CHM 2046C Module 12 Chapter 18 Sample Exam Answers

 

Part G: Writing Ksp Expressions   10 points

 

Write the dissociation reactions for the following insoluble salts, then setup the Ksp expressions: (aq)

 

1.   Cu(OH)2  (s)   +   HOH  (l)    ß à  Cu2+ (aq)     +  2 OH1- (aq)

 

 

Ksp = [Cu2+][OH1-]2                                                        Ksp = 2.2 x 10 -20

 

 

 

2.   MgCO3  (s)   +   HOH  (l)    ß à   Mg2+ (aq)   +    CO32- (aq)

 

 

Ksp = [Mg2+][ CO3 2-]                                                    Ksp = 6.8 x 10 -6

 

 

 

3.   Al2(SO4)3  (s)   +   HOH  (l)    ß à 2 Al3+ (aq)   +  3  SO42- (aq)

 

 

 

Ksp = [Al3+]2[ SO42-]3                                                     Ksp = 9.8 x 10 -21

 

 

 

4.   Cu2S      (s)   +   HOH  (l)      ß à    2 Cu1+ (aq)   +    S2- (aq)

 

 

Ksp =    [Cu1+]2[S2-]                                                                               Ksp = 2.2 x 10 -48

 

 

 

5.   Mg(OH)2  (s)   +   HOH  (l)    ß à   Mg2+ (aq)     +  2 OH1- (aq)

 

 

Ksp =    [Mg2+][OH1-]2                                                       Ksp = 5.6 x 10 -12

 

 

 

Additional Ksp Expressions:

 

 

McMurry Reference: Section 15.10. Note Worked Example 15.7 page 619.

Work problem 15.20 page 619.

Additional Problems 15.90 and  15.91 on page 641.

 

Kotz Reference: Chapter 18 Section 18.4 p873-878

Try Exercise 18.11 page 875

P 896 Questions #37 and #38 for addition samples