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What is the concentration of Cd2+ in a saturated solution of Cd(OH)2 (Ksp= 2.5 x 10^-14) with a pH of 8.5?

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jeew-m | College Teacher | (Level 1) Educator Emeritus

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`H_2O-----gtH^++OH^-`

`Cd(OH)_2-----gt Cd^(2+)+2OH^-`

 

` PH = -log[H^+]`

     `8 =` `-log[H^+]`

`[H^+] = 10^-8 `

 

We know `K_w = [H^+][OH^-]`

Assume we have normal condtions;

So` K_w = 10^-8[OH^-] = 10^-14`

Therefore `[OH^-] = 10^-6`

`K_(sp) = [Cd^(2+)][OH^-]^2`

 

`[Cd^(2+)] = K_(sp)/[OH^-]^2`

            =`2.5 xx 10^-14/[10^-6]^2`

            = `2.5xx10^(-2)`

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