Question

A solution contains 1.25×10^-2 M nickel(II) acetate and 1.02×10^-2 M silver nitrate.
Solid potassium hydroxide is added slowly to this mixture.

A. What is the formula of the substance that precipitates first?

B. What is the concentration of hydroxide ion when this precipitation first begins?
[OH^-] =  

Answer 1

Ksp of Ni(OH)2 = 2.8 x 10^-16

Ksp of AgOH = 2.0 x 10^-8

A)

formula of the substance that precipitates first = Ni(OH)₂

B)

Ni(OH)2   -------------> Ni2+   + 2 OH-

Ksp = [Ni2+][OH-]^2

2.8 x 10^-16 = (1.25 x 10^-2) x [OH-]^2

[OH-] = 1.50 x 10^-7 M