Question 1

Which of the following statements best explains why water has a much higher boiling point than methane ($$\mathrm{CH_4$}) $$despite their similar molar masses?

Accepted Answer

Water molecules form strong hydrogen bonds, which require more energy to break during boiling.

Question 2

A liquid in a sealed container is at equilibrium with its vapor. What will happen to the vapor pressure if the temperature is increased?

Accepted Answer

The vapor pressure will increase because more molecules have enough energy to escape into the vapor phase.

Question 3

Which of the following phase changes is exothermic?

Accepted Answer

Freezing

Question 4

The enthalpy of vaporization ($$\Delta H_{vap}) $$for water is $$40.7\ \mathrm{kJ/mol}. $$How much energy is required to vaporize $$36.0\ \mathrm{g} of $$water at its boiling point?

Accepted Answer

$$81.4\ \mathrm{kJ}$$

Question 5

Which of the following substances would have the highest vapor pressure at room temperature?

Accepted Answer

Diethyl ether ($$\mathrm{C_2H_5OC_2H_5})$$

Question 6

Which equation correctly relates the vapor pressure of a liquid to its mole fraction in a solution according to Raoult's Law?

Accepted Answer

$$P_{solution} = X_{solvent} \cdot P^\ast_{solvent}$$

Question 7

A sample of benzene has a vapor pressure of $$100.0\ \mathrm{mmHg} at$$ $$26.1^\circ\mathrm{C}$$ and $$400.0\ \mathrm{mmHg} at$$ $$80.1^\circ\mathrm{C}. $$What is the boiling point of benzene at $$760\ \mathrm{mmHg}$$?

Accepted Answer

$$80.1^\circ\mathrm{C}$$

Question 8

Which of the following best describes the process of capillary action?

Accepted Answer

The ability of a liquid to flow up a narrow tube against gravity due to adhesive and cohesive forces.

Question 9

Which of the following phase transitions skips the liquid phase?

Accepted Answer

Sublimation

Question 10

A heating curve for water shows a plateau at $$100^\circ\mathrm{C}. $$What is happening to the water during this plateau?

Accepted Answer

The water is undergoing a phase change from liquid to gas, and energy is being used to break intermolecular forces.

Question 11

Which of the following correctly ranks the intermolecular forces from weakest to strongest?

Accepted Answer

London dispersion \u003c dipole-dipole \u003c hydrogen bonding

Question 12

Which of the following statements about surface tension is correct?

Accepted Answer

Surface tension increases as intermolecular forces become stronger.

Question 13

Which of the following best describes the triple point on a phase diagram?

Accepted Answer

The temperature and pressure at which solid, liquid, and gas phases coexist in equilibrium.

Question 14

Which of the following phase changes is endothermic?

Accepted Answer

Vaporization

Question 15

A sample of ethanol vapor at $$100^\circ\mathrm{C} is $$allowed to condense to liquid at $$80^\circ\mathrm{C}. $$Which equation would you use to calculate the total heat released?

Accepted Answer

$$q = m \cdot \Delta H_{cond} + m \cdot C_{liquid} \cdot \Delta T$$

Question 16

Which of the following would increase the boiling point of a liquid?

Accepted Answer

Increasing the strength of intermolecular forces

Question 17

Which of the following best explains why the fusion curve for water has a negative slope on its phase diagram?

Accepted Answer

Ice is less dense than liquid water, so increasing pressure favors the liquid phase.

Question 18

Which of the following best describes the relationship between temperature and average kinetic energy of molecules?

Accepted Answer

As temperature increases, the average kinetic energy of molecules increases.

Question 19

Which of the following substances would have the lowest boiling point?

Accepted Answer

Methane ($$\mathrm{CH_4$})$$

Chapter 11 Student Notes

Guida di studio - Domande di pratica

Study guide - Flashcard