An ideal gas, expanding at a constant pressure from 50 cm3 to 150 cm3, did the work of 300 J

An ideal gas, expanding at a constant pressure from 50 cm3 to 150 cm3, did the work of 300 J. What pressure was the gas at? How has his internal energy changed?

According to the formula, the work of gas is equal to:

A = p * (V2 – V1).

Therefore, the pressure can be expressed:

p = A / (V2 – V1) = 300 J / (150 cm ^ 3 – 50 cm ^ 3) = 3,000,000 Pa.

Since when the volume changes, the distance between the molecules changes, the internal energy also changes:
Uin = 3/2 * n * R * ΔT = 3/2 * p * (V2 – V1) = 3/2 * A.

Therefore, we substitute the existing values of the work done by the gas into the formula:

Uvn = 3/2 * 300 J = 450 J.

Answer: the gas pressure is 3,000,000 Pa, and the energy change is 450 J.