Unit 12: Solutions

Practice Test

Objective 1: Describe the properties of solution and solvation (p. 453 – 458)

Determine whether the statements about the observable properties of solutions are TRUE (T) or FALSE (F)

___ 1.  Solutions are always homogeneous mixtures.

___ 2.  A solution always involves a solid or gas dissolved in a liquid.

___ 3.  In general, increasing agitation will increase the rate of solvation.

___ 4.  Soluble ionic compounds dissociate into ions when dissolving.

Select the best choice.

___ 5.  Which of the following is an electrolyte?

A)  Potassium chloride (KCl) C) ethanol (CH3CH2OH)

B)  water (H2O) D) chlorine (Cl2)

___ 6.  A 95% solution of ethanol contains both liquid ethanol and water. Ethanol is considered ______in water.

A)  Miscible B) immiscible C) suspended D) insoluble

___ 7.  Brass, an alloy of zinc and copper, is an example of which solute-solvent combination?

A)  solid-solid B) liquid-solid C) liquid-liquid D) gas-gas

___ 8.  What is the mass of the solution when 1 pound of salt is dissolved in 20 pounds of water?

A.  19 Pounds.

B.  20 Pounds.

C.  Between 20 and 21 pounds.

D.  21 pounds.

E.  More than 21 pounds.

8.  Potassium bromide is soluble in water. During this process, water molecules “pull” ions from the crystal and surround them.

a)  State one name for this process. ______

b)  In the box below, draw three water molecules, showing the correct orientation of each water molecule toward the bromide ion (Br-). Label the appropriate partial charges on at least one water molecule.

Score box / □ A= 10/10 (100) / □ B= 9/10 (90) / □ NY

Objective 2: Explain factors affecting solubility and interpret solubility curves. (p. 457-459)

Directions: Using the solubility curve, answer the following questions.

1.  How much KI can you dissolve in 150 grams of water at 10 ºC ______

2.  What temperature does the water need to be to dissolve 70 grams of HCl in 100g H₂O? ______

3.  A solution is made in such a way that it contains 95 grams of NH4Cl dissolved in 100 g of H2O water at 80oC. Is the solution saturated, unsaturated, or supersaturated? ______

4.  90 g of NaNO3 is added to 100 g H2O at 60oC. To what temperature must the solution be lowered to in order to produce a saturated solution? ______

5.  If 50 grams of NaCl is added to 50 grams of water at 90ºC, how many grams will not dissolve? ______

6.  Which salt shows the greatest increase in solubility from 0oC to 100oC? ______

______

  1. Use the “Like dissolves Like” rule of thumb to predict which of the following compounds is soluble in CCl4, a nonpolar solvent

A)  NaOH b) NH3 c) I2 D) HF

  1. Which set of conditions represents the greatest solubility of O2(g) in water?

A)  1 atm and 25oC B) 2 atm and 25 oC C) 1 atm and 5oC D) 2 atm and 5oC

  1. Ethan is making a salt solution using solid lithium fluoride and water. After adding a few spoonfuls of the salt, he reaches the saturation point. What he can do to make more lithium fluoride dissolve?

A)  agitate the solution using a stirring rod

B)  increase the surface area of the salt by crushing it

C)  increase the atmospheric pressure on the surface of the solution

D)  heat the solution on a hot plate

Score box / □  A= 9/9 (100) / □  B= 8/9 (89) / □  NY

Objective 3: Determine the molar concentration of solutions and describe how to prepare them. (p. 464- 466)

Directions: Solve the following problems, including all WORK, FORMULAS, UNITS, and SIG FIGS. Place a BOX around your final answer.

1.  How many moles of CaCl2 are required to prepare 3.00 liters of 1.20 M CaCl2?(1)

2.  You have a 0.83-L solution that contains 2.5 grams of NaCl. What is the molarity of the solution? (2)

3.  How many grams of KNO3 will be required to prepare 500.0 mL of 0.965 M KNO3 ? (2)

4.  Describe in words how you would make the solution found in problem 3.(1)

5.  Suppose you need 100 mL of a 0.10 M solution of NiCl2, but all you have is a solution that is 0.25 M. Calculate the volume of the 0.25 M solution that must be diluted to give 100 mL of 0.10 M solution. (2)

Salt is added to water and the mixture is stirred until no more salt dissolves. The salt that does not dissolve is allowed to settle out. What happens to the concentration of salt in solution if water evaporates until the volume of the solution is half the original volume? (Assume temperature remains constant.)

6.  The concentration

A) increases B) decreases C) stays the same.

7.  What is the reason for your answer to question 20?

A) There is the same amount of salt in less water. C) More solid salt forms.

B) Salt does not evaporate and is left in solution. D) There is less water.

Score box / □  A= 9/9 (100) / □  B= 8/9 (88) / □  NY