Question 1

Which of the following statements concerning liquids is incorrect?

Accepted Answer

Liquid molecules move slowly compared to solids.

Question 2

When a solid undergoes a phase change to a gas, the process is called:

Accepted Answer

sublimation

Question 3

Which of the following processes must exist in equilibrium with the evaporation process when a measurement of vapor pressure is made?

Accepted Answer

condensation

Question 4

A liquid placed in a closed container will evaporate until equilibrium is reached. At equilibrium, which of the following statements is false?

Accepted Answer

The boundary (meniscus) between liquid and vapor disappears.

Question 5

The normal boiling point of a liquid is:

Accepted Answer

the temperature at which the vapor pressure equals $$760\ \mathrm{mmHg}.$$

Question 6

You are given the following boiling point data: Which one of the liquids would you expect to have the highest vapor pressure at room temperature?

Water, $$H_2O$$ $$100^\circC
$$Methanol, $$CH_3OH$$ $$64.96^\circC
$$Ethanol, $$CH_3CH_2OH$$ $$78.5^\circC
$$Diethyl ether, $$CH_3CH_2OCH_2CH_3$$ $$34.5^\circC
$$Ethylene glycol, $$HOCH_2CH_2OH$$ $$198^\circC$$

Accepted Answer

diethyl ether

Question 7

Which of the following phase changes are exothermic?

Accepted Answer

condensation

Question 8

Assume $$12,500\ \mathrm{J} of $$energy is added to $$2.0$$ moles ($$36$$ grams) of $$H_2O as an $$ice sample at $$0^\circC. $$The molar heat of fusion is $$6.02\ \mathrm{kJ/mol}. $$The specific heat of liquid water is $$4.18\ \mathrm{J/g\ ^\circ C}. $$The molar heat of vaporization is $$40.6\ \mathrm{kJ/mol}. $$The resulting sample contains which of the following?

Accepted Answer

water

Question 9

The vapor pressure of a liquid increases with increasing temperature. Which of the following statements best explains this relationship?

Accepted Answer

The average kinetic energy of molecules is greater; thus more molecules can enter the gaseous state.

Question 10

For a particular liquid, raising its temperature from $$298\ \mathrm{K} to$$ $$318\ \mathrm{K}$$ causes its vapor pressure to double. What is the enthalpy of vaporization of this liquid? ($$R = 8.31\ \mathrm{J/(K\cdot mol)})$$

Accepted Answer

$$27.3\ \mathrm{kJ/mol}$$

Question 11

Choose the correct statement about the phase diagram shown below.

$$	ext{[See first image]}$$

Accepted Answer

The diagram shows that the melting point of the solid increases with increasing pressure.

Question 12

From a consideration of the phase diagram below, a change from point M to point N corresponds to:

$$	ext{[See second image]}$$

Accepted Answer

freezing

Question 13

Below is a phase diagram for a substance. What is the name for point Z on the diagram?

$$	ext{[See third image]}$$

Accepted Answer

critical point

Question 14

Which is the best reason for why water in a glass capillary has a concave meniscus, while mercury in a glass capillary has a convex meniscus?

Accepted Answer

The water is attracted more strongly to the glass than the mercury is attracted to the glass.

Question 15

Which one of the following decreases as the strength of the attractive intermolecular forces increases?

Accepted Answer

The vapor pressure of a liquid.

Question 16

Which of the following compounds has the highest vapor pressure at $$25^\circC$$?

Accepted Answer

$$CH_3CH_2CH_3$$

Question 17

Which of the following pure substances has the highest normal boiling point?

Accepted Answer

$$HF$$

Question 18

Which of the following pure substances has the lowest vapor pressure at $$25^\circC$$?

Accepted Answer

$$H_2O$$

Question 19

Rank the following molecules in order of increasing normal boiling point: $$CH_3CH_2OH$$, $$CH_3CH_2CH_2OH$$, $$CH_3CH_2OCH_3.$$

Accepted Answer

lowest $$CH_3CH_2OCH_3$$, $$CH_3CH_2OH$$, $$CH_3CH_2CH_2OH$$ highest.

Question 20

Which of the following pure substances may exhibit hydrogen bonding?

Accepted Answer

$$H_2NNH_2$$

Phase Diagrams and Properties of Liquids and Solids – Guided Study

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