Q: A water sample contains 8.5% carbon dioxide by mass. If you have 28.6 L of this solution (density = 1.03 g/mL), how many grams of CO$$_2$$ are present? (Show the correct calculation setup.)

$$28.6\ \text{L} \times \frac{1000\ \text{mL}}{1\ \text{L}} \times \frac{1.03\ \text{g}}{1\ \text{mL}} \times \frac{8.5\ \text{g CO}_2}{100\ \text{g solution}}$$

Q: What is the molarity of a solution made by dissolving 15.5 g NaCl (molar mass = 58.44 g/mol) in enough water to make 1.50 L of solution?

$$\frac{15.5\ \text{g}}{58.44\ \text{g/mol}} = 0.265\ \text{mol};\ \frac{0.265\ \text{mol}}{1.50\ \text{L}} = 0.177\ \text{M}$$

Q: How many grams of sucrose (C$$_{12}H$_{22}O$_{11}$$, molar mass = 342.34 g/mol) are in 1.72 L of a 0.758 M solution?

$$1.72\ \text{L} \times 0.758\ \text{mol/L} \times 342.34\ \text{g/mol} = 446\ \text{g}$$

Question 1

Which of the following best describes why the sudden release of carbon dioxide from Lake Nyos was so deadly?

Accepted Answer

The carbon dioxide was heavier than air and displaced oxygen near the ground, causing suffocation.

Question 2

Which of the following statements about solutions is TRUE?

Accepted Answer

A solution is a homogeneous mixture of two or more substances.

Question 3

Which of the following best explains why NaCl dissolves in water?

Accepted Answer

The solvent–solute attractions between water molecules and NaCl ions overcome the solute–solute and solvent–solvent attractions.

Question 4

A solution contains 36 g of NaCl dissolved in 100 g of water at 25°C. What type of solution is this?

Accepted Answer

Saturated

Question 5

Which of the following compounds would you expect to be insoluble in water?

Accepted Answer

CaCO$$_3 ($$calcium carbonate)

Question 6

Which of the following best describes an electrolyte solution?

Accepted Answer

A solution that contains dissolved ions and conducts electricity.

Question 7

The solubility of gases in water generally:

Accepted Answer

Decreases with increasing temperature and increases with increasing pressure.

Question 8

A water sample contains 8.5% carbon dioxide by mass. If you have 28.6 L of this solution (density = 1.03 g/mL), how many grams of CO$$_2$$ are present? (Show the correct calculation setup.)

Accepted Answer

$$28.6\ 	ext{L} 	imes \frac{1000\ 	ext{mL}}{1\ 	ext{L}} 	imes \frac{1.03\ 	ext{g}}{1\ 	ext{mL}} 	imes \frac{8.5\ 	ext{g CO}_2}{100\ 	ext{g solution}}$$

Question 9

What is the molarity of a solution made by dissolving 15.5 g NaCl (molar mass = 58.44 g/mol) in enough water to make 1.50 L of solution?

Accepted Answer

$$\frac{15.5\ 	ext{g}}{58.44\ 	ext{g/mol}} = 0.265\ 	ext{mol};\ \frac{0.265\ 	ext{mol}}{1.50\ 	ext{L}} = 0.177\ 	ext{M}$$

Question 10

How many grams of sucrose (C$$_{12}H$_{22}O$_{11}$$, molar mass = 342.34 g/mol) are in 1.72 L of a 0.758 M solution?

Accepted Answer

$$1.72\ 	ext{L} 	imes 0.758\ 	ext{mol/L} 	imes 342.34\ 	ext{g/mol} = 446\ 	ext{g}$$

Question 11

A 1.0 M CaCl$$_2$$ solution is prepared. What are the approximate concentrations of Ca$$^{2+}$$ and Cl$$^{-}$$ ions in the solution?

Accepted Answer

1.0 M Ca$$^{2+}$$, 2.0 M Cl$$^{-}$$

Question 12

How much 12.0 M KCl stock solution is needed to prepare 5.00 L of a 1.50 M KCl solution?

Accepted Answer

$$M_1V_1 = M_2V_2;\ V_1$ = \frac{M_2V_2}{M_1$} = \frac{1.50\ 	ext{M} 	imes 5.00\ 	ext{L}}{12.0\ 	ext{M}} = 0.625\ 	ext{L}$$

Question 13

Which equation would you use to calculate the new concentration after diluting a solution?

Accepted Answer

$$M_1V_1 = M_2V_2$$

Question 14

A solution is made by dissolving 17.2 g of ethylene glycol (C$$_2H$_6O$_2$$, molar mass = 62.07 g/mol) in 0.500 kg of water. What is the molality of the solution?

Accepted Answer

$$\frac{17.2\ 	ext{g}}{62.07\ 	ext{g/mol}} = 0.277\ 	ext{mol};\ \frac{0.277\ 	ext{mol}}{0.500\ 	ext{kg}} = 0.554\ 	ext{m}$$

Question 15

Calculate the freezing point of a 1.7 m ethylene glycol solution in water. ($$K_f$$ for water = 1.86 °C kg/mol, freezing point of pure water = 0.00 °C)

Accepted Answer

$$\Delta T_f = m 	imes K_f = 1.7 	imes 1.86 = 3.16\ ^\circ	ext{C};\ 0.00 - 3.16 = -3.16\ ^\circ	ext{C}$$

Question 16

Which of the following is a colligative property?

Accepted Answer

Freezing point depression

Question 17

What is osmosis?

Accepted Answer

The flow of solvent from a low-concentration solution to a high-concentration solution through a semipermeable membrane.

Question 18

Why must intravenous (IV) solutions be isoosmotic with bodily fluids?

Accepted Answer

To prevent water from moving into or out of cells, avoiding cell damage.

Chapter 13: Solutions – Introductory Chemistry Study Notes

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