How many gms of $\mathrm{CaC}_{2} \mathrm{O}_{4}$ will dissolve in one litre of saturated solution.…

How many gms of $\mathrm{CaC}_{2} \mathrm{O}_{4}$ will dissolve in one litre of saturated solution. $\mathrm{K}_{\mathrm{sp}}$ of $\mathrm{CaC}_{2} \mathrm{O}_{4}$ is $2.5 \times 10^{-9} \mathrm{~mol}^{2} \mathrm{lit}^{-2}$
  1. $0.0064 \mathrm{~g}$
  2. $0.0128 \mathrm{~g}$
  3. $0.0032 \mathrm{~g}$
  4. None of these

Solution

$\mathrm{CaC}_{2} \mathrm{O}_{4} ightleftharpoons \mathrm{Ca}^{2+}+\mathrm{C}_{2} \mathrm{O}_{4}^{2-} ; \mathrm{K}_{\mathrm{sp}}=\mathrm{S}^{2}$
$\therefore \mathrm{S}=\sqrt{\mathrm{K}_{\mathrm{sp}}}=\sqrt{2.5 \times 10^{-9}}=5 \times 10^{-5} \mathrm{~mol} / \mathrm{litre}$
solubility $=5 \times 10^{-5} \times 128=0.0064 \mathrm{~g}$ .

Asked in: JEE-TOPICTESTS-CHEMISTRY

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