Q: What is the correct formula for calculating mass percent of a solute in a solution?

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

Q: Which solution will conduct electricity?

A solution of sodium chloride ($$\text{NaCl}) in $$water

Question 1

Which of the following best explains why carbon dioxide was able to build up at the bottom of Lake Nyos, leading to the 1986 tragedy?

Accepted Answer

The solubility of carbon dioxide in water increases with increasing pressure.

Question 2

Which statement correctly describes a solution?

Accepted Answer

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

Question 3

What is the correct formula for calculating mass percent of a solute in a solution?

Accepted Answer

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

Question 4

A water sample from Lake Nyos contains 8.5% CO$$_2 by $$mass and has a density of 1.03 g/mL. How many grams of CO$$_2$$ are in 28.6 L of this solution?

Accepted Answer

$$2.5 	imes 10^3$ g CO_2$

Question 5

Which of the following is a common polar solvent used in laboratory settings?

Accepted Answer

Water ($$	ext{H}_2	ext{O})$$

Question 6

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

Accepted Answer

Water molecules surround Na$$^+$$ and Cl$$^-$$ ions, dispersing them in solution.

Question 7

Which solution will conduct electricity?

Accepted Answer

A solution of sodium chloride ($$	ext{NaCl}) in $$water

Question 8

How does the solubility of a gas in water change with temperature?

Accepted Answer

Solubility decreases with increasing temperature.

Question 9

According to Henry’s Law, what happens to the solubility of a gas in a liquid as the pressure of the gas above the liquid increases?

Accepted Answer

The solubility increases.

Question 10

Calculate the molarity of a solution made by dissolving 15.5 g NaCl in enough water to make 1.50 L of solution. (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$0.177 M$$

Question 11

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

Accepted Answer

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

Question 12

How much 0.125 M NaOH solution is needed to completely neutralize 0.225 L of 0.175 M H$$_2SO$_4$$ solution? (Balanced equation: $$	ext{H}_2	ext{SO}_4 + 2	ext{NaOH} ightarrow 2	ext{H}_2	ext{O} + 	ext{Na}_2	ext{SO}_4)$$

Accepted Answer

$$0.630 L$$

Question 13

What is the effect of adding a nonvolatile solute to a liquid in terms of colligative properties?

Accepted Answer

It lowers the freezing point and raises the boiling point.

Question 14

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

Accepted Answer

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

Question 15

A 1.7 m ethylene glycol solution is prepared. What is its boiling point? ($$K_b = 0.512\ ^\circ	ext{C}\ 	ext{kg solvent}/	ext{mol solute}$$, boiling point of pure water = $$100.00\ ^\circ	ext{C})$$

Accepted Answer

$$100.87\ ^\circ	ext{C}$$

Question 16

Why do wood frogs survive freezing temperatures in winter?

Accepted Answer

Their cells contain a high concentration of glucose that acts as antifreeze.

Question 17

What happens to a red blood cell placed in pure water?

Accepted Answer

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

Question 18

Why is it dangerous to drink seawater?

Accepted Answer

Seawater draws water out of bodily tissues by osmosis, causing dehydration.

Chapter 13: Solutions – Properties, Preparation, and Applications

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