Question

Two gases A and B are placed in container that has a piston. A and B react to form product C. As the reaction occurs, the system loses 1450 J heat to the surrounding. The gas expands and the piston moves upward and the system does 1080 J work. Calculate the change in the internal energy.

Answer 1

By the first law of thermodynamics, we have:

ΔU = Q - W

where ΔU is the change in internal energy, Q is the heat transferred, and W is the work done.

In this problem, Q = -1450 J (heat is lost by the system) and W = 1080 J (work is done by the system). Therefore:

ΔU = -1450 J - 1080 J
ΔU = -2530 J

The change in internal energy is -2530 J.