I am confused on the steps.

Question

A sample of flammable liquid is placed into an enclosed cylinder which is then fitted with a movable piston. Initially the cylinder contains a volume of 8.20 L. The sample is ignited producing gas and releasing 427.8 J of energy. To what volume will the cylinder expand to if it must expand against a pressure of 826.1 mmHg. Assume all the energy released is converted to work used to push the piston? 760 mmHg = 1 atm

101.3 J = 1 L atm

Answer 1

If all the heat goes into the work of expanding the gas at constant pressure, the work done is p(V2 - V1).

Let's convert the external pressure to atmospheres 826.1mm / 760 mm = 1.087 atm.

We are given that 101.3 j = 1 L-atm, so the heat produced 427.8 j x 1L-atm /101.3 j = 4.223 L-atm.

Putting this into the first equation 4.223 L-atm = 1.087 atm (V2 L - 8.2 L) and solve for V2.

V2 = 12.08 L