1250 cc of oxygen was burnt with 300 cc of ethane [C₂H₆]. Calculate the volume of unused oxygen and the volume of carbon dioxide formed:

2C₂H₆ + 7O₂ ⟶ 4CO₂ + 6H₂O

$\begin{matrix} 2\text{C}$2\text{H}6 & + & 7\text{O}2 & \longrightarrow & 4\text{CO}2 & + & 6\text{H}_2\text{O} \\ 2 \text{ vol.} & : & 7 \text{ vol.} & \longrightarrow & 4 \text{ vol.} & \\ \end{matrix}

[By Gay Lussac's law]

2 Vol. of C₂H₆ requires 7 Vol. of oxygen

∴ 300 cc C₂H₆ will require $\dfrac{7}{2}$ x 300

= 1050 cc of Oxygen

Hence, unused oxygen = 1250 - 1050 = 200 cc

Similarly,

2 Vol. of C₂H₆ produces 4 Vol. of carbon dioxide

∴ 300 cc C₂H₆ produces $\dfrac{4}{2}$ x 300

= 600 cc of Carbon dioxide

Hence, carbon dioxide produced = 600 cc.