Your Ksp for AgBr is eqn 1.
Your Kf for Ag(S2O3^-2)^3- is eqn 2.
Add equn 1 to eqn 2 to get
AgBr(s) + 2(S2O3)^3- ==> Br^- + [Ag(S2O3)2]^3-
Write the equilibrium expressiion for that which equals Ksp*Kf.
Then substitute 0.02 for Br^- and 0.02 for [Ag(S2O3)]^3- and solve for (S2O3)^2-. Remember AgBr(s) does not appear in the equilibrium expression. Looks like (1) is the answer but you should confirm that yourself.
Calculate how many moles of Na2S2O3 must be added to dissolve 0.020 mol AgBr in 1.0 L of water at 25°C (assume constant volume).
AgBr(s) ↔ Ag+(aq) + Br−(aq)
Ksp = 3.3 x 10^−13
Ag+(aq) + 2S2O32−(aq) ↔ [Ag(S2O3)2]3−(aq)
Kf = 2.0 x 10^13
(1) 0.0078 mol (2) 0.048 mol (3) 0.040 mol (4) 0.024 mol (5) 0.016 mol
1 answer