A gas is compressed from an initial volume of 5.35 L to a final volume of 1.23 L by an external pressure of 1.00 atm. During the compression the gas releases 128 J of heat. Required:
What is the change in internal energy of the gas?

The change in internal energy is  

Explanation:

From the question we are told that

    The initial volume is  

        The final volume is  

     The value of the external pressure is  

      The energy released by the gas is  

The negative sign show that energy is released from the system

Generally  the workdone on the gas is mathematically represented as

substituting values

The change in internal energy is mathematically evaluated as

substituting values