An aqueous solution contains 0.10 M H2S and 0.20 M HCl. If the equilibrium constants for the formation of HS^(-)fromH_(2)S" is " 1.0 xx 10^(-7) " andthat of " S^(2-) " from " 4S^(-) " ionsis " 1.2 xx 10^(-13) ,then find the concentration of S^(-2) ions in aqueous solution

An aqueous solution contains 0.10 M H2S and 0.20 M HCl. If the equilib

1.	An aqueous solution contains 0.10 M H2S and 0.20 M HCl. If the equilibrium constants for the formation of HS^(-)fromH_(2)S" is " 1.0 xx 10^(-7) " andthat of " S^(2-) " from " 4S^(-) " ionsis " 1.2 xx 10^(-13) ,then find the concentration of S^(-2) ions in aqueous solution
Answer» Solution :`underset((0.1 - x))(H_(2)S(AQ.)) hArr underset((2x + 0.29))(2H^(+) )+ underset(x)(S^(2-) )` `K_(a) = K_(a_(1)) xx K_(a_(2)) = 1.2 xx 10^(-20) ` `1.2 xx 10^(-20) = ((0.2)^(2-) [S^(2-)])/(0.1) , [S^(2-)] = 3 xx 10^(-20) `