Question

What is the heat transferred from the system if the output sensible heat is 5 J, input sensible heat is 20 J, and heat of solution is 10 J?

(a) -10 J

(b) -5 J

(c) 0

(d) 10 J

This question was addressed to me in class test.

This intriguing question originated from Effects of Mixing into Energy Balance topic in portion Energy Balances that Include the Effects of Chemical Reaction, Ideal Processes, Efficiency and the Mechanical Energy Balance and Heats of Solution and Mixing of Basic Chemical Engineering

Answer 1

The correct answer is (b) -5 J

To explain: Q = ∆Hout,sensible – ∆Hin,sensible + ∆Hsolution = 5 – 20 + 10 = -5 J.