Q. Which one of the following is an exothermic reaction?
A) $N_{2}(g) + O_{2}(g) + 180.8kJ \rightarrow 2NO(g)$
B) $N_{2}(g) + 3H_{2}(g) - 92kJ \rightarrow 2NH_{3}(g)$
C) $C(g) + H_{2}O \rightarrow CO(g) + H_{2}(g) - 131.1kJ$
D) $C(graphite) + 2S(s) \rightarrow CS_{2}(l) - 91.9kJ$
Explanation
(b)
The reactions in which products has lesser energy than reactants, then energy is released in the reaction and such reactions are known as exothermic reactions e.g.,
$N_{2} + 3H_{2} \rightarrow 2NH_{3} + 92\ kJ$
In this equation energy is released, so, it is an example of exothermic reaction.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.