What is the enthalpy change of a reaction at 30oC, if the enthalpy of reactant at 30oC and 25oC are 18 J and 15 J, and enthalpy of product at 30oC and 25oC are 10 J and 8 J, and the enthalpy change of reaction at 25oC is 45 J?

Correct Answer: 50 J
Heat of reaction = (18 – 15) + (10 – 8) + 45 = 50 J.