Ch. 15, 16, & 19.7 equilibrium I         test       85 points                                AP chem

 

 

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.  In regards to the reaction:   NH4Cl (s)     NH3 (g)  +  HCl (g)  at equilibrium was disturbed by ___; what is the effect on the relative partial pressure of ammonia after the system reestablishes equilibrium compared to its pre-disturbance value  ?   Justify / rationalize your response.  [15 points]

 

a.  reduce the container’s volume, where [NH3] = [HCl] prior to the disturbance

 

b. reduce the container’s volume, where [NH3] > [HCl] prior to the disturbance

 

c.  cool the container


 

2.  Based on the reaction:  N2(g)  +  3 H2(g)     2 NH3 (g) ;   Kc  =100.  What is the numerical value of Kc for  __; justify your response.  [10 points]

 

a.  4 N2(g)  +  12 H2(g)     8 NH3 (g)

 

 

b.  2 NH3 (g)  ⇄  N2(g)  +  3 H2(g)    

 

 

3.  Write the equilibrium constant, Kc, expression for the following reactions:  [15 points]

 

a.  NH4Cl (s)     NH3 (g)  +  HCl (g) 

 

 

b.  C2H6 (l)  +  O2(g)    CO2 (g)  +  H2O (l)

 

 

c.  the net ionic equation for the reaction, where mix aqueous solutions of calcium nitrate and potassium phosphate

 

 

 

4.  What is the pH of 25.0 mL of 10.0 mM methylamine ?  [15 points]

 

 

5.  old topics:  Give the formulas to show the reactants and products for the following chemical reactions.  Each occurs in aqueous solution unless otherwise indicated.  Represent substances in solution as ions if the substance is extensively ionized.  Omit formulas for any ions or molecules that are unchanged by the reaction.   [9 points]

 

a.  mix aqueous solutions of acetic acid and sodium bicarbonate

 

b.  bubble carbon dioxide in a solution of potassium hydroxide

 

c.  add concentrated ammonia to a solution of tin (II) chloride

 

6.  What is the pH of  25.0 mL of  ___ ?  [6 points]

 

a.   10.0 mM HCl

 

b.  10.0 mM KOH

 

 

7.  What is the pH of 25.0 mL of 10.0 mM methylamine nitrate ?  [15 points]