Question

$400m^3$ of acetylene is allowed to combust stoichiometrically in air. The volume of gaseous $\left(in{m}^3\right)$ products obtained after combustion is .
(It is give that air has 20% v/v $O_2$))

Answer 1

Balanced reaction for combustion of acetylene:
$\underset{\left(A\right)}{C_2{H}_2}+\underset{\left(B\right)}{\frac{5}{2}{O}_2}⟶\underset{\left(C\right)}{2C{O}_2}+\underset{\left(D\right)}{H_{2}O}$
Mole ratio of species, $A:B;C:D=1:2.5;2:1$
According to Avogadro's law, $n\propto V$
Volume ratio of species, $A:B;C:D=400m^3:1000m^3;800m^3:400m^3$
Since only 20 ml oxygen is present per 100 ml of air. So 80 ml of air is left unreacted per 20 ml of oxygen.
Air left when $1000m^3$ oxygen reacted $=1000\times \frac{80}{20}=4000m^3$
Total volume of gaseous product$4000+800+400=5200m^3$