Question

6. At 298 K, the equilibrium constant for the below reaction is 4.17 x 103. What is the concentration of Clat equilibrium? Pb2+ (aq) + 2 C1" (aq) = PbCl2 (5) (a) 20.2 M (b) 0.078 M (c) 10.1 M (d) 0.039 M

Answer 1

Pb2+(aq) + 2Cl-(aq) ------------------> PbCl2(s)

S                 2S

Keq = 1/[Pb2+] [Cl-]^2

4.17 x 10^3 = 1/ (S)(2S)^2

4.17 x 10^3 = 1/ 4S^3

S =0.0391

[Cl-] = 2S = 2 x 0.0391 = 0.0783 M

answer : b) 0.0783 M