Answer:
1056.8 kJ
Explanation:
A sample of gas in a cylinder is provided with 623.9 kJ of heat. By convention, when the gas absorbs heat, it takes a positive sign, so Q = 623.9 kJ.
A piston then compresses the gas by doing 432.9 kJ of work to the gas. We work is done on the gas, it takes a positive sign, so W = 432.9 kJ.
The change in the internal energy (ΔU) is:
ΔU = Q + W
ΔU = 623.9 kJ + 432.9 kJ = 1056.8 kJ
