Question

Can you please explain

A fuel-air mixture is placed in a cylinder fitted with a piston. The original volume is 0.290-L. When the mixture is ignited, gases are produced and 865 J of energy is released. To what volume will the gases expand against a constant pressure of 635 mmHg, if all the energy released is converted to work to push the piston?

Answer 1

Answer : The final volume of will be 10.5 liters.

Explanation :

Formula used :

`w=-p_(ext)dV\\\\w=-p_(ext)(V_2-V_1)`

where,

w = work done = -865 J = -8.54 L.atm

Conversion used : (1 L.atm = 101.3 J)

`p_(ext)` = external pressure = 635 mmHg = 0.836 atm

Conversion used : (760 mmHg = 1 atm)

`V_1` = initial volume of gas = 0.290 L

`V_2` = final volume of gas = ?

Now put all the given values in the above formula, we get :

`w=-p_(ext)(V_2-V_1)`

`-8.54L.atm=-(0.836atm)* (V_2-0.290)L`

`V_2=10.5L`

Therefore, the final volume of will be 10.5 liters.