Question

Define solubility product constant and derive the relationships between solubility

and solubility product constants for salts of AB2, A2B types.

Answer 1

Solution.

1.

$AB2 = A^{2+} + 2B^-$

$C(AB2) = Solubility = X$

$[A^{2+}] = X$

$[B^-] = 2 \times X$

$Ks = [A^{2+}] \times [B^-]^2 = X \times (2\times X)^2 = 4 \times X^3$

2.

$A2B = 2A^+ + B^{2-}$

$C(A2B) = Solubility = X$

$[A^+] = 2 \times X$

$[B^{2-}] = X$

$Ks = [A^+]^2 \times [B^{2-}] = (2 \times X)^2 \times X = 4 \times X^3$

Answer:

1.

$[A^{2+}] = X$

$[B^-] = 2 \times X$

$Ks = [A^{2+}] \times [B^-]^2 = X \times (2\times X)^2 = 4 \times X^3$

2.

$[A^+] = 2 \times X$

$[B^{2-}] = X$

$Ks = [A^+]^2 \times [B^{2-}] = (2 \times X)^2 \times X = 4 \times X^3$