Question

What is the heat of reaction for C6H6 + 3H2 -> C6H12, if heat of formation of C6H6, H2, and C6H12 are 25 J, 5 J and 50 J respectively?

(a) 10 J

(b) 20 J

(c) 30 J

(d) 35 J

This question was posed to me in an internship interview.

My doubt stems from Heat (Enthalpy) of Reaction in chapter Application of Energy Balances in the Absence of Chemical Reactions and Energy Balances: How to Account for Chemical Reaction of Basic Chemical Engineering

Answer 1

Right answer is (a) 10 J

The explanation is: Heat of reaction = 50 – 3*5 – 25 = 10 J.