Given that `2 xx 10^(-4)` mole each of `Mn^(2+) and Cu^(2+)` was contained in one litre of a 0.003 M `HCIO_4` solution, and this solution was saturated with `H_2S.` Determine whether or not each of these ions, `Mn^(2+) and Cu^(2+)`, will precipitate as sulphide. The solubility of `H_2S,` 0.1 mole per litre, is assumed to be independent of the presence of other materials in the solution. `K_(sp) (MnS)=3 xx 10^(-14), K_(sp) (CuS)=8 xx 10^(-37)`
`K_(1) and K_2` for `H_2S" are "1 xx 10^7 and 1.1 xx 10^(-14)` respectively. Also, calculate the percentage of Cu remaining unprecipitated. Will Mns precipitate if the above solution is made neutral by lowering the `[H^+]" to "10^(-7)M?`

Answer

CuS precipitates; `3.27 xx 10^(-14)%,` MnS precipitates