Question 1

Which of the following best explains why gases are compressible, while solids and liquids are not?

Accepted Answer

Gas particles are much farther apart, allowing them to be squeezed closer together.

Question 2

Which of the following phase changes requires an increase in both temperature and kinetic energy of the particles?

Accepted Answer

Melting

Question 3

A sample of water is heated from 10°C to 110°C at 1 atm. Which phase changes will occur during this process?

Accepted Answer

Only boiling

Question 4

Which of the following substances would you expect to have the highest boiling point, based on intermolecular forces?

Accepted Answer

CH_3OH

Question 5

Which of the following statements about hydrogen bonding is correct?

Accepted Answer

Hydrogen bonds are especially strong dipole–dipole attractions involving H bonded to N, O, or F.

Question 6

Why does n-pentane have a higher boiling point than neopentane, even though they have the same molar mass?

Accepted Answer

n-Pentane has more surface-to-surface contact, leading to stronger dispersion forces.

Question 7

Which of the following best describes the effect of increasing temperature on the vapor pressure of a liquid?

Accepted Answer

Vapor pressure increases as temperature increases.

Question 8

A liquid forms a concave meniscus in a glass tube. What does this indicate about the relative strengths of adhesive and cohesive forces?

Accepted Answer

Adhesive forces are stronger than cohesive forces.

Question 9

Which of the following best explains why water is a liquid at room temperature, while methane (CH_4) is a gas, even though their molar masses are similar?

Accepted Answer

Water forms hydrogen bonds, which are much stronger than the dispersion forces in methane.

Question 10

Which of the following is true about the process of sublimation?

Accepted Answer

It is the transition from solid directly to gas.

Question 11

Which intermolecular force is present in all substances, regardless of their polarity?

Accepted Answer

Dispersion (London) forces

Question 12

A solution is prepared by dissolving NaCl in water. Which type of intermolecular force is primarily responsible for the solubility of NaCl in water?

Accepted Answer

Ion–dipole forces

Question 13

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

Accepted Answer

A liquid with strong hydrogen bonding

Question 14

Which of the following statements about phase diagrams is correct?

Accepted Answer

The triple point is where all three phases coexist in equilibrium.

Question 15

Which of the following best describes why pentane (C_5H_{12}) and water (H_2O) are immiscible?

Accepted Answer

Water molecules are more strongly attracted to each other than to pentane molecules.

Question 16

Which of the following factors increases the strength of dispersion forces in a molecule?

Accepted Answer

Larger molar mass and greater surface area

Question 17

Which of the following best explains why the boiling point of I_2 is higher than that of Cl_2?

Accepted Answer

I_2 has a larger molar mass, leading to stronger dispersion forces.

Question 18

Which of the following is a property of crystalline solids but not amorphous solids?

Accepted Answer

Long-range ordered structure

Question 19

Which of the following best describes the relationship between intermolecular forces and viscosity?

Accepted Answer

Stronger intermolecular forces result in higher viscosity.

Question 20

A sample of a substance is heated at constant pressure. The temperature increases until it reaches a plateau, then remains constant for a period before rising again. What is happening during the plateau?

Accepted Answer

A phase change is occurring, and energy is being used to overcome intermolecular forces.

Liquids, Solids, and Intermolecular Forces: Study Guide

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