Q. The enthalpy of combustion of methane at $25^{0}C$ is 890kJ. The heat liberated when 3.2 g of methane is burnt in air is
A) 445 kJ
B) 278 kJ
C) -890 kJ
D) 178 kJ
Explanation
(d)
The combustion of methane can be represented by the following equation
$CH_{4} + 2O_{2} \rightarrow CO_{2} + 2H_{2}O + 890\ kJ$
16 g
$\therefore$ 16 g $CH_{4}$ burns in air to liberate=890 kJ of heat
$\therefore$ 3.2 g $CH_{4}$ will liberate=$\frac{890 \times 3.2}{16}$
=178 kJ of heat
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.