Question

A) Consider the insoluble compound zinc hydroxide, Zn(OH)₂. The zinc ion also forms a complex with ammonia. Write a balanced net ionic equation to show why the solubility of Zn(OH)₂(s) increases in the presence of ammonia and calculate the equilibrium constant for this reaction.

For Zn(NH₃)₄²⁺, K_f = 2.9×10⁹. Specify states such as (aq) or (s) and provide K.

K = ______

B) Consider the insoluble compound nickel(II) hydroxide, Ni(OH)₂. The nickel ion also forms a complex with cyanide ions. Write a balanced net ionic equation to show why the solubility of Ni(OH)₂(s) increases in the presence of cyanide ions and calculate the equilibrium constant for this reaction.

For Ni(CN)₄^2-, K_f = 1.0×10³¹. Specify states such as (aq) or (s) and provide K.

K = ______

C) Consider the insoluble compound zinc carbonate, ZnCO₃. The zinc ion also forms a complex with hydroxide ions. Write a balanced net ionic equation to show why the solubility of ZnCO₃(s) increases in the presence of hydroxide ions and calculate the equilibrium constant for this reaction.

For Zn(OH)₄^2-, K_f = 2.9×10¹⁵. Specify states such as (aq) or (s) and provide K.

K = ______

Answer 1

A) Zn(OH)2 (s) Zn^2+ (aq) + 2OH^- (aq); Ksp = 4.5×10^(-17)

Zn^2+ (aq) + 4NH3 (aq) [Zn(NH3)4]^2+ (aq); Kf = 2.9×10^9

By adding the above two equations, you will get

Zn(OH)2 (s) + 4NH3(aq) [Zn(NH3)4]^2+ (aq) + 2OH^-; K = Ksp × Of = 1.305×10^(-7)

Similarly, you can approach for the remaining two parts B and C.