The internal energy change in a system that has absorbed 2 kcals of heat and done 500J of work is:
Options
(a) 6400 J
(b) 5400 J
(c) 7900 J
(d) 8900 J
Correct Answer:
7900 J
Explanation:
According to first law of thermodynamics Q = ∆U + W
∆U = Q – W = 2 x 4.2 x 1000 – 500 = 8400 – 500 = 7900 J