Question

Which has maximum solubility $AB,A{B}_2,A{B}_3,A{B}_4$ if $K_{sp}$ for all the salts are ${10}^{-10}$?

• A. $AB$
• B. $A{B}_2$
• C. $A{B}_3$
• D. $A{B}_4$

Answer 1

Answer: (D)

$A{B}_4$

$AB\rightleftharpoons A^{+}+B^{-}$

$K_{sp}=\left[A^{+}\right]\left[B^{-}\right]=\left(S\right)\left(S\right)=S^2$

$A{B}_2\rightleftharpoons A^{+}+2B^{-}$

$K_{sp}=\left[A^{+}\right][B^{-}{]}^2=(S\left)\right(2S{)}^2=4S^3$

$A{B}_3\rightleftharpoons A^{+}+3B^{-}$

$K_{sp}=\left[A^{+}\right][B^{-}{]}^3=(S\left)\right(3S{)}^3=27S^4$

$AB\rightleftharpoons A^{+}+4B^{-}$

$K_{sp}=\left[A^{+}\right][B^{-}{]}^4=(S\left)\right(4S{)}^4=256S^5$

So $A{B}_4$ has maximum solubility.