Question

Consider these compounds:

A. Mg(OH)₂

B. BaSO₄

C. Zn(OH)₂

D. CaCO₃

Complete the following statements by entering the letter corresponding to the correct compound.

Without doing any calculations it is possible to determine that manganese(II) hydroxide is more soluble than _____ , and manganese(II) hydroxide is less soluble than _____.

It is not possible to determine whether manganese(II) hydroxide is more or less soluble than _______ by simply comparing K_sp values.

Answer 1

We can only compare

Mn(OH)2 --> AB2 type

which is Zn(OH)2 only

therefore

we can only use Ksp to compare solubility with Zn(OH)2

for BaSO4 and CaCO3 , we will need to perform calcualtion of Solubility:

For instnace:

For solubility comparisson:

AB <-> A+ + B-; Ksp = [A+][B-] = S*S = S^2 --> S = sqrt(Ksp)

A2B <--> 2A+ + B-2 Ksp = [A+]^2[B-2] = (2S)^2 * S = 4*S^3 --> S = (Ksp/4)^(1/3)

AB2 <--> A+2 + 2B- ; Ksp = [A+2][B-]^2 = S* (2S)^2 = 4*S^3 --> S = (Ksp/4)^(1/3)