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 1.60 L. The sample is ignited producing gas and releasing 401.5 J of energy. To what volume will the cylinder expand to if it must expand against a pressure of 729.8 mmHg. Assume all the energy released is converted to work used to push the piston?

Answer 1

Answer: The volume of the cylinder after expansion is 5.73 L

Explanation:

To calculate the amount of work done for an isothermal process is given by the equation:

$W=-P\Delta V=-P(V_2-V_1)$

W = amount of work done  = -401.5 J = -3.962 L.atm      (Conversion factor: 1 L atm = 101.325 J)

P = pressure  = 729.8 mmHg =  0.960 atm      (Conversion factor: 1 atm = 760 mmHg)

$V_1$ = initial volume = 1.60 L

$V_2$ = final volume = ?

Putting values in above equation, we get:

$-3.962L.atm=-0.960atm\times (V_2-1.60)L\\\\V_2=5.73L$

Hence, the volume of the cylinder after expansion is 5.73 L