In: Chemistry
Calculate the equilibrium concentration of Ag+(aq ) in a solution that is initially 0.170 M AgNO3 and 0.990 M NH3, and in which the following reaction takes place: Ag+(aq)+2NH3(aq)=Ag(NH3)2+(aq) (Kf = 1.70x107)
Given that
[AgNO3] = 0.170 M
[NH3] = 0.990 M
Kf = 1.70x107
0.170M will react with NH3 and there will be zero amount of Ag+ left after reaction
However the complex formed will generate more amount of Ag+ due to dissociation
Ag+(aq) + 2NH3(aq) = Ag(NH3)2+(aq)
Initial 0.170 0.990 0
Change -0.170 -2(0.170) 0.170
Equilibrium +x 0.65 +2x 0.170 - x
Kf = [0.170-x] / [x][0.65+2x]^2
we may ignore x in denominator and numerator in addition and subtraction
Therefore
1.70x107 = [0.170] / [x] (0.65)2
x = 2.367 X 10-7 M