Zadatak Uticaj kompleksa na pH
Submitted by nobody on Mon, 06/16/2014 - 13:49

Forums:
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)
AgSCN----------------->Ag+
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.