Question

An ideal gas in a piston is placed in a refrigerator, which removes 413 J of energy from the gas via cooling. The plunger on the piston is pushed down, which does 70 J of work on the gas.

1)

What is the net change in the internal energy of the gas in the piston?

Answer 1

The net change in the internal energy of the gas in the piston is -343J

Step-by-step explanation:

Because heat and workdone are the only means of energy transfer between the system and the surrounding, change in internal energy is given by;

∆E = q + w

q = heat transfer

w = workdone

Because heat is lost by the system, the heat transfer is negative

q = -413J

Because work is done on the system, workdone is positive

w = +70J

∆E = -413J + 70J

∆E = -343J