Q: According to Henry's Law, which equation correctly relates the solubility of a gas in a liquid to the pressure of the gas above the solution?

$$S_{gas} = k_H \times P_{gas}$$

Q: A pressure of 1.2 bar of CO$$_2 is $$required to maintain a 0.32 mol L$$^{-1} CO$_2$$ concentration in soda. What is the Henry's Law constant for CO$$_2 in $$this scenario?

$$k_H = 0.27 \text{ mol L}^{-1} \text{ bar}^{-1}$$

Q: Which of the following is the correct formula for mass percent of a solute in a solution?

$$\text{mass percent} = \frac{\text{mass of solute}}{\text{total mass of solution}} \times 100$$

Question 1

According to Henry's Law, which equation correctly relates the solubility of a gas in a liquid to the pressure of the gas above the solution?

Accepted Answer

$$S_{gas} = k_H 	imes P_{gas}$$

Question 2

A pressure of 1.2 bar of CO$$_2 is $$required to maintain a 0.32 mol L$$^{-1} CO$_2$$ concentration in soda. What is the Henry's Law constant for CO$$_2 in $$this scenario?

Accepted Answer

$$k_H = 0.27 	ext{ mol L}^{-1} 	ext{ bar}^{-1}$$

Question 3

Which of the following statements about the effect of temperature on solubility is correct?

Accepted Answer

The solubility of gases in water decreases with increasing temperature.

Question 4

A 2.5 g sample of groundwater contains 5.4 μg of Zn$$^{2+}. $$What is the concentration of Zn$$^{2+} in $$ppm?

Accepted Answer

$$2.2 	ext{ ppm}$$

Question 5

Which concentration unit is temperature-independent and defined as moles of solute per kilogram of solvent?

Accepted Answer

Molality ($$m)$$

Question 6

A solution is prepared by mixing 28.8 g of Pb(NO$$_3$$)$$_2$$ with 1152 g of water to make 1.20 L of solution. If the density of the solution is 1.20 g mL$$^{-1}$$, what is the mass percent of Pb(NO$$_3$$)$$_2$$?

Accepted Answer

$$20.0\%$$

Question 7

Which of the following is the correct formula for mass percent of a solute in a solution?

Accepted Answer

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

Question 8

If the mole fraction of phenol ($$X_p) in a $$solution is $$9.98 	imes 10$$^{-3}$$, what is the mole fraction of water (X$$_{H_2O}$$) in the same solution?

Accepted Answer

$$X_{H_2O} = 0.990$$

Question 9

Which of the following best explains why the Henry's Law constant for NH$$_3 is $$much higher than for other gases?

Accepted Answer

NH$$_3$$ forms strong hydrogen bonds with water, increasing its solubility.

Question 10

Which of the following is NOT a way to express concentration of a solution?

Accepted Answer

Density

Question 11

A solution contains 1.09 mol of glycerol and 5.55 mol of water. What is the mole fraction of glycerol?

Accepted Answer

$$X_{glycerol} = 0.164$$

Question 12

Which of the following statements is true regarding molarity and molality?

Accepted Answer

Molality is defined as moles of solute per kilogram of solvent, while molarity is moles of solute per liter of solution.

Question 13

A solution is prepared by dissolving 28 g of NaOH in enough water to make 100 g of solution. What is the mass percent of NaOH?

Accepted Answer

$$28\%$$

Question 14

Which of the following concentration units is most appropriate for expressing the amount of a pollutant in a lake at very low concentrations?

Accepted Answer

Parts per million (ppm)

Question 15

A solution is made by mixing equal masses of glycerol (C$$_3H$_8O$_3) $$and water. If the density of the solution is 1.10 g mL$$^{-1}$$, what is the molarity of glycerol in the solution?

Accepted Answer

$$5.98 	ext{ mol L}^{-1}$$

Question 16

Which of the following is true about the sum of mole fractions in a solution?

Accepted Answer

The sum of mole fractions of all components equals 1.

Question 17

Why does molarity change with temperature while molality does not?

Accepted Answer

Molarity depends on the volume of solution, which changes with temperature.

Question 18

If the pressure of a gas above a solution is increased, what happens to the concentration of the gas dissolved in the solution at equilibrium?

Accepted Answer

It increases.

Question 19

Which real-life event is associated with the rapid release of dissolved gases from a lake, as discussed in the study materials?

Accepted Answer

The Lake Nyos Tragedy

Chapter 12: Solutions – Factors Affecting Solubility and Concentration Expressions

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