Consider an ionic solid that dissolves in water according to the equation:
`M_(n)X_(m(s)) nM_(aq)^(m+)n + mX_(aq)^(n-)` . The equilibrium constant for this reaction, `K _(sp)=[M^(m+)]^(n) [X^(n-)]^(m) ` is known as the solubility product of `M_(n), X_(m)`. The form of this euquilibrium is important in understanding effects such as the influence of pH, complex fomation and common ion cffect. Equilibrium constant in solution should be written correctly using activities and not concentrations. The difference between thesc quantities is large in concentrated ionic solutions and `K_(sp)` is quantitatively reliable as a guide of solubilities only for very dilute solutions, If solubility product of AB type salt is `4xx 10^(-10)` at `18^(@)`C, and M.W of AB is 143.5 g/mol.
The solubility in g/lit of AB is

Options

A. `14.35 gm// "lit"`
B. ` 2.87 xx 10^(-3) gm//"lit"`
C. ` 1.43 gm //"lit"`
D. ` 28.7 gm //"lit"`

Answer

B

Explanation

` AB hArr underset(S) A^(+) +underset( S )B^(-) , K_(sp) = S^(2) = 4 xx 10 ^(-10 ) `
` S = 2 xx 10 ^(-5) `
Weight ` = 2 xx 10 ^(-5) xx 143. 5 = 2.87 xx 10 ^(-3) g // lit `