求一道分析化学答案,急

Question

求一道分析化学答案,急

Answer 1

pH=8.00
S2-的分布系数
=[S2-]/{ [H2S]+[HS-]+[S2-]}
=Ka1*Ka2 /{[H+]^2 +[H+]*Ka1 +Ka1*Ka2}
=(1.3*10^-7 *7.1*10^-15) /{ (10^-8.00)^2 + (10^-8.00)*(1.3*10^-7) +(1.3*10^-7 *7.1*10^-15)}
=6.6*10^-7

Ag+的分布系数
=[Ag+] /{[Ag+]+[Ag(NH3)+] +[Ag(NH3)2+]}
=1/ { 1 +β1*[NH3] + β2*[NH3]^2}
=1/ {1+10^3.24 *0.01 +10^7.05 *(0.01)^2}
=8.8*10^-4

Ag2S 2Ag+ +S2-
2s s
[Ag+]=2s *8.8*10^-4
[S2-]=s *6.6*10^-7
Ksp(Ag2S)=[Ag+]^2 *[S2-]=(2s *8.8*10^-4)^2 *(s *6.6*10^-7)=2.0*10^-49
s=4.6*10^-13 mol/L