Question

$3$ g of a hydrocarbon, on combustion in excess of oxygen, produces $8.8$ g of ${CO}_2$ and $5.4$ g of $H_{2}O$. The data illustrates the law of:

• A. conservation of mass
• B. multiple proportions
• C. constant proportions
• D. none of these

Answer 1

Answer: (A)

conservation of mass

Weight of ${CO}_2=8.8gm$

Moles of ${CO}_2=\frac{8.8}{44}=0.2$

Moles of $C=0.2$

Wt. of $C=0.2\times 12=2.4g$

Moles of $H_{2}O=\frac{5.4}{18}=0.3$

So, moles of $H$ atom $=0.3\times 2$

Wt. of hydrogen $=0.3\times 2\times 1=0.6$

Wt. of carbon + hydrogen $=2.4+0.6=3=$ Initial wt. of hydrocarbon

Hence, it illustrates the law of conservation of mass.