Q: A solution contains 0.340 g of ammonia in 2.00 $ \times $ 10^3 mL of water. What is the concentration in parts per million (ppm)? (Assume 1 mL water = 1 g)

$\mathrm{ppm} = \frac{0.340}{2000} \times 10^6 = 170\ \mathrm{ppm}$

Q: According to Henry’s Law, what is the solubility of oxygen in water at 25°C exposed to air at 1.0 atm, if the partial pressure of oxygen is 0.21 atm and $k_H$ for $O_2$ is $1.3 \times 10^{-3}$ M/atm?

$S_{O_2} = 0.21 \times 1.3 \times 10^{-3} = 2.7 \times 10^{-4}\ \mathrm{M}$

Q: A solution is prepared by dissolving 99.5 g of sucrose ($\mathrm{C_{12}H_{22}O_{11}}$, molar mass = 342.3 g/mol) in 300.0 mL of water (density = 1.00 g/mL). What is the mole fraction of sucrose in the solution?

$\chi_{\text{sucrose}} = \frac{99.5/342.3}{99.5/342.3 + 300/18.02} = 0.018$

Question 1

Which of the following best explains why wood frogs can survive freezing temperatures, while most other cold-blooded animals cannot?

Accepted Answer

Wood frogs increase the concentration of glucose in their blood, lowering the freezing point of their body fluids.

Question 2

Which of the following is an example of a solution where the solute and solvent are both gases?

Accepted Answer

Air (mainly oxygen and nitrogen)

Question 3

Which intermolecular force is primarily responsible for the solubility of ionic compounds in water?

Accepted Answer

Ion-dipole interactions

Question 4

A solution is prepared by dissolving 17.2 g of ethylene glycol (C2H6O2, molar mass = 62.07 g/mol) in 0.500 kg of water. What is the molality of the solution?

Accepted Answer

$m = \frac{17.2/62.07}{0.500} = 0.554\ \mathrm{m}$

Question 5

Which of the following statements about the energetics of solution formation is correct?

Accepted Answer

The overall enthalpy change depends on the balance between breaking solute-solute, solvent-solvent, and forming solute-solvent interactions.

Question 6

Which of the following compounds would be most soluble in hexane (a nonpolar solvent)?

Accepted Answer

Propane ($\mathrm{CH_3CH_2CH_3}$)

Question 7

A solution contains 0.340 g of ammonia in 2.00 $ \times $ 10^3 mL of water. What is the concentration in parts per million (ppm)? (Assume 1 mL water = 1 g)

Accepted Answer

$\mathrm{ppm} = \frac{0.340}{2000} 	imes 10^6 = 170\ \mathrm{ppm}$

Question 8

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more solute than the saturation point at a given temperature.

Question 9

According to Henry’s Law, what is the solubility of oxygen in water at 25°C exposed to air at 1.0 atm, if the partial pressure of oxygen is 0.21 atm and $k_H$ for $O_2$ is $1.3 	imes 10^{-3}$ M/atm?

Accepted Answer

$S_{O_2} = 0.21 	imes 1.3 	imes 10^{-3} = 2.7 	imes 10^{-4}\ \mathrm{M}$

Question 10

Which of the following best explains why warm soda fizzes more than cold soda when opened?

Accepted Answer

The solubility of CO$_2$ in water decreases with temperature.

Question 11

A solution is prepared by dissolving 99.5 g of sucrose ($\mathrm{C_{12}H_{22}O_{11}}$, molar mass = 342.3 g/mol) in 300.0 mL of water (density = 1.00 g/mL). What is the mole fraction of sucrose in the solution?

Accepted Answer

$\chi_{	ext{sucrose}} = \frac{99.5/342.3}{99.5/342.3 + 300/18.02} = 0.018$

Question 12

Which equation correctly expresses Raoult’s Law for the vapor pressure of a solvent in a solution?

Accepted Answer

$P_{	ext{solution}} = \chi_{	ext{solvent}} P^\circ_{	ext{solvent}}$

Question 13

A solution contains 0.102 mol Ca(NO$_3$)$_2$ and 0.927 mol H$_2$O. Assuming complete dissociation, what is the mole fraction of water in the solution?

Accepted Answer

$\chi_{	ext{H}_2	ext{O}} = \frac{0.927}{0.927 + 0.306}$

Question 14

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

Accepted Answer

It decreases the vapor pressure of the solvent.

Question 15

Calculate the freezing point of a 2.6-m aqueous sucrose solution. ($K_f$ for water = 1.86 °C/m)

Accepted Answer

$\Delta T_f = 2.6 	imes 1.86 = 4.84\ ^\circ\mathrm{C}$;\ T_f = 0.00 - 4.84 = -4.84\ ^\circ\mathrm{C}$

Question 16

A solution is prepared by dissolving 1.50 g of ethylene glycol (C$_2$H$_6$O$_2$) in 50.0 mL of solution at 25°C. What is the osmotic pressure (in atm)? ($R = 0.08206$ L·atm/mol·K, $T = 298$ K, molar mass = 62.07 g/mol)

Accepted Answer

$\Pi = 0.48\ \mathrm{atm}$

Question 17

Which of the following best describes an isotonic (isosmotic) solution in a medical context?

Accepted Answer

A solution with the same osmotic pressure as the cell, resulting in no net flow of water.

Question 18

A 0.10-m FeCl$_3$ solution has a van’t Hoff factor of 3.2. What is the expected freezing point depression? ($K_f$ for water = 1.86 °C/m)

Accepted Answer

$\Delta T_f = 0.10 	imes 3.2 	imes 1.86 = 0.595\ ^\circ\mathrm{C}$

Chapter 13: Solutions – Structure, Properties, and Colligative Effects

Study Guide - Practice Questions

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