Quiz

QUIZ

1. What most affects the vapor pressure of a liquid?

a. Its polarity b. Its temperature c. Its volume d. Its melting point

Answer: b. The temperature of a liquid will increase the vapor pressure of a liquid.

2. What is the point at which a liquid is in equilibrium with its vapor at a partial pressure of 760 torr called?

a. Critical point b. Vapor pressure c. Normal boiling point d. Freezing point

Answer: c. The normal boiling point is the point at which a liquid is in equilibrium with its vapor at 760 torr or one atmosphere of partial pressure.

3. What is not an equivalent number at 100 degrees and 760 torr?

a. Condensation point b. Boiling point c. Dew point d. Critical point

Answer: d. Each of these is the same value under the conditions of 100 degrees and 760 torr with the exception of the critical point where there is no possibility to have the gas become liquid.

4. What does the superheating of water involve?

a. Raising the temperature so all of the liquid boils off. b. The raising of the temperature above the critical point of water. c. The raising of the temperature of water above its boiling point. d. The raising of solid water above its melting point.

Answer: c. Superheating of water involves raising its temperature above its boiling point, which usually requires increasing the pressure circumstances of the water being superheated.

5. What is the critical point of water?

a. 0 degrees Celsius b. 100 degrees Celsius c. 374 degrees Celsius d. 742 degrees Celsius

Answer: c. The critical point of water is 374 degrees, above which it is a superfluid rather than a liquid or gaseous substance.

6. A phase diagram for an element is a function of what two factors?

a. Pressure and Temperature b. Pressure and boiling point c. Temperature and sublimation point d. Boiling point and volume

Answer: a. There is a relationship between temperature and pressure, which creates the phase diagram for all substances in nature.

7. Surface tension of liquid can be described as what it takes to break the surface of the liquid by another force. What is the SI unit for surface tension?

a. Joules b. Joules per liter c. Joules per square meter d. grams per square meter

Answer: c. This is the energy that it takes to break the surface of a liquid; it is described as the energy per square area or, in the case of SI units, it is joules per square meter.

8. What property of water is most affected by surfactants?

a. Surface tension b. Viscosity c. Boiling point d. Capillary action

Answer: a. Surfactants interfere with the intermolecular forces and can therefore reduce the surface tension of water, making these substances good for firefighting and in using water for cleaning.

9. With ion-dipole interactions between ions and polar molecules like water, what is the relationship between the strength of the interaction and the distance between the molecules?

a. There is a positive relationship between the two that is linear. b. There is a negative relationship between the two that is linear. c. There is a positive relationship between the two that is nonlinear. d. There is a negative relationship between the two that is nonlinear.

Answer: d. There is a negative relationship between the two that is nonlinear. The interaction falls off with increasing distance in a nonlinear fashion. This is because of the inverse square law.

10. Which type of intermolecular force is the weakest?

a. dipole-dipole forces b. dipole-ion forces c. ion-ion forces d. They are roughly the same

Answer: a. Dipole-dipole forces are the weakest of those listed, falling off by a factor of r to the sixth power, where r is the distance between the molecules.