Chem 1B
Dr. White
Worksheet 12: Factors Affecting Solubility KEY
1. Consider ZnCO3 (s) in equilibrium with its ions. Determine if the solubility increases,
decreases or stays the same in each of the following cases. The Kf for Zn(CN)42- is
2.1 x 1019 and ΔH>0 for dissolving the solid in water.
a. pH is decreased
Solubility Increases
If the pH is decreased, the [H3O+] increases. H3O+ will react with CO32-and deceases the
concentration of CO32- thus the Ksp reaction shifts right towards the ions,
b. 0.10 M Na2CO3 is added to the solution
Solubility Decreases
c. 0.10 M NaCN is added.
Solubility Increases
d. The temperature is increased.
Solubility Increases
2. Consider AgI (s) in equilibrium with its ions. Determine if the solubility increases,
decreases or stays the same in each of the following cases. The Kf for Ag(NH3)2+ is
1.7 x 107 and ΔH<0 for dissolving the solid in water.
a. pH is increased
Solubility Stays the same
b. Ag+ is removed by adding NaCl.
Solubility Increases
c. 0.10 M NH3 is added.
Solubility Increases
d. The temperature is decreased.
Solubility Increases
Chem 1B
Dr. White
3. In black and white film developing, excess AgBr is removed from the film negative by
“hypo”, an aqueous solution of sodium thiosulfate (Na2S2O3), which forms the complex ion
Ag(S2O3)23-. Calculate the solubility of AgBr in water and in 1.0 M hypo. Kf of Ag(S2O3)23- is
4.7 x 1013 and Ksp of AgBr is 5.0 x 10-13 (ans: in water S = 7.1 x 10-7 M and in hypo S = 0.45
M)
Chem 1B
Dr. White
4. Calculate the solubility of zinc hydroxide, Zn(OH)2, in 1.00 M NaOH.
Ksp = 3.0 × 10-16 for Zn(OH)2, Kf = 3.0 × 1015 for Zn(OH)42- (ans: 0.24 M)
Chem 1B
Dr. White
5. Calculate the solubility of copper(II) carbonate, CuCO3, in 1.00 mol L-1 NH3. Ksp = 3.0 × 1012
for CuCO3, Kf = 5.6 × 1011 for Cu(NH3)42+ (ans: 0.16 M)