Ch. 15 & 16 equilibrium test [85 points] AP Chemistry

Show your work in an organized manner, includes any relevant equation / formula, proper units in your work / answer, and the proper number of significant figures in your answer.

 

1. Equilibrium constant. Justify your answer. [15 points]

a. If Kc = 100 for the reaction: N2 + 3 H2 <-->  2 NH3,

then Kc = ___ for the reaction: 2 N2 + 6 H2  <-->   4 NH3.

b. If Kc = 100 for the reaction:  3 Ca 2+(aq)  + 2 PO4 3-(aq)  <-->  Ca3(PO4)2 (s)

then Kc = ___ for the reaction:  Ca3(PO4)2 (s)  <-->  3 Ca 2+(aq)  + 2 PO4 3-(aq) 

c. If Kc = 100 for the reaction: 2 H2 (g) + O 2 (g)   <-->   2 H2O (g)

then Kp = _____ for this reaction at 25 ° C.

2. At 400. K, does the reaction: 2 NH3 (g)  -->   N2 (g) + 3 H2 (g) occur, where [NH3] = 1.0 M, [N2] = 1.0 mM, and [H2] = 1.0 µ M ? Justify your answer. [15 points]


3. In the reaction: H2 + I2   <-->   2 HI    Kc = 10, determine the equilibrium concentration of HI, where the initial concentration of H2, I2, and HI are 1.0 M, 1.0 M, and 5.0 M, respectively. [15 points]

4. Determine the pH of a 125 mL aqueous solution containing 10.0 mM sodium lactate. [15 points]

 

5. In the reaction: C2H4 (g)   +   I2 (g)  <-->   C2H3I 3 (g)   +    HI (g) at equilibrium [C2H4 and C2H3I3 is an alkene and alkane, respectively] , what would happen to [C2H3I3] by the following disturbances. [justify your answer; 25 points]

a. remove I2

b. reduce the system’s volume

c. cool the system [hint: sketch the structural formulas of the compounds in the reaction]