Question

14. The total internal energy change for a gas is -1500. J. If it expanded from 1.000 liters to 5.000 liters against a pressure of 1.500 atm, what was the change in heat for the system? (1.00 L'atm = 101.0 J) 1) +1506 J 2) -1506.J 3) -2106. J 4) +2106.J

FYI, the answer is not in the answer choice. Instead, it is -894J but I do not know how to solve the problem

Answer 1

According to first law of thermodynamics ,

ΔU = ∆q+w

Where,

ΔU = total change in internal energy of a system = - 1500 J
∆ q = change in heat between a system and its surroundings
w = work done by or on the system = - p∆V

Where p = 1.500 atm

∆V = change in volume = 5.000 - 1.000 L = 4.000 L

Substitute the values,

- 1500 J = ∆q + ( - 1.500 atm × 4.000 L)

- 1500 J = ∆q + ( - 1.5000 × 4.000 × (101.0 J))

∆ q = -1500 J + 606 J

∆ q = - 894 J