AP Chemistry Practice Exam 2 337Part B. Time — 40 minutes
You may not use a calculator for part B.Question 4.
Answer all three of the following questions. Each question will have two parts—writing the balanced chemical
equation and answering a question about the reaction. Coefficients in the balanced chemical equation must be
in the lowest whole-number ratio. Do not include formulas for substances that remain unchanged during the
reaction. Unless otherwise noted, assume all the reactions occur in aqueous solution. If a substance is exten-
sively ionized and therefore is present as ions in solution, write its formula as ions.
Example: Hydrochloric acid is added to a lead(II) nitrate solution.(a) Excess ammonia solution is added to solid silver chloride.
Which species behaves as a Lewis acid in this reaction? Explain.
(b) Pentanol is combusted in oxygen.
If one mole of pentanol totally reacts, how many total moles of products will be formed?
(c) An ammonium chloride solution is mixed with a barium hydroxide solution.
If equal volumes of 1 M ammonium chloride and 1 M barium hydroxide are mixed, what is the lim-
iting reactant in this reaction?Question 5.
The above reaction is to be used in the analysis of an oxalate sample.(a) Outline the general procedure for the standardization of a potassium permanganate solution beginning
with primary standard sodium oxalate.
(b) Outline the calculation of the concentration of the potassium permanganate solution.
(c) Show how to calculate the percent sodium oxalate in an unknown.
(d) List the problems arising if the primary sodium oxalate solution was not dried before being weighed.
(e) Normally, sulfuric acid is used to supply the hydrogen ions for the reaction. What would be the prob-
lem of substituting hydrochloric acid for sulfuric acid?Question 6.
Five beakers (A–E) are placed on a counter top. Each contains 200 mL of a 0.10 M solution. Beaker A con-
tains Ba(OH) 2 ; beaker B contains (NH 4 ) 2 SO 4 ; beaker C contains (CH 3 ) 2 CHOH; beaker D contains
K 3 PO 4 ; and beaker E contains FeSO 4.(a) Which beaker has the lowest pH? Explain.
(b) Which two beakers may be mixed to produce a gas with a characteristic odor? Write a chemical equa-
tion for the reaction.
(c) Which of the solutions has its freezing point depressed the least? Explain.
(d) Which two solutions are basic?
(e) Which other beaker will not give a precipitate when added to beaker A? Explain.5 C O 2 24 −−++++→++ 2 MnO 4 16 H Mn^210 CO 228 H OPb + 2Cl2+ –→PbCl 2STOP. End of AP Chemistry Practice Exam 2