A system gains 687 kJ of heat, resulting in a change in internal energy of the system equal to 156 kJ. How much work is done? 1. Work was done by the system.2. Work was done on the system.

w = -531 kJ

1. Work was done by the system.

Explanation:

Step 1: Given data

Step 2: Calculate the work done (w)

We will use the following expression.

ΔU° = q + w

w = ΔU° - q

w = 156 kJ - 687 kJ

w = -531 kJ

By convention, when w < 0, work is done by the system on the surroundings.