What is the minimum pH required to prevent the precipitation of ZnS in a solution that is 0.01M ZnCl2 and saturated with 0.10M H2S ? [Given Ks p=10- 21,Ka1× Ka2=10- 20 ]

Question

What is the minimum pH required to prevent the precipitation of ZnS in a solution that is 0.01M ZnCl2 and saturated with 0.10M H2S ? [Given Ks p=10- 21,Ka1× Ka2=10- 20 ] (A) 0 (B) 1 (C) 2 (D) 4

Tardigrade Admin · Accepted Answer

Ks p=[Z n2 +][S2 -]Ke q=([. H+ ].2 [S2 -]/[H2 S]) 10- 21=0.01[S2 -]10- 20=([. H+ ].2 1 0- 19/[0.1]) S2 -=10- 19H+=10- 1

Q. What is the minimum $p H$ required to prevent the precipitation of $Z n S$ in a solution that is $0.01 M$ $Z n C l_{2}$ and saturated with $0.10 M$ $H_{2} S$ ?
[Given $K_{s p} = 1 0^{- 21}, K_{a_{1}} \times K_{a_{2}} = 1 0^{- 20}$ ]

0

1

2

4

$K_{s p} = [Z n^{2 +}] [S^{2 -}] K_{e q} = \frac{[ H ^{+} ] ^{2} [ S ^{2 -} ]}{[ H _{2} S ]}$
$1 0^{- 21} = 0.01 [S^{2 -}] 1 0^{- 20} = \frac{[ H ^{+} ] ^{2} 1 0 ^{- 19}}{[ 0.1 ]}$
$S^{2 -} = 1 0^{- 19} H^{+} = 1 0^{- 1}$

Q. What is the minimum pH required to prevent the precipitation of ZnS in a solution that is 0.01M ZnCl2​ and saturated with 0.10M H2​S ? [Given Ksp​=10−21,Ka1​​×Ka2​​=10−20 ]

0

1

2

4

Ksp​=[Zn2+][S2−]Keq​=[H2​S][H+]2[S2−]​ 10−21=0.01[S2−]10−20=[0.1][H+]210−19​ S2−=10−19H+=10−1

Q. What is the minimum $p H$ required to prevent the precipitation of $Z n S$ in a solution that is $0.01 M$ $Z n C l_{2}$ and saturated with $0.10 M$ $H_{2} S$ ?
[Given $K_{s p} = 1 0^{- 21}, K_{a_{1}} \times K_{a_{2}} = 1 0^{- 20}$ ]

$K_{s p} = [Z n^{2 +}] [S^{2 -}] K_{e q} = \frac{[ H ^{+} ] ^{2} [ S ^{2 -} ]}{[ H _{2} S ]}$
$1 0^{- 21} = 0.01 [S^{2 -}] 1 0^{- 20} = \frac{[ H ^{+} ] ^{2} 1 0 ^{- 19}}{[ 0.1 ]}$
$S^{2 -} = 1 0^{- 19} H^{+} = 1 0^{- 1}$