Q. When 10 g of methane is completely burnt in oxygen, the heat evolved is 560 kJ. What is the heat of combustion ($in\ kJ\ {mol}^{- 1}$) of methane?
A) $- 1120$
B) $- 968$
C) $- 896$
D) $- 560$
Explanation
(c)
$CH_{4} + 2O_{2} \rightarrow CO_{2} + 2H_{2}O$
The heat of combustion of 10 g $CH_{4}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = - 560\ kJ$
So, the heat of combustion of 16 g $CH_{4}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \frac{- 560}{10} \times 16$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = - 896$ kJ/mol
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.