Question

Which of the following reactions represents an exothermic reaction?

A. NH3(g) + 12.0 kcal → ½N2(g) + 3/2H2(g)
B. CH4 + 2O2 → CO2 + 2H2O + 212,800 cal
C. C + 2S → CS2, ΔH = 27,550 cal
D. C(graphite) → C(diamond), ΔH = 0.45 kcal
E. 2H2O → 2H2 + O2, ΔH = +58 kcal

Answer 1

B. CH4 + 2O2 → CO2 + 2H2O + 212,800 cal

Step-by-step explanation:

Exothermic means that energy is released.

A cannot be the answer since the process takes energy in at a surplus to work.

C and D have positive enthalpies, which indicate an endothermic reaction.