Calorimetry - Chemistry

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 4.30 L. The sample is ignited producing gas and releasing 609.7 J of energy. To what volume will the cylinder expand to if it must expand against a pressure of 846.1 mmHg. Assume all the energy released is converted to work used to push the piston? 

Answer 1

work = w = -P∆V

P = pressure = 846.1 mm Hg x 1 atm / 760 mm Hg = 1.11 atm

w = -609.7 J (negative sign because system is doing work)

-609.7 J = -(1.11 atm)(∆V)

-609.7 J x 1 Latm / 101.325 J = -6.017 Latm (converted joules to liter-atm)

6.017 Latm = -1.11 atm x ∆V L

∆V = -6.017 Latm / -1.11 atm = 5.42 L

New volume = 4.30 L + 5.42 L = 9.72 L