Q: Which of the following is a correct expression for mass percent?

$$\text{mass percent} = \frac{\text{mass solute}}{\text{mass solute} + \text{mass solvent}} \times 100\%$$

Question 1

Which of the following best explains why carbon dioxide was able to accumulate in high concentrations at the bottom of Lake Nyos?

Accepted Answer

The high pressure at the lake bottom increased the solubility of CO$$_2.$$

Question 2

Which of the following is the correct definition of a solution in chemistry?

Accepted Answer

A homogeneous mixture of two or more substances.

Question 3

Which statement best describes the process of dissolving NaCl in water?

Accepted Answer

The positive ends of water dipoles are attracted to Cl$$^-$$ ions, and the negative ends are attracted to Na$$^+$$ ions.

Question 4

A solution is prepared by dissolving 15.5 g of NaCl in enough 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

$$0.177\ \mathrm{M}$$

Question 5

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

Accepted Answer

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

Question 6

Which of the following is a correct expression for mass percent?

Accepted Answer

$$	ext{mass percent} = \frac{	ext{mass solute}}{	ext{mass solute} + 	ext{mass solvent}} 	imes 100\%$$

Question 7

A 1.50 M solution of Na$$_3PO$_4 is $$prepared. What are the concentrations of Na$$^+$$ and PO$$_4$$^{3-}$$ ions in the solution?

Accepted Answer

Na$$^+$$: 4.50 M, PO$$_4$$^{3-}$$: 1.50 M

Question 8

Which of the following statements about colligative properties is TRUE?

Accepted Answer

They depend only on the number of solute particles.

Question 9

Calculate the freezing point of a 1.7 m ethylene glycol solution in water. ($$K_f$$ for water = $$1.86\ ^\circ\mathrm{C}\ \mathrm{kg}/\mathrm{mol})$$

Accepted Answer

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

Question 10

Which laboratory safety rule must be followed when diluting concentrated acids?

Accepted Answer

Always add acid to water.

Question 11

A solution is made by dissolving 17.2 g of ethylene glycol (C$$_2H$_6O$_2) in 0.500 kg of $$water. What is the molality of the solution? (Molar mass of C$$_2H$_6O$_2 = 62.08 g/$$mol)

Accepted Answer

$$0.554\ m$$

Question 12

Which of the following best describes osmosis as it relates to red blood cells placed in pure water?

Accepted Answer

Water flows into the cell, causing it to swell and possibly burst.

Question 13

Which of the following is the correct equation for solution dilution?

Accepted Answer

$$M_1V_1 = M_2V_2$$

Question 14

A water sample from Lake Nyos contains 8.5% CO$$_2 by $$mass. If you have 28.6 L of this solution (density = 1.03 g/mL), how many grams of CO$$_2$$ are present?

Accepted Answer

$$2.5 	imes 10^3$ g

Question 15

Which of the following best explains why drinking seawater causes dehydration?

Accepted Answer

Osmosis causes water to flow from bodily tissues into the intestine.

Question 16

Which of the following is a real-world example of a supersaturated solution?

Accepted Answer

A can of soda pop immediately after opening.

Question 17

Which of the following best describes why persistent organic pollutants (POPs) are dangerous in the environment?

Accepted Answer

They are nonpolar, accumulate in fatty tissues, and undergo bioamplification.

Question 18

Which of the following is TRUE about electrolyte solutions?

Accepted Answer

They contain dissolved ions and conduct electricity.

Chapter 13: Solutions – Properties, Preparation, and Applications

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