Question 1

Which of the following best explains why NaCl(s) dissolves readily in water, even though the ionic bonds in NaCl are very strong?

Accepted Answer

The ion-dipole interactions between Na+ and Cl- ions and water molecules are stronger than the ionic bonds in NaCl.

Question 2

A solution is prepared by dissolving 2.0 mol of KNO3 in enough water to make 1.0 L of solution. The density of the solution is 1.107 g/cm$^3$. The formula weight of KNO3 is 101.10 g/mol. Is this solution unsaturated, saturated, or supersaturated at 25°C, given that the solubility of KNO3 at this temperature is 35 g per 100 g H2O?

Accepted Answer

Unsaturated

Question 3

Which of the following compounds will NOT conduct electricity when dissolved in water?

Accepted Answer

C$_6$H$_{12}$O$_6$

Question 4

Which of the following best describes the process occurring at the triple point in a phase diagram?

Accepted Answer

All three phases (solid, liquid, gas) are in equilibrium.

Question 5

Which of the following statements about entropy and solution formation is correct?

Accepted Answer

Entropy increases when a solution forms because there are more ways to arrange the particles.

Question 6

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

Accepted Answer

Oil is nonpolar and water is polar, so their intermolecular forces are not compatible.

Question 7

Which of the following is a strong electrolyte?

Accepted Answer

NaOH

Question 8

A sealed container contains oxygen gas above water. If the external pressure is increased, what happens to the solubility of oxygen in water?

Accepted Answer

The solubility increases.

Question 9

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more solute than the solubility limit under current conditions.

Question 10

Which of the following is the correct dissolution reaction for Pb(NO$_3$)$_2$(s) in water?

Accepted Answer

$\mathrm{Pb(NO_3)_2(s) \rightarrow Pb^{2+}(aq) + 2\ NO_3^-(aq)}$

Question 11

Which of the following best describes the effect of increasing temperature on the solubility of a gas in a liquid?

Accepted Answer

Solubility decreases as temperature increases.

Question 12

Which of the following is true about the solution formed when NH$_4$NO$_3$ dissolves in water, given $\Delta H_{rxn} = +25.67\ \mathrm{kJ/mol}$?

Accepted Answer

The solution feels cold because the dissolution is endothermic and entropy drives the process.

Question 13

Which of the following best describes a weak electrolyte?

Accepted Answer

A substance that partially ionizes in solution, producing both ions and neutral molecules.

Question 14

Which of the following is the correct application of Henry’s Law for the solubility of a gas?

Accepted Answer

$C_{gas} = k_H P_{gas}$

Question 15

Which of the following best explains why a solution of ethanol in water is possible, but a solution of methane in water is not?

Accepted Answer

Ethanol and water can both form hydrogen bonds, but methane cannot.

Question 16

Which of the following ions is always associated with a soluble compound, according to the solubility rules?

Accepted Answer

NO$_3^-$

Question 17

Which of the following best describes the process of melting as shown on a phase diagram?

Accepted Answer

A transition from solid to liquid at constant temperature.

Question 18

Which of the following is a nonelectrolyte?

Accepted Answer

C$_6$H$_{12}$O$_6$

Question 19

Which of the following best describes a saturated solution?

Accepted Answer

A solution in which the amount of dissolved solute is equal to the solubility limit, and some solid may be present.

Question 20

Which of the following is the correct dissolution reaction for (NH$_4$)$_3$PO$_4$(s) in water?

Accepted Answer

$(NH_4)_3PO_4(s) \rightarrow 3\ NH_4^+(aq) + PO_4^{3-}(aq)$

Solutions, Dissolution, Electrolytes, and Solubility: Study Notes for General Chemistry

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