Question

What is the final enthalpy of the solution made by mixing 5 grams of solution A having enthalpy 20 J with 15 grams of solution B having enthalpy 40 J?

(a) 10 J

(b) 20 J

(c) 25 J

(d) 35 J

I have been asked this question by my college director while I was bunking the class.

This question is 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 (d) 35 J

Explanation: Final enthalpy = 0.25*20 + 0.75*40 = 5 + 30 = 35 J.