Question

Demonstrate whether or not silver oxalate is precipitated by mixing 40.0 mL of Ag + 4.75 x 10 -5 M with 60.0 mL of a solution of Na 2 C 2 O 4 whose density is 0.18 g / mL and which is 0.80% w / w of this salt. The KPS Ag2C2O4 is 3.5 x10-11.

Answer 1

using M1V1 = M2V2   we find final conc of Ag+

M1 = 4.75 x 10^ -5 , V1 = 40 ml , V2 = 40+ 60 = 100 ml = vol of final solution

4.75 x 10^ -5 x 40 = M2 x 100

M2 = 1.9 x 10^ -5

Na2C2O4 mass = vol x density

          = 60 ml x 0.18 g/ml

        = 10.8 g

since given solution is 0.8 % w/w ,Na2C2O4 mass = ( 0.8/100) x 10.8 = 0.0864 g

Moles of Na2C2O4 = mass / Molar mass

          = 0.0864 g / 134g/mol = 0.000645

[Na2C2O4] = moles / vol = 0.000645 /0.1 = 0.00645 M     ( vol = 100 ml = 0.1L)

[C2O4^2-] = 0.00645 M            

Ag2C2O4 (s) <--> 2Ag+ (aq) + C2O4^2- (aq)

Ionic product = [Ag+]^2 [C2O42-]

        = (1.9 x 10^ -5)^2 ( 0.00645)

       = 2.32 x 10^ -12

Ionic product < Ksp of Ag2C2O4

hence we donot get any precipitate