Chapter 13 Practice Test

Question 1

What is a saturated solution?

Answer 1

A saturated solution is a solution that contains the maximum possible concentration of solute (at a given temperature).

Question 2

Which of the following best describes Point 5 on the graph?

Answer 2

At this point, the solution is supersaturated. It has more dissolved solute (at a given temperature) than would normally be expected.

Question 3

A 1.00 L aqueous solution of sucrose (C12H22O11 ) has a concentration of 1.58 M. Which of the following values is not needed to calculate the molality, m?

Answer 3

the density of the solute

Question 4

Suppose that you added 19.8 g of MgCl2 to 0.250 L of water. If the density of pure water is 1.00 g / mL and the density of the final solution is 1.089 g / mL, what is the volume (in liters, L) of the final solution?

Answer 4

0.248 L

Question 5

Find the molality of an MgCl2 solution that has 19.8 g of solute in 0.65 L of H2O. The molar mass of MgCl2 = 95.22 g / mol MgCl2. Assume that the density of water is 1.00 g / mL.

Answer 5

0.32 mol / kg

Question 6

Suppose that you have a solution of battery acid that has a molarity of 3.83 M. The molar mass of the solute is 98.08 g / mol. What is the mass of the solute in one liter of the battery acid? (Assume one liter is an exact number.)

Answer 6

0.376 kg

Question 7

We often speak of reactions in aqueous solution. This means events that occur in water. When a solute dissolves in water, the solute is hydrated by water. Which statement best describes what happens in a hydration event?

Answer 7

In a hydration event, an ion is surrounded by water molecules through an exothermic process.

Question 8

The value for ΔH for a solvation reaction can be measured by a calorimeter. Which statement correctly describes the value for ΔH for a solvation event?

Answer 8

ΔH is positive for an endothermic reaction. Heat energy has to be input as a reactant for this reaction to proceed

Question 9

Look carefully at the two equations for endothermic and exothermic reactions.

solute + solvent solution + heat (exothermic)

solute + solvent + heat solution (endothermic)

Which statement is not true relative to these two equations?

Answer 9

Raising the temperature in an exothermic equilibrium circumstance will favor the dissolving of more solute in the solution.

Question 10

Which of the following processes does not use energy?

Answer 10

particle interactions (in the generation of a solution) that result in a buildup of attractive forces

Question 11

Which of the following mixtures would be considered the most miscible?

Answer 11

water and iodine

Question 12

Look at the diagram of an extraction.

Which statement best explains why iodine transfers from the water to the hexane?

Answer 12

Both iodine and hexane are relatively nonpolar

Question 13

Suppose that a solution of oxygen and water has a Henry’s law constant value of 3.9 × 10^3 atm at 25°C. What other value do you need in order to calculate the mole fraction of oxygen in solution?

Answer 13

Poxygen

Question 14

Which of the following best describes mole fraction?

Answer 14

a ratio of the number of moles of a substance in a mixture to the total number of moles in the mixture

Question 15

A solution is made up of mixing 3.81 g of naphthalene (C10H8 ) and 87.5 g benzene (C6H6 ). What is the vapor pressure of benzene above the solution?
Vapor pressure of benzene (P°solvent ) is 0.1252 atm.
The molecular weight of naphthalene is 128.17 g / mol and the molecular weight of benzene is 78.0 g / mol.

Answer 15

0.122 atm

Question 16

Which of the following is not an example of a colligative property?

Answer 16

solute-concentration elevation

Question 17

Raoult’s law states that vapor pressure of a solvent ____ when a non-volatile solute is added.

Answer 17

decreases

Question 18

If the vapor pressure of a solution is directly proportional to the mole fraction of solvent present, the solution is said to be what?

Answer 18

ideal

Question 19

What is the molality of the solution made by dissolving 5.0 grams of sugar (C12H22O11 ) in 125 g of water?

Answer 19

0.12 moles / kg

Question 20

A mass of 0.627 g of an unknown hydrocarbon is dissolved in 100.0 g of benzene (C6H6 ). The solution boils at 80.23°C. The normal boiling point of benzene is 80.10°C. What is the molecular formula of the unknown compound?

Kb for benzene is 2.64°C kg / mol.

Answer 20

C10H8

Question 21

How does increasing the temperature of a solution change the osmotic pressure?

Answer 21

The osmotic pressure will increase

Question 22

1.0 g of bovine insulin (a protein) is dissolved in 1.0 L of water. The solution is measured to have an osmotic pressure of 3.1 mm Hg at 25°C. What is the molecular weight of bovine insulin?

Answer 22

6.0 × 10^3 g / mol

Question 23

In some electrolytes, the ions do not exist completely independently, even when ionization is complete. Temporary ion pairs form. Because of temporary ion pair formation, the apparent values of ν may be ____

Answer 23

smaller than expected

Question 24

What is the boiling point of a solution that contains 5.0 g of NaCl dissolved in 25 g of water (Kb for water is 0.51)?

Answer 24

103.5°C

Question 25

What is the difference between a suspension and a colloid?

Answer 25

Colloids settle out in years. Suspensions settle in a few hours or days.