The molar solubility of `Cd(OH)_(2)` is `1.84xx10^(-5)M` in water. The expected solubility of `Cd(OH)_(2)` in a buffer solution of pH = 12 is

Options

A. `2.49/1.84 xx10^(-9)M`
B. `2.49xx10^-(10)`
C. `6.23xx10^(-11)`
D. `1.84xx10^(-9)`

Answer

B

Explanation

`Cd(OH)_(2) to Cd^(2+) + 2OH^(-)`
`K_(sp)=[Cd^(2+)][OH^(-2)]`
Solubility `s=[Cd^(2+)]=K_(sp)/([OH^(-2)])`
pH of the buffer =12
pOH = 2, `[OH]=10^(-2)`
`K_(sp)=4s^(2)=4(1.84xx10^(-5))^(3)`
`[Cd^(+2)]=(4[1.84xx10^(-5)]^(3))/(10^(-4)) = (4xx6.23xx10^(-15))/10^(-4) =2.49xx10^(-10)M`