Question

What is the enthalpy change of the mixture if the enthalpy change of air is 10 J, enthalpy change of water vapor is 15 J, and the humidity is 40%?

(a) 10 J

(b) 12 J

(c) 14 J

(d) 16 J

I got this question in an interview.

The origin of the question is Applications of Humidity Chart in portion Humidity Charts & their Use, Analysis of the Degrees of Freedom in a Steady – State Process, Solving Material and Energy Balances Using Process and Unsteady State Material and Energy Balances of Basic Chemical Engineering

Answer 1

Correct answer is (d) 16 J

To explain I would say: ∆H = ∆Hair + ∆Hwater(h) = 10 + 15*0.4 = 16 J.