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

$$\frac{10}{10+90} \times 100\% = 10\%$$

$$X_A = \frac{\text{moles of A}}{\text{sum of moles of all components}}$$

$$m = \frac{0.5}{1.5} = 0.33\ \text{mol/kg}$$

Question 1

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more solute than can theoretically dissolve at a given temperature.

Question 2

Which of the following concentration units is temperature-independent?

Accepted Answer

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

Question 3

A solution is prepared by dissolving 10 g of NaCl in 90 g of water. What is the percent by mass of NaCl in the solution?

Accepted Answer

$$\frac{10}{10+90} 	imes 100\% = 10\%$$

Question 4

Which of the following statements best explains why increasing temperature usually increases the solubility of solids in liquids?

Accepted Answer

Higher temperature provides more kinetic energy, allowing more solute particles to break apart and dissolve.

Question 5

According to Henry's Law, what happens to the solubility of a gas in a liquid if the partial pressure of the gas above the liquid is doubled?

Accepted Answer

The solubility of the gas doubles.

Question 6

Which of the following best describes the phrase 'like dissolves like'?

Accepted Answer

Polar solutes dissolve best in polar solvents, and nonpolar solutes dissolve best in nonpolar solvents.

Question 7

A diver ascends too quickly from deep water, causing nitrogen gas to come out of solution in the blood. This phenomenon is best explained by:

Accepted Answer

A rapid decrease in pressure reduces the solubility of nitrogen, causing it to form bubbles.

Question 8

Which of the following would increase the amount of CO$$_2$$ dissolved in a soft drink?

Accepted Answer

Increase the pressure of CO$$_2$$ above the liquid and decrease the temperature.

Question 9

Which of the following is the correct formula for mole fraction ($$X_A) of $$component A in a solution?

Accepted Answer

$$X_A = \frac{	ext{moles of A}}{	ext{sum of moles of all components}}$$

Question 10

A solution is prepared by dissolving 0.5 mol of glucose in 1.5 kg of water. What is the molality ($$m) of $$the solution?

Accepted Answer

$$m = \frac{0.5}{1.5} = 0.33\ 	ext{mol/kg}$$

Question 11

Which of the following would be LEAST soluble in water at a constant temperature?

Accepted Answer

A nonpolar molecular compound

Question 12

If you have a saturated solution and you cool it down, what will most likely happen?

Accepted Answer

Some solute will precipitate out of solution.

Question 13

Which of the following best explains why warming ocean water leads to lower oxygen levels for marine life?

Accepted Answer

The solubility of gases in water decreases as temperature increases.

Question 14

A solution contains 0.2 mol NaCl and 0.8 mol H$$_2O. $$What is the mole fraction of NaCl?

Accepted Answer

$$X_{	ext{NaCl}} = \frac{0.2}{0.2+0.8} = 0.2$$

Question 15

Which of the following would NOT increase the amount of a gas dissolved in a liquid?

Accepted Answer

Heating the solution

Question 16

A chemist wants to prepare a saturated solution of KNO$$_3 at 60$^\circC. $$What should she do if she accidentally adds too much KNO$$_3$$?

Accepted Answer

Remove the excess undissolved KNO$$_3$$ after stirring.

Question 17

Which of the following is true about the effect of pressure on the solubility of solids in liquids?

Accepted Answer

Pressure has little to no effect on the solubility of solids in liquids.

Question 18

A 2.0 M NaCl solution is prepared by dissolving NaCl in water. Which of the following best describes the molarity of the solution?

Accepted Answer

$$M = \frac{	ext{moles of NaCl}}{	ext{liters of solution}}$$

Question 19

Which of the following real-life scenarios is an example of Henry's Law in action?

Accepted Answer

Carbon dioxide escaping from a soda when the bottle is opened.

Solubility and Solutions: General Chemistry II Study Notes (CHM 1046, Chapter 11.3)

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