Q: A sample of water from Lake Nyos contains 8.5% carbon dioxide by mass. If you have 28.6 L of this solution with a density of $$1.03\ \mathrm{g/mL}$$, how many grams of carbon dioxide are present? (Use $$1000\ \mathrm{mL} = 1\ \mathrm{L})$$

$$2.51 \times 10^3$\ \mathrm{g}$$

Question 1

Which of the following best explains why the sudden release of carbon dioxide from Lake Nyos was so deadly to people and animals in the surrounding area?

Accepted Answer

Carbon dioxide is heavier than air and displaced oxygen at ground level, causing asphyxiation in people and animals.

Question 2

Which of the following statements about solutions is correct?

Accepted Answer

A solution is a homogeneous mixture of two or more substances, which can be in any phase.

Question 3

When sodium chloride ($$\mathrm{NaCl}) $$dissolves in water, which of the following best describes the process at the molecular level?

Accepted Answer

Water molecules surround and separate the $$\mathrm{Na^+}$$ and $$\mathrm{Cl^-}$$ ions, dispersing them throughout the solution.

Question 4

Which of the following best describes a saturated solution?

Accepted Answer

A solution that holds the maximum amount of solute under the solution conditions; any additional solute will not dissolve.

Question 5

A sample of water from Lake Nyos contains 8.5% carbon dioxide by mass. If you have 28.6 L of this solution with a density of $$1.03\ \mathrm{g/mL}$$, how many grams of carbon dioxide are present? (Use $$1000\ \mathrm{mL} = 1\ \mathrm{L})$$

Accepted Answer

$$2.51 	imes 10^3$\ \mathrm{g}$$

Question 6

Which of the following statements about the solubility of gases in liquids is correct?

Accepted Answer

The solubility of gases in liquids increases with increasing pressure and decreases with increasing temperature.

Question 7

Which equation correctly expresses the mass percent of a solute in a solution?

Accepted Answer

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

Question 8

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

Accepted Answer

$$0.177\ \mathrm{M}$$

Question 9

Which of the following best describes an electrolyte solution?

Accepted Answer

A solution that contains dissolved ions and conducts electricity.

Question 10

A $$1.0\ \mathrm{M}$$ solution of $$\mathrm{$$CaCl_2$$} is $$prepared. What are the approximate concentrations of $$\mathrm{Ca$$^{2+}$$}$$ and $$\mathrm{Cl^-}$$ ions in the solution?

Accepted Answer

$$1.0\ \mathrm{M}\ \mathrm{Ca$$^{2+}$$}$$ and $$2.0\ \mathrm{M}\ \mathrm{Cl^-}$$

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

A solution is made by dissolving $$17.2\ \mathrm{g} of $$ethylene glycol ($$\mathrm{C_2H_6O_2}$$, molar mass $$62.07\ \mathrm{g/mol}) in$$ $$0.500\ \mathrm{kg} of $$water. What is the molality of the solution?

Accepted Answer

$$0.277\ \mathrm{m}$$

Question 13

Calculate the freezing point of a $$1.7\ \mathrm{m}$$ aqueous ethylene glycol solution. ($$K_f$$ for water $$= 1.85\ ^\circ\mathrm{C}\cdot\mathrm{kg}/\mathrm{mol}$$, freezing point of pure water $$= 0.00\ ^\circ\mathrm{C})$$

Accepted Answer

$$-3.2\ ^\circ\mathrm{C}$$

Question 14

Which of the following is a colligative property?

Accepted Answer

Boiling point elevation

Question 15

A laboratory technician needs to prepare $$5.00\ \mathrm{L} of a$$ $$1.50\ \mathrm{M}$$ KCl solution from a $$12.0\ \mathrm{M}$$ stock solution. What volume of the stock solution is required?

Accepted Answer

$$0.625\ \mathrm{L}$$

Question 16

Which of the following best describes osmosis?

Accepted Answer

The flow of solvent from a less concentrated solution to a more concentrated solution through a semipermeable membrane.

Question 17

A $$0.115\ \mathrm{M} KI $$solution is used to completely precipitate the Pb$$^{2+} in$$ $$0.104\ \mathrm{L} of$$ $$0.225\ \mathrm{M} Pb(NO$_3$$)$$_2$$ solution according to the reaction: $$2\mathrm{KI} + \mathrm{Pb(NO_3$)_2} \rightarrow \mathrm{$$PbI_2$$} + 2\mathrm{$$KNO_3$$}. $$What volume of KI solution is required?

Accepted Answer

$$0.407\ \mathrm{L}$$

Question 18

Which of the following best explains why intravenous (IV) solutions must be isoosmotic with bodily fluids?

Accepted Answer

Isoosmotic solutions prevent water from moving into or out of cells, maintaining cell integrity.

Chapter 13: Solutions – Study Notes for Introductory Chemistry

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