Name:  ______________________________            period 6                       date:  _______

Ch. 21 & 14  equilibrium 2 & electrochem  test                            [75 points]                             AP  Chemistry

For problems involving calculations, show the relevant equation (or formula and conversion factor(s)), show your work in an organized manner, put the proper units in your calculations / answer, and have the proper number of significant figures in your answer. 

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

                                                                                                Signature:  ___________________

1.  What is the pH of a 50.0 mL aqueous solution of 25 mM acetic acid and 20 mM sodium acetate after the addition of __.   [15 points]

a.  nothing

b.  10.0 mL 50.0 mM HCl

c.  5.0 mL 50.0 mM KOH

2.  What is the molar solubility of silver iodide in  __ ?   [15 points]

a.  water

b.  1.0 mM sodium iodide

c.  rationalize the relative difference in the preceding values.


3.  Balance the following redox reaction (in a basic solution)  

                                             MnO4 -   +  C2 O4 2-   ->  MnO2 + CO3 2-      [10 points]

4.  What is the equilibrium constant for the reaction:  Pb(s)   +   Ag+ (aq)   <->  Pb2+ (aq)   +   Ag (s) .  [10 points]

5.  How much time (in minutes) would be needed to coat an electrode with 0.5 g of zinc using a 888 mA current source ?  [10 points]

6.  For each of the following reactions, in part (i) write a BALANCED equation and in part (ii) answer the question about the reaction.  Coefficients should be in terms of lowest whole numbers.  Assume that solutions are aqueous unless otherwise indicated.  Represent substances in solutions as ions if the substances are extensively ionized.    [15 points]

a.  sodium metal is added to water

i.

ii.  identify the oxidizing agent

 

b.   mix solutions of iron (II) chloride and concentrated ammonia

i.

ii.  identify the Lewis acid

c.  solid sodium carbonate is added to a solution of acetic acid

i.

ii.  identify the conjugate base