Question 1

Which of the following best explains why making chemical bonds releases heat to the surroundings?

Accepted Answer

Bond formation results in a more stable, lower-energy state, and the excess energy is released as heat.

Question 2

A sample of water is heated from $$-10\ ^\circ\mathrm{C} to$$ $$110\ ^\circ\mathrm{C}. $$Which of the following steps requires the most energy per mole?

Accepted Answer

Vaporizing water at $$100\ ^\circ\mathrm{C}$$

Question 3

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

Accepted Answer

H$$_2O ($$water)

Question 4

Which equation correctly describes the heat required to raise the temperature of a substance within a single phase?

Accepted Answer

$$q = mC_p\Delta T$$

Question 5

A solution is prepared by dissolving NaCl in water. Which of the following best describes the process?

Accepted Answer

NaCl dissociates into Na$$^+$$ and Cl$$^-$$ ions, which are solvated by water molecules.

Question 6

Which of the following statements about vapor pressure is correct?

Accepted Answer

Vapor pressure increases as temperature increases.

Question 7

A beaker contains a saturated solution of sugar at $$25\ ^\circ\mathrm{C}. $$What will happen if the temperature is decreased to $$10\ ^\circ\mathrm{C}$$?

Accepted Answer

Sugar will precipitate out of solution.

Question 8

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

Accepted Answer

The vapor pressure of the solution decreases.

Question 9

Which formula correctly expresses Raoult’s Law for the vapor pressure of a solution?

Accepted Answer

$$P_{solution} = X_{solvent} P^\circ_{solvent}$$

Question 10

A solution is prepared by dissolving 1 mol of NaCl in 1 kg of water. What is the van’t Hoff factor $$i$$ for this solution, assuming complete dissociation?

Accepted Answer

$$i = 2$$

Question 11

Which of the following best explains why the solubility of gases in water decreases as temperature increases?

Accepted Answer

Gas molecules have higher kinetic energy and escape more easily from the solution.

Question 12

Which of the following is a colligative property?

Accepted Answer

Boiling point elevation

Question 13

A solution is prepared by mixing 0.1 mol of glucose (a non-electrolyte) and 0.1 mol of NaCl in 1 kg of water. What is the total number of moles of particles in solution, assuming complete dissociation of NaCl?

Accepted Answer

0.3 mol

Question 14

Which of the following best describes a supercritical fluid?

Accepted Answer

A fluid that behaves like a gas but is as dense as a liquid.

Question 15

Which of the following equations correctly describes the freezing point depression of a solution?

Accepted Answer

$$\Delta T_f = -i K_f m$$

Question 16

A sample of dry ice (solid CO$$_2) $$sublimes at atmospheric pressure and room temperature. What happens to the temperature of the surroundings?

Accepted Answer

The temperature of the surroundings decreases.

Question 17

Which of the following best explains why water has a much higher surface tension than most other liquids?

Accepted Answer

Water molecules have strong hydrogen bonding between them.

Question 18

Which of the following statements about ideal solutions is correct?

Accepted Answer

Ideal solutions obey Raoult’s Law.

Question 19

Which of the following best describes the process of osmosis?

Accepted Answer

Solvent moves from low solute concentration to high solute concentration through a semipermeable membrane.

Question 20

Which of the following equations correctly expresses Henry’s Law for the solubility of a gas in a liquid?

Accepted Answer

$$S_g = k_H P_g$$

Properties of Liquids, Intermolecular Forces, and Phase Changes

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