Question

Consider a mixture of air and gasoline vapor in a cylinder with a piston. The original volume is 40. cm3. If the combustion of this mixture releases 912 J of energy, to what volume will the gases expand against a constant pressure of 635 torr if all the energy of combustion is converted into work to push back the piston?

Answer 1

The gases will expand until a volume of Vf= 10812 cm^3

Step-by-step explanation:

Since the gas mixture is expanding at constant pressure

`W=\int\limits^(Vf)_(Vi) {P} \, dV =P(Vf-Vi)`

and therefore

`Vf=W/P+Vi`

knowing that 1 torr=133,32 Pa

`p=635 torr * 133,322 Pa/torr * 1m^(3)/10^(6)cm^(3)=0,08466 J/ cm^(3)`

therefore

`Vf=912 J/(0,08466 J/cm^(3)) +40cm^(3) =10812 cm^(3)`