Question

A sample of limestone is $20\%$ pure. Find the mass of $C{O}_2$ produced by decomposing $40\text{g}$ of that sample of limestone.

• A. $7.04\text{g}$
• B. $1.76\text{g}$
• C. $3.52\text{g}$
• D. $3\text{g}$

Answer 1

The correct option is C $3.52\text{g}$

$CaC{O}_3\to CaO+C{O}_2$
Mass of $20\%$ pure $CaC{O}_3=\frac{20}{100}\times 40\text{g}=8\text{g}$
Moles of $CaC{O}_3=\frac{\text{given mass}}{\text{molar mass}}=\frac{8}{100}=0.08$ moles
As per the reaction,
$1$ mole of $CaC{O}_3$ decomposes to give $1$ mole of $C{O}_2$ gas.
$0.08$ mole of $CaC{O}_3$ will give $0.08$ mole of $C{O}_2.$
Mass of $C{O}_2$ produced $=0.08\times 44=3.52\text{g}$