Question

If Cp of water is (23 + T) J/^oC, what is the enthalpy change of water from 3^oC to 5^oC?

(a) 54 J

(b) 96 J

(c) 140 J

(d) 196 J

This question was posed to me during an interview.

Origin of the question is Phase Transitions in section Introduction to Energy Balances for Processes without Reaction and Calculation of Enthalpy Changes of Basic Chemical Engineering

Answer 1

Right option is (a) 54 J

For explanation I would say: ∆H = 3∫^5(23 + T).dT = 23(5 – 3) + (5^2 – 3^2)/2 = 54 J.