Question

A gas mixture of 3.67 liter of ethylene and methane on complete combustion at 25°C produces 6.11 liter of CO₂ . Find out the heat evolved on burning 1 liter of the gas mixture. The heats of combustion of ethylene and methane are- 1423 and − 891 kJ mol⁻¹ at 25°C.

Answer 1

Given, 2a + 3.67 – a = 6.11; a = 2.44 liter 

Volume of ethylene in mixture = 2.44 liter 

Volume of ethylene in mixture = 1.23 liter 

Volume of ethylene in 1 liter mixture  

= 2.44/3.67 = 0.6649 liter

Volume of ethylene in 1 liter mixture

= 1.23/3.67 = 0.3351 liter

24.45 liter of gas at 25°C corresponds to 1 mole. 

Thus, heat evolved by burning 0.6649 liter of ethylene

= 1423/24.5 x 0.6649 =-38.69 kJ  

and heat evolved by burning 0.3351 liter of methane 

=−891/24.45 x 0.3351 = -12.21 kJ

So, total heat evolved by burning 1 liter mixture 

= - 38.68 – 12.21 = - 50.90 kJ