Limestone is mostly calcium carbonate,

CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance

Problem

\text{CaCO}_3

, but it also contains other minerals. When heated,

\text{CaCO}_3

decomposes into

\text{CaO}

and

\text{CO}_2

. A sample of

1.605\text{ g}

of limestone was heated and gave off

0.657\text{ g}

\text{CO}_2

. (1) Formulate the equation for the thermal decomposition of calcium carbonate. (2) Determine the percentage mass of

\text{CaCO}_3

in the limestone. (3) State the assumptions you are making in this calculation.