Q: What is the mass percent formula for a solution?

$$\text{Mass percent} = \frac{\text{mass of solute}}{\text{mass of solution}} \times 100$$

Q: A solution is prepared by dissolving 15.5 g NaCl in water to make 1.50 L of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

$$\text{Molarity} = \frac{15.5/58.44}{1.50} = 0.177\,\text{M}$$

Q: A 1.7 m solution of ethylene glycol in water is prepared. If $$K_f$$ for water is 1.86 $$^\circC kg/$$mol, what is the freezing point of the solution?

$$0.00^\circ\text{C} - (1.7 \times 1.86)$$

Q: What is the correct formula for molality?

$$m = \frac{\text{moles of solute}}{\text{mass of solvent (in kg)}}$$

Question 1

Which of the following best describes a solution?

Accepted Answer

A homogeneous mixture of two or more substances.

Question 2

In the Lake Nyos tragedy, why did carbon dioxide suddenly escape from the lake and cause mass fatalities?

Accepted Answer

The drop in pressure as the carbon dioxide-rich water rose caused the gas to come out of solution.

Question 3

Which statement about solubility is correct?

Accepted Answer

The solubility of gases in water increases with increasing pressure.

Question 4

What is the mass percent formula for a solution?

Accepted Answer

$$	ext{Mass percent} = \frac{	ext{mass of solute}}{	ext{mass of solution}} 	imes 100$$

Question 5

A solution is prepared by dissolving 15.5 g NaCl in water to make 1.50 L of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$	ext{Molarity} = \frac{15.5/58.44}{1.50} = 0.177\,	ext{M}$$

Question 6

Which of the following is an example of an electrolyte solution?

Accepted Answer

A solution of sodium chloride (NaCl) in water.

Question 7

What is the effect of adding a nonvolatile solute to water on its freezing and boiling points?

Accepted Answer

Freezing point decreases and boiling point increases.

Question 8

Which equation is used to calculate freezing point depression?

Accepted Answer

$$\Delta T_f = m \cdot K_f$$

Question 9

A 1.7 m solution of ethylene glycol in water is prepared. If $$K_f$$ for water is 1.86 $$^\circC kg/$$mol, what is the freezing point of the solution?

Accepted Answer

$$0.00^\circ	ext{C} - (1.7 	imes 1.86)$$

Question 10

Which property is NOT a colligative property?

Accepted Answer

Color of the solution

Question 11

What is the correct formula for molality?

Accepted Answer

$$m = \frac{	ext{moles of solute}}{	ext{mass of solvent (in kg)}}$$

Question 12

Which statement best explains why salt is used to melt ice on roads in winter?

Accepted Answer

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

Question 13

Which equation is used to calculate boiling point elevation?

Accepted Answer

$$\Delta T_b = m \cdot K_b$$

Question 14

A solution is prepared by mixing 0.9 g NaCl in 100 mL of water. What type of solution is this, and why is it important in medicine?

Accepted Answer

Isoosmotic; it matches the osmotic pressure of bodily fluids.

Question 15

Which statement about osmosis is correct?

Accepted Answer

Osmosis is the flow of solvent from a low-concentration solution to a high-concentration solution.

Question 16

Which equation is used for solution dilution calculations?

Accepted Answer

$$M_1V_1 = M_2V_2$$

Question 17

A chemist needs to prepare 5.00 L of a 1.50 M KCl solution from a 12.0 M stock solution. What volume of stock solution should be used?

Accepted Answer

$$V_1$$ = \frac{1.50 	imes 5.00}{12.0} = 0.625\,	ext{L}$$

Question 18

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

Accepted Answer

The solubility of carbon dioxide in water decreases with temperature.

Chapter 13: Solutions – Structure, Properties, and Applications

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