External forces on the gas performed work of 300 J, while the internal energy of the gas increased by 400 J.

External forces on the gas performed work of 300 J, while the internal energy of the gas increased by 400 J. How much heat was transferred to the gas.

Given:
A = 300 J
ΔU = 400 J
Find: Q =?
Decision:
According to the first law of thermodynamics
ΔU = Q + A
Q = ΔU – A
Q = 400 J – 300 J = 100 J
Answer: Q = 100 J.