Question

One litre of sturated solution of $CaC{O}_3$ is eveaporated to dryness, when $7.0g$ of residue is left. The solubility product for $CaC{O}_3$ is:-

• A. $4.9\times {10}^{-3}$
• B. $4.9\times {10}^{-5}$
• C. $4.9\times {10}^{-9}$
• D. $4.9\times {10}^{-7}$

Answer 1

Answer: (A)

$4.9\times {10}^{-3}$

$CaC{O}_3\to C{a}^{2+}+C{O}_3^{2-}$

The moles of $CaC{O}_3$ = $\frac{gram}{molarmass}=\frac{7}{100}=0.07$

Concentration = $\frac{0.07}{1lt}=0.07M$

The mole ratio of $CaC{O}_3$ and its ions is 1:1

The concentration of ions $[C{a}^{2+};C{O}_3^{2-}]$ = 0.07M

$K_{s}p=\left[C{a}^{2+}\right]\left[C{O}_3^{2-}\right]=(0.7{)}^2=0.0049=>4.9\ast {10}^{-3}$