Zadatak Uticaj kompleksa na pH

nobody's picture

Kolika je molarna rastvorljivost AgSCN u višku Na2S2O3 čija koncentracija posle rastvaranja iznosi 0,01 mol/dm3? P(AgSCN) = 1,1·10-12, logβ1 = 8,82; logβ2 = 13,46; logβ3 = 14,15

(RAgSCN = 0,00578 mol/dm3)

milicaradenkovic's picture

AgSCN----------------->Ag+ +SCN-

Ag+ +2S2O32- ------------------>Ag(S2O3)23-

AgSCN+2S2O32---------------------->Ag(S2O3)3-+SCN-

Kc=(Ag(S2O3)3-)*(SCN-)/(S2O32-)2

Kc=Ksp*Kf=1.1*10(-12)*2.88*10(13)=31.68

Kf=2.88*10(13) jer je logb2=13.46

31.68=x2/(0.01-2*x)2

{Ag(S2O3)3-}={SCN-}

x/(0.01-2*x)=5.63

x=5.63*(0.01-2*x)

x=0.0563-2*5.63*x

x+2*5.63*x=0.0563

x=0.0563/12.26=0.0046

R(AgSCN)=x=0.0046 mol/l greska je u resenju.