Question 1

Which of the following substances would you expect to have the highest boiling point, and why?

A. $$\mathrm{CH_4$}
B$$. $$\mathrm{H_2O}
C$$. $$\mathrm{CO_2$}
D$$. $$\mathrm{O_2$}$$

Consider the types of intermolecular forces present in each.

Accepted Answer

$$\mathrm{H_2O}$$, because it forms hydrogen bonds.

Question 2

Which of the following best describes London Dispersion Forces?

Accepted Answer

They arise from temporary fluctuations in electron distribution, present in all molecules.

Question 3

A solution is prepared by dissolving 36 g of $$\mathrm{NaCl} in 100 g of $$water at $$25^\circ\mathrm{C}. $$The solubility of $$\mathrm{NaCl} at $$this temperature is 36 g per 100 g water. Which term best describes this solution?

Accepted Answer

Saturated

Question 4

Which of the following statements about vapor pressure is correct?

Accepted Answer

Vapor pressure increases as temperature increases.

Question 5

Which of the following best explains why ionic solids dissolve in water?

Accepted Answer

The ions are attracted to the partial charges on water molecules, overcoming lattice energy.

Question 6

A phase diagram for a substance shows a triple point at $$0.01^\circ\mathrm{C}$$ and $$0.006$$ atm. What does the triple point represent?

Accepted Answer

The unique temperature and pressure where solid, liquid, and gas phases coexist in equilibrium.

Question 7

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

Accepted Answer

Adding a nonvolatile solute.

Question 8

A sample of water at $$25^\circ\mathrm{C}$$ has a vapor pressure of $$23.8$$ mmHg. If the temperature is increased to $$50^\circ\mathrm{C}$$, what happens to the vapor pressure and why?

Accepted Answer

Vapor pressure increases because more molecules have enough energy to escape into the vapor phase.

Question 9

Which of the following best describes the structure of a metallic solid?

Accepted Answer

A lattice of positive ions surrounded by a sea of delocalized electrons.

Question 10

Which of the following is true about the solubility of gases in water as temperature increases?

Accepted Answer

Solubility decreases because gas molecules escape more easily from the solution.

Question 11

A student is given a white crystalline solid and told it is either sodium chloride ($$\mathrm{NaCl}) or $$sucrose ($$\mathrm{C$$_{12}$$H_{22}O$$_{11}}$). Which test would best distinguish between the two?

Accepted Answer

Test electrical conductivity of an aqueous solution; only $$\mathrm{NaCl}$$ solution will conduct electricity.

Question 12

Which of the following best explains why oil and water do not mix?

Accepted Answer

Oil is nonpolar and cannot form hydrogen bonds with water.

Question 13

Which of the following statements about phase changes is correct?

Accepted Answer

Condensation releases heat to the surroundings.

Question 14

A solution is prepared by mixing 50 mL of ethanol and 50 mL of water. Which intermolecular force is primarily responsible for the miscibility of these two liquids?

Accepted Answer

Hydrogen bonding

Question 15

Which of the following best describes the relationship between boiling point and atmospheric pressure?

Accepted Answer

Boiling point decreases as atmospheric pressure decreases.

Question 16

Which of the following is the correct formula for calculating the vapor pressure of a solution using Raoult's Law?

Accepted Answer

$$P_{solution} = X_{solvent} \cdot P^0$_{solvent}$$

Question 17

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more solute than it can normally hold at a given temperature.

Question 18

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

Accepted Answer

It is the highest temperature at which a liquid can exist.

Question 19

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

Accepted Answer

Ice is less dense than liquid water because its molecules are arranged in an open hexagonal structure.

Question 20

Which of the following is a property of network covalent solids such as diamond?

Accepted Answer

They have high melting points due to strong covalent bonds throughout the structure.

Intermolecular Forces, Properties of Liquids, Phase Changes, Solids, and Solubility: Study Guide

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