Question

Solubility product constant of salts of types mx mx to end m3x at temperature t r 4.0 into 10 to the power minus 8 3.2 into 10 to the power minus 14 and 2.7 into 10 to the power minus 15 respectively solubility of the salt at temperature are in the order

Answer 1

For salt MX:

MX → M+ +X-

Ksp = [M+][X-]

Here [M+] = [X-]

So, Ksp =[M+]2

or

[M+] =[X-] =√Ksp = √(4.0×10-8) = 2×10-4

For salt MX2:

MX2 → M+ +2X-

Ksp = [M+][X-]2

Here 2[M+] = [X-]

So, Ksp =4[M+]3

or

[M+] =?Ksp/4 = ? [(3.2×10-14 )/4] = 2×10-5

For salt M3X,

M3X → 3M+ +X-

Ksp = [M+]3[X-]

Here [M+] = 3[X-]

So, Ksp =27[X-]4

or

[X-]4 = Ksp/27 =(2.7×10-15)/27

or

[X-] = 10-4

So, order of the solubilies is

MX  >M3X> MX2

Hence, the correct option is D.

Answer 2

For salt MX:

MX → M+ +X-

Ksp = [M+][X-]

Here [M+] = [X-]

So, Ksp =[M+]2

or

[M+] =[X-] =√Ksp = √(4.0×10-8) = 2×10-4

For salt MX2:

MX2 → M+ +2X-

Ksp = [M+][X-]2

Here 2[M+] = [X-]

So, Ksp =4[M+]3

or

[M+] =?Ksp/4 = ? [(3.2×10-14 )/4] = 2×10-5

For salt M3X,

M3X → 3M+ +X-

Ksp = [M+]3[X-]

Here [M+] = 3[X-]

So, Ksp =27[X-]4

or

[X-]4 = Ksp/27 =(2.7×10-15)/27

or

[X-] = 10-4

So, order of the solubilies is

MX  >M3X> MX2

Hence, the correct option is D.