2500 cc of oxygen was burnt with 600 cc of ethane [C2H6]. Calculate the volume of unused oxygen and the volume of carbon dioxide formed.

[By Lussac’s law]

2C₆H₆      +     7O₂    →    4CO₂    +    6H₂O

2 vol          :     7 vol   →   4 vol      :     6 vol

To calculate the volume of unused oxygen.

C₆H₆      :    O₂

2             :    7

600        :    x

⇒ x = 600 × 7\over 2

⇒ x = 2100 cc

Therefore, volume of unused oxygen = 2500 – 2100 = 400 cc

To calculate the volume of carbon dioxide formed

C₆H₆    :    CO₂

2           :     4

600      :     x

⇒ x = 600 × 4\over 2 = 1200 cc

Therefore, volume of carbon dioxide formed is 1200 cc