Q: A solution is prepared by dissolving 170.1 g of glucose (molar mass = 180.2 g/mol) in enough water to make 1.00 L of solution. The density of the solution is 1.062 g/mL. What is the molality ($$m) of $$the solution? (Assume the density is used to find the mass of the solution.)

$$m = \frac{0.944\ \text{mol}}{0.892\ \text{kg}} = 1.06\ \text{m}$$

Q: A chemist prepares a solution of KOH that is 7.15% by mass and has a density of 1.080 g/mL. What is the molarity ($$M) of $$the solution? (Molar mass of KOH = 56.11 g/mol)

$$M = \frac{7.15\ \text{g}}{56.11\ \text{g/mol}} \times \frac{1000\ \text{mL}}{1.080\ \text{g/mL} \times 100\ \text{g}} = 1.18\ \text{M}$$

Q: A solution is made by dissolving a nonvolatile solute in ethanol. If the vapor pressure of pure ethanol at 20°C is 44.6 mmHg and the mole fraction of ethanol in the solution is 0.954, what is the vapor pressure of the solution?

$$P = (0.954)(44.6\ \text{mmHg}) = 42.6\ \text{mmHg}$$

Q: Calculate the boiling point of a solution made by dissolving 685 g of ethylene glycol (molar mass = 62.07 g/mol) in 2075 g of water. ($$K_b$$ for water = 0.52°C/m, boiling point of pure water = 100.0°C)

$$T_b = 100.0^\circ\text{C} + (5.32\ \text{m} \times 0.52^\circ\text{C/m}) = 102.8^\circ\text{C}$$

Q: A soda is bottled with CO$$_2 at 5.0 $$atm at 25°C. The Henry’s law constant for CO$$_2 in $$water at this temperature is $$3.1 \times 10$$^{-2}$$ mol/(L·atm). What is the concentration of CO_2$ before the bottle is opened?

$$C = (3.1 \times 10$$^{-2}$$) \times 5.0 = 0.16\ \text{mol/L}$$

Question 1

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more solute than the maximum amount that can dissolve at a given temperature.

Question 2

Which of the following pairs will be miscible according to the 'like dissolves like' rule?

Accepted Answer

Acetone (polar) and water (polar)

Question 3

The solubility of a gas in water will ______ as the temperature increases and ______ as the pressure above the solution increases.

Accepted Answer

decrease; increase

Question 4

A solution is prepared by dissolving 170.1 g of glucose (molar mass = 180.2 g/mol) in enough water to make 1.00 L of solution. The density of the solution is 1.062 g/mL. What is the molality ($$m) of $$the solution? (Assume the density is used to find the mass of the solution.)

Accepted Answer

$$m = \frac{0.944\ 	ext{mol}}{0.892\ 	ext{kg}} = 1.06\ 	ext{m}$$

Question 5

Which of the following statements about colligative properties is TRUE?

Accepted Answer

They depend only on the number of solute particles present.

Question 6

A chemist prepares a solution of KOH that is 7.15% by mass and has a density of 1.080 g/mL. What is the molarity ($$M) of $$the solution? (Molar mass of KOH = 56.11 g/mol)

Accepted Answer

$$M = \frac{7.15\ 	ext{g}}{56.11\ 	ext{g/mol}} 	imes \frac{1000\ 	ext{mL}}{1.080\ 	ext{g/mL} 	imes 100\ 	ext{g}} = 1.18\ 	ext{M}$$

Question 7

Which equation correctly expresses Henry’s Law for the solubility of a gas?

Accepted Answer

$$C = kP$$

Question 8

A solution is made by dissolving a nonvolatile solute in ethanol. If the vapor pressure of pure ethanol at 20°C is 44.6 mmHg and the mole fraction of ethanol in the solution is 0.954, what is the vapor pressure of the solution?

Accepted Answer

$$P = (0.954)(44.6\ 	ext{mmHg}) = 42.6\ 	ext{mmHg}$$

Question 9

Which of the following will have the greatest effect on lowering the freezing point of water? (Assume ideal van’t Hoff factors.)

Accepted Answer

0.04 m AlCl$$_3 (i = 4)$$

Question 10

Calculate the boiling point of a solution made by dissolving 685 g of ethylene glycol (molar mass = 62.07 g/mol) in 2075 g of water. ($$K_b$$ for water = 0.52°C/m, boiling point of pure water = 100.0°C)

Accepted Answer

$$T_b = 100.0^\circ	ext{C} + (5.32\ 	ext{m} 	imes 0.52^\circ	ext{C/m}) = 102.8^\circ	ext{C}$$

Question 11

Which of the following best explains why salt is spread on icy roads in winter?

Accepted Answer

Salt decreases the freezing point of water, causing ice to melt at lower temperatures.

Question 12

Which formula is used to calculate the osmotic pressure ($$\pi) of a $$solution?

Accepted Answer

$$\pi = MRT$$

Question 13

A red blood cell is placed in a hypotonic solution. What will happen to the cell?

Accepted Answer

It will swell and may burst due to water entering the cell.

Question 14

Which of the following is NOT a colligative property?

Accepted Answer

Molarity

Question 15

If a solution is prepared by dissolving NaCl in water, which equation should be used to calculate the freezing point depression, considering NaCl is an electrolyte?

Accepted Answer

$$\Delta T_f = imK_f$$

Question 16

A soda is bottled with CO$$_2 at 5.0 $$atm at 25°C. The Henry’s law constant for CO$$_2 in $$water at this temperature is $$3.1 	imes 10$$^{-2}$$ mol/(L·atm). What is the concentration of CO_2$ before the bottle is opened?

Accepted Answer

$$C = (3.1 	imes 10$$^{-2}$$) 	imes 5.0 = 0.16\ 	ext{mol/L}$$

Question 17

Which of the following best describes the process of osmosis?

Accepted Answer

The movement of solvent molecules from low to high solute concentration through a semipermeable membrane.

Physical Properties of Solutions – General Chemistry Chapter 13 Study Notes

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