Question

A gas is compressed from an initial volume of 5.65 L to a final volume of 1.24 L by an external pressure of 1.00 atm. During the compression the gas releases 122 J of heat.

Answer 1

This is an incomplete question. The complete question is:

A gas is compressed from an initial volume of 5.50 L to a final volume of 1.20 L by an external pressure of 1.00 atm. During the compression the gas releases 128 J of heat. What is the change in internal energy of the gas?

Answer: 325 Joules

Explanation:

According to first law of thermodynamics:

$\Delta E=q+w$

$\Delta E$=Change in internal energy

q = heat absorbed or released

w = work done or by the system

w = work done on the system=$-P\Delta V$  {Work is done on the system as the final volume is lesser than initial volume and is positive}

w =$-1.00atm\times (1.24-5.65)L=4.41Latm=447Joules$  {1Latm=101.3J}

q = -122J   {Heat released by the system is negative}

$\Delta E=+447+(-122)=325J$

Thus the change in internal energy of the gas is 325 Joules