Question 1

Which of the following best explains why water has a much higher boiling point than expected based on its molar mass?

Accepted Answer

Water molecules form strong hydrogen bonds with each other.

Question 2

Which property is most responsible for the ability of a liquid to rise in a narrow tube (capillary action)?

Accepted Answer

Adhesive forces between the liquid and the tube

Question 3

A sample of ethanol is placed in a closed container. Over time, the rate of evaporation equals the rate of condensation. What is this state called?

Accepted Answer

Dynamic equilibrium

Question 4

Which of the following statements about vapor pressure is correct?

Accepted Answer

Vapor pressure increases as temperature increases.

Question 5

Which equation best describes the relationship between vapor pressure and temperature?

Accepted Answer

$$\ln P = -\frac{\Delta H_{vap}}{R} \left( \frac{1}{T} \right) + C$$

Question 6

Which of the following liquids would you expect to have the highest viscosity at room temperature?

Accepted Answer

Glycerol, due to its extensive hydrogen bonding

Question 7

A liquid with strong intermolecular forces will generally have which of the following properties?

Accepted Answer

High boiling point and low vapor pressure

Question 8

Which of the following best describes the process of sublimation?

Accepted Answer

A solid changes directly into a gas without passing through the liquid phase.

Question 9

Which of the following is NOT a characteristic of crystalline solids?

Accepted Answer

They have a random arrangement of particles.

Question 10

Which of the following best explains why salt (NaCl) is used to melt ice on roads in winter?

Accepted Answer

Salt lowers the freezing point of water, causing ice to melt at lower temperatures.

Question 11

Which of the following statements about phase diagrams is correct?

Accepted Answer

The triple point is where solid, liquid, and gas phases coexist in equilibrium.

Question 12

A sample of water is heated from 20 $$^\circC to 120$$ $$^\circC at 1 $$atm. At what temperature does the phase change from liquid to gas occur?

Accepted Answer

$$100\ ^\circ\mathrm{C}$$

Question 13

Which of the following best describes the difference between evaporation and boiling?

Accepted Answer

Evaporation occurs at the surface at all temperatures; boiling occurs throughout the liquid at a specific temperature.

Question 14

Which of the following is a correct statement about the enthalpy of fusion ($$\Delta H_{fus}$$)?

Accepted Answer

$$\Delta H_{fus} is $$the energy required to convert a solid to a liquid at its melting point.

Question 15

Which of the following best explains why sweating cools the human body?

Accepted Answer

Evaporation of sweat absorbs heat from the skin due to the enthalpy of vaporization.

Question 16

Which of the following would increase the rate of evaporation of a liquid?

Accepted Answer

Increasing the temperature of the liquid

Question 17

A liquid boils when its vapor pressure equals which of the following?

Accepted Answer

The external atmospheric pressure

Question 18

Which of the following best describes why mercury forms a convex meniscus in a glass tube?

Accepted Answer

Cohesive forces between mercury atoms are stronger than adhesive forces to glass.

Question 19

Which of the following is true about the critical point on a phase diagram?

Accepted Answer

Above the critical temperature and pressure, the liquid and gas phases are indistinguishable.

Question 20

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water due to its open hexagonal structure.

Intermolecular Forces and Properties of Liquids (Based on Chapter 11 Objectives)

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