The mole

10.0 g of impure calcium carbonate sample contains only $CaCO_3$ and an inert impurity. On heating, the $CaCO_3$ decomposes completely:

$CaCO_3 \rightarrow CaO + CO_2$.

If 2.2 g of $CO_2$ is released, what is the percentage purity of $CaCO_3$ in the sample?