If 100g of calcium carbonate on heating produces 44g of carbon dioxide, how much quick lime will be formed? Which law follows from this example? Define the law.

Question

If 100g of calcium carbonate on heating produces 44g of
carbon dioxide, how much quick lime will be formed?
Which law follows from this example? Define the
law

Kirti Gogia · Accepted Answer

The chemical equation showing the thermal decomposition of CaCO₃ is written as follows :

$C a C O_{3} \overset{Δ}{\to} C a O + C O_{2}$

According to the above equation, one mole of CaCO₃ decomposes to give one mole of CaO and one mole of CO₂. The molar mass of CaCO₃ is 100 g while that of CaO and CO₂ is 56 g and 44 g respectively.

Therefore as per the given data, if 100g of CaCO₃ on decomposition gives 44 g of CO₂, then the mass of CaO obtained should be 56g. This is in accordance with the law of conservation of mass.

Law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. Hence the total mass of reactants should be equal to the mass of products. Therefore in the said reaction, the mass of CaCO₃ should be equal to the mass of total mass of products that is CaO and CO₂.