5 Steps to a 5 AP Chemistry 2019

Solutions and Colligative Properties ❮ 189

1. A solution is prepared by dissolving 1.25 g of
   an unknown substance in 100.0 mL of water.
   Which of the following procedures could be used
   to determine whether the solute is an electrolyte?
   (A) Measure the specific heat of the solution.
   (B) Measure the volume of the solution.
   (C) Measure the freezing point of the solution.
   (D) Determine the specific heat of the solution.


2. What is the final K+ concentration in a solution
   made by mixing 300.0 mL of 1.0 M KNO 3 and
   700.0 mL of 2.0 M K 3 PO 4?
   (A) 4.5 M
   (B) 5.0 M
   (C) 3.0 M
   (D) 2.0 M
   3. Strontium sulfate, SrSO 4 , will precipitate when a
   solution of sodium sulfate is added to a strontium
   nitrate solution. What will be the strontium ion,
   Sr^2 +, concentration remaining after 30.0 mL of
   0.10 M Na 2 SO 4 solution are added to 70.0 mL
   of 0.20 M Sr(NO 3 ) 2 solution?
   (A) 0.14 M
   (B) 0.15 M
   (C) 0.11 M
   (D) 0.20 M
   4. Which of the following is a strong electrolyte
   when it is mixed with water?
   (A) HNO 2
   (B) KNO 3
   (C) C 2 H 5 OH
   (D) CH 3 COOH

❯ Review Questions

Use these questions to review the content of this chapter and practice for the AP Chemistry

exam. First are 16 multiple-choice questions similar to what you will encounter in Section I

of the AP Chemistry exam. Following those are two long free-response questions like the

ones in Section II of the exam. To make these questions an even more authentic practice

for the actual exam, time yourself following the instructions provided.

Multiple-Choice Questions

Answer the following questions in 25 minutes. You may not use a calculator. You may use

the periodic table and the equation sheet at the back of this book.

Experiments

Experimental procedures for solutions involve concentration units. Keeping close track of

the units may simplify the problem.

Concentration problems are concerned with the definitions of the various units. It is

possible to calculate the mass and/or volume of the solvent and solute by taking the differ-

ence between the final and initial measurements. The density, if not given, is calculated,

not measured. It is important to recognize the difference between the values that must be

measured and those that can be calculated. Moles are also calculated, not measured.

Do not forget that nearly all the concentration units use the total for the solution in

the denominator. For these units it is important to remember to combine the quantities

for the solvent and all solutes present.

Common Mistakes to Avoid

1. In molarity problems, be sure to use liters of solution.


2. Make sure your units cancel, leaving you with the units desired in your final answer.


3. Round off your final numerical answers to the correct number of significant figures.


4. Remember, most molecular compounds––compounds containing only nonmetals––do
   not ionize in solution. Acids are the most common exceptions.

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