Question

In a solution saturated with CuBr, what is the maximum concentration of Ag⁺ that can exist without precipitating?

Enter your answer in units of μM

Answer 1

Ksp of CuBr = 5.0 *10^-9

so, at saturation point, 5.0 * 10^-9 = [Cu⁺] x [Br^-]

if s is the molar concentration of each ion at saturation s² = 5.0 * 10^-9

s= (5.0 x 10^-9)^1/2

= 0.7071 x 10^-4

Therefore, saturated solution of CuBr would have bromide ion concentration = 7.071 x 10^-5

Ksp of AgBr = 4.1 x 10^-13

[Ag⁺] x [Br^-] = 4.1 x 10^-13

[Ag⁺] x7.071 x 10^-5 =   4.1 x 10^-13

The maximum concentration of silver ion = 4.1 x 10^-13 /7.071 x 10^-5

= 28.99 x 10^-8

= 2.899 x 10^-7 M

= 2.899 x 10^-4 mM

2.899 x 10^-4 mM beyond which the silver ion concentration precipitation of silver bromide starts.