Question

What is the enthalpy change of a reaction at 35^oC, if the enthalpy of reactant at 35^oC and 25^oC are 22 J and 15 J, and enthalpy of product at 35^oC and 25^oC are 10 J and 5 J, and the enthalpy change of reaction at 25^oC is 36 J?

(a) 12 J

(b) 24 J

(c) 36 J

(d) 48 J

This question was addressed to me in a national level competition.

Query is from Heat (Enthalpy) of Reaction topic in division 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 (d) 48 J

To explain I would say: Heat of reaction = (22 – 15) + (10 – 5) + 36 = 7 + 5 + 36 = 48 J.