Question 1

Which of the following best explains why gases are easily compressed compared to liquids and solids?

Accepted Answer

Gases have relatively weak intermolecular forces.

Question 2

At 298 K and 1 atm, H$_2$O is a liquid with a high vapor pressure, and CO$_2$ is a gas. What does this indicate about the intermolecular forces in these substances?

Accepted Answer

H$_2$O has stronger intermolecular forces than CO$_2$.

Question 3

Which of the following molecules would have the highest boiling point, and why?

Accepted Answer

NH$_3$, because it can form hydrogen bonds.

Question 4

Which of the following statements about the phase diagram of water is correct?

Accepted Answer

The solid-liquid equilibrium line has a negative slope.

Question 5

Which of the following processes results in a decrease in entropy ($\Delta S$) of a system?

Accepted Answer

Water is frozen into ice.

Question 6

A sample of ice at $-10\ ^\circ\mathrm{C}$ is placed in a warm room. Which of the following best describes the energy changes as the ice melts and then warms to room temperature?

Accepted Answer

Energy is absorbed to break hydrogen bonds and increase molecular motion.

Question 7

Which of the following molecules is most soluble in water?

Accepted Answer

Methanol (CH$_3$OH)

Question 8

Which of the following best describes why the enthalpy of vaporization of HF is greater than that of HCl?

Accepted Answer

HF forms stronger hydrogen bonds than HCl.

Question 9

Which of the following is the best explanation for why the radius of an Al atom is larger than the radius of an Al$^{3+}$ ion?

Accepted Answer

Al$^{3+}$ has lost electrons, resulting in less electron-electron repulsion.

Question 10

Which of the following is NOT a type of intermolecular force present in pure samples of HF?

Accepted Answer

Ionic bonding

Question 11

Which of the following best describes the energy changes when a solute is added to hot water in a rigid, insulated container?

Accepted Answer

Energy remains constant; entropy increases.

Question 12

Which of the following best explains why the cis-isomer of 1,2-dichloroethene has a lower equilibrium vapor pressure than the trans-isomer at 20$^	ext{o}$C?

Accepted Answer

The cis-isomer has a net dipole moment, leading to stronger intermolecular forces.

Question 13

A 4.00 g sample of CaCl$_2$ undergoes the phase transition illustrated in the diagram below. If the enthalpy of vaporization, $\Delta H_{vap}$, is $54.0\ \mathrm{kJ/mol}$, what is the energy absorbed during this process? (Molar mass of CaCl$_2$ = 111 g/mol)

Accepted Answer

$1.95\ \mathrm{kJ}$

Question 14

Which of the following best describes the effect of increasing temperature on the solubility of most solids in water?

Accepted Answer

Solubility increases as temperature increases.

Question 15

Which of the following best explains why water has a higher boiling point than hydrogen sulfide (H$_2$S)?

Accepted Answer

Water forms hydrogen bonds, which are stronger than the dipole-dipole forces in H$_2$S.

Question 16

Which of the following is the best explanation for why the vapor pressure of a liquid increases with temperature?

Accepted Answer

More molecules have enough kinetic energy to escape the liquid phase.

Question 17

Which of the following best describes the effect of adding a nonvolatile solute to a solvent?

Accepted Answer

The vapor pressure of the solvent decreases.

Question 18

Which of the following best describes the process of sublimation?

Accepted Answer

A solid changes directly to a gas.

Question 19

Which of the following best explains why ionic compounds tend to have high melting points?

Accepted Answer

Strong electrostatic forces hold the ions together.

Question 20

Which of the following best describes the energy changes when a liquid vaporizes at its boiling point?

Accepted Answer

Energy is absorbed to overcome intermolecular forces.

Unit 4 Study Guide: Intermolecular Forces, Liquids & Solids, Thermochemistry, and Atomic Structure

Study Guide - Practice Questions

Study Guide - Flashcards