Question

The maximum amount of nickel(II) cyanide that will dissolve in a 0.236 M nickel(II) acetate solution is

Answer 1

Solubility equillibrium of Ni(CN)2 is as follows

Ni(CN)2(s) <--------> Ni²⁺(aq) + 2CN^-(aq)

Ksp = [Ni²⁺] [CN^-]² = 3.0×10^-23M²

Initial concentration

[Ni²⁺ ] = 0.236

[CN^-] = 0

change in concentration

[Ni²⁺] = +x

[CN^-] = +2x

Equillibrium concentration

[Ni²⁺] = 0.236 +x

[CN^- ] = 2x

So,

( 0.236+x)(2x)2= 3.0×10^-23

solving for x

x = 5.637×10-12

Therefore

molar solubility of Ni(CN)2 in Ni(CH3COO)2 = 5.637×10^-12 mol /L

molar mass Ni(CN)₂ ÷ 110.729g/mol

mass of 5.637×10^-12 mol of Ni(CN)2 = 110.729g/mol × 5.637×10^-12mol = 6.24×10^-10g

Solubility of Nickel(II)cyanide in 0.236M nickel(II)acetate = 6.24×10^-10g/L