermolecular <strong>and</strong> intramolecular forces in surface tension.<br />

4. A mosquito is able to walk across water without sinking, but if a few drops of detergent are added to the<br />

water, the insect will sink. Why?<br />

5. Explain how soaps or surfactants decrease the surface tension of a liquid. How does the meniscus of an<br />

aqueous solution in a capillary change if a surfactant is added? Illustrate your answer with a diagram.<br />

6. Of CH 2 Cl 2 , hexane, <strong>and</strong> ethanol, which has the lowest viscosity? Which has the highest surface tension?<br />

Explain your reasoning in each case.<br />

7. At 25°C, cyclohexanol has a surface tension of 32.92 mN/m 2 , whereas the surface tension of cyclohexanone,<br />

which is very similar chemically, is only 25.45 mN/m 2 . Why is the surface tension of cyclohexanone so much<br />

less than that of cyclohexanol?<br />

8. What is<br />

the relationship between<br />

a. surface tension <strong>and</strong> temperature?<br />

b. viscosity <strong>and</strong> temperature?<br />

Explain your answers in terms of a microscopic picture.<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

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