Calculate ΔU for a system that loses 475 kJ of heat and does 155 kJ of expansion work on the surroundings.
A)-630 kJ
B)-320 kJ
C)+630 kJ
D)+320 kJ

Question

Quizplus · Accepted Answer

The change in internal energy (ΔU) for a system can be calculated using the first law of thermodynamics, ΔU = q + w, where q is the heat exchanged with the surroundings, and w is the work done by the system. Given that the system loses 475 kJ of heat (q = -475 kJ, since heat is lost) and does 155 kJ of expansion work on the surroundings (w = -155 kJ, since work is done by the system), ΔU = -475 kJ + (-155 kJ) = -630 kJ.

Calculate ΔU for a System That Loses 475 KJ of Heat