Question

The Ksp of PbBr2 is 6.60*10^-6

What is the molar solubility(M) of PbBr2 in pure water?

What is the molar solubility(M) of PbBr2 in 0.500M KBr solution?

What is the molar solubility(M) of PbBr2 in a 0.500M Pb(NO3)2 solution?

Answer 1

Concepts and reason

Solubility:

Solubility is defined as the maximum quantity of solute dissolved in a given amount of solvent to make a saturated solution at a particular temperature.

Molar solubility:

Molar solubility is the number of moles of a solute that can be dissolved in one liter of a solution. It is expressed as mol/L or M (molarity).

Common ion effect:

Common ion effect is defined as the solubility of a partially soluble salt which will decrease with the addition of a soluble salt that has an ion in common with it.

Fundamentals

Consider a general reaction:

The relation between solubility product and molar solubility is as follows:

Where,

Solubility product =

Molar solubility of M ion =

Molar solubility of X ion =

Therefore, the molar solubility (M) of in pure water is.

Therefore, the molar solubility (M) of in is.

Therefore, the molar solubility (M) of in is .

Ans:

The molar solubility (M) of in pure water is.

The molar solubility (M) of in is.

The molar solubility (M) of in is.

Answer 2

A. PbBr2 ---> Pb2+ + 2Br-
Ksp = 6.60 x 10^-6
Ksp = [Pb2+][Br-]^2
6.60 x 10^-6 = (x)(2x)^2
6.60 x 10^-6 = 4x^3
1.65 x 10^-6 = x^3
0.0118 M = x

B. PbBr2 ---> Pb2+ + 2Br-
Ksp = 6.60 x 10^-6
Ksp = [Pb2+][Br-]^2
6.60 x 10^-6 = (x)(0.500)^2
6.60 x 10^-6 = 0.25x
2.64 x 10^-5 M = x

C. PbBr2 ---> Pb2+ + 2Br-
Ksp = 6.60 x 10^-6
Ksp = [Pb2+][Br-]^2
6.60 x 10^-6 = (0.500)(2x)^2
6.60 x 10^-6 = (0.500)(4x^2)
6.60 x 10^-6 = 2x^2
3.3 x 10^-6 = x^2
0.00182 M = x