Question

Calculate the concentration of Bi³⁺ and S^2- in a solution when 45 g of Bi₂S₃ is dissolved in 300 mL of water if the K_sp = 1.1x10^-73

Answer 1

mass of Bi2S3 = 45 g

Bi2S3   --------------> 2 Bi3+ +   3 S2-

                                   2 S           3 S

Ksp = [Bi3+]^2[S2-]^3

1.1 x 10^-73 = (2S)^2 (3S)^3

1.1 x 10^-73 = 108 S^5

S = 1.00 x 10^-15 M

concentration of Bi3+ = 2.0 x 10^-15 M

concenetration of S2- = 3.0 x 10^-15 M