Question

The gas in a piston (defined as the system) warms and absorbs 650 J of heat. The expansion performs 380 J of work on the surroundings.

What is the change in internal energy for the system?
Express your answer in joules to three significant figures.

Answer 1

Answer: To calculate the change in internal energy for the system, we can use the First Law of Thermodynamics, which states:

ΔU = Q - W

Where:

ΔU = Change in internal energy of the system

Q = Heat added to the system (positive if heat is added, negative if heat is lost)

W = Work done by the system on the surroundings (positive if work is done on the surroundings, negative if work is done by the surroundings on the system)

Given:

Q = 650 J (heat absorbed by the system, positive because it is absorbed)

W = 380 J (work done by the system on the surroundings, positive because work is done on the surroundings)

Now, let's calculate the change in internal energy:

ΔU = 650 J - 380 J

ΔU = 270 J

The change in internal energy for the system is 270 J.