What volume of oxygen at STP is required to affect the combustion of 11 litres of ethylene [C₂H₄] at 273°C and 380 mm of Hg pressure?

C₂H₄ + 3O₂ ⟶ 2CO₂ + 2H₂O

$\begin{matrix} \text{C}$2\text{H}4 & + & 3\text{O}2 & \longrightarrow & 2\text{CO}2 + 2\text{H}_2\text{O} \\ 1 \text{ vol.} & : & 3 \text{ vol.} \\ 11 \text{ lit} & : & 33 \text{ lit} \end{matrix}

Using the gas equation,

$\dfrac{P${1}V{1}}{T{1}} = \dfrac{P{2}V{2}}{T{2}}

Substituting the values we get,

$\dfrac{760 \times x}{273} = \dfrac{380 \times 33}{546} \\[0.5em] x = \dfrac{380 \times 33 \times 273}{546 \times 760 } \\[0.5em] x = \dfrac{3,423,420}{414,960} \\ \\[0.5em] x = 8.25 \text{ lit}$

Hence, volume of oxygen required = 8.25 lit.