4. Using the Law of Mass Action, write the equilibrium expression for each of the following reactions.
(a) 6 I-(aq) + 2 MnO4-(aq) + 4H2O <==>
3I2(aq) + 2 MnO2(s) + 8 OH-(aq)
[I2]3[MNO2]2[OH-]8 = K
(b) 2 Cu2+(aq) + 4 I-(aq) <==>
2 CuI(s) + I2(aq)
[CuI]2[I2] = K
(c) 1/2 O2(g) + Sn2+ + 3H2O(l) <==>
SnO2(s) + 2H3O+(aq)
[SnO2][H3O+]2 = K
51. For each of the following ionic compounds, state whether the solubility will increase, decrease, or remain unchanged as a solution at pH 7 is made acidic.
The lead concentration will go up, but the iodide concentration will interact with the hydronium ions of the acid and less iodide will be present. That in turn makes the lead concentration go up.
The silver concentration will increase and the hydroxide concentration will decrease because of the hydronium ions from the acid. The hydroxide will react with the hydronium to make water and therefore there will be less hydroxide, making the silver concentration increase.
The concentration will stay the same because the phosphate ions, that which would possible react with the hydronium ions, will remain aqueous during the entire solution. That means that neither concentration will change.