Question

The Ksp of PbBr₂ is 6.60x10^-6.

A) What is the molar solubility of PbBr₂ in Pure water?

B) what is the molar solubility of PbBr₂ in .500M KBr solution?

C) what is the molar solubility of PbBr₂ in a .500M Pb(No₃)₂ Solution?

Answer 1

Answer –

We are given, Ksp of PbBr₂ = 6.60x10^-6

A) We need to calculate the molar solubility of PbBr₂ in Pure water

We know the solubility expression for PbBr₂

Ksp = [Pb²⁺(aq)] [Br^-]²

6.60x10^-6 = (x) (2*0.500)²

6.60x10^-6 = 4x³

x³ = 6.60x10^-6 /4

    = 1.65*10^-6

x = 0.0118 M

so molar solubility of PbBr₂ in Pure water is 0.0118 M

B) We are given, [KBr] = 0.500 M

We know, [K⁺] = [Br^‑] = 0.500 M

No we need to calculate the molar solubility of PbBr₂ in .500M KBr solution

We know the solubility expression for PbBr₂

Ksp = [Pb²⁺(aq)] [Br^-]²

6.60x10^-6 = (x) (0.500)²

6.60x10^-6 = x* 0.25

x = 6.60x10^-6 /0.25

x = 2.6*10^-6 M

C) We are given, [Pb(NO₃)₂] = 0.500 M

We know, [Pb²⁺] = [NO₃^-] = 0.500 M

No we need to calculate the molar solubility of PbBr₂ in .500M KBr solution

We know the solubility expression for PbBr₂

Ksp = [Pb²⁺(aq)] [Br^-]²

6.60x10^-6 = (0.500) (2x)²

6.60x10^-6 = 0.500*4x²

x = 6.60x10^-6 /0.500

4x² = 1.3*10^-5 M

x² = 3.3*10^-6 M

x = 0.00182 M

Answer 2

Ksp of PbBr2 = 6.60 x 10^-6

A)

PbBr2 ----------> Pb+2   +   2 Br-

                              S             2 S

Ksp = [Pb+2] [Br-]^2

6.60 x 10^-6 = 4 S^3

S = 0.0118 M

molar solubility = 0.0118 M

B)

PbBr2 ----------> Pb+2   +   2 Br-

                              S             0.500

Ksp = [Pb+2] [Br-]^2

6.60 x 10^-6 = S x (0.500)^2

S = 2.64 x 10^-5

molar solubility = 2.64 x 10^-5 M

C)

PbBr2 ----------> Pb+2   +   2 Br-

                             0.500       2 S

Ksp = [Pb+2] [Br-]^2

6.60 x 10^-6 = (0.500) x (2S)^2

S = 1.82 x 10^-3 M

molar solubility = 1.82 x 10^-3 M