Question

When fuel is burned in a cylinder equipped with a piston, the volume expands from 0.245 L to 1.280 L against an external pressure of 1.02 atm . In addition, 843 J is emitted as heat. What is ΔE for the burning of the fuel?

Answer 1

`-949.97\ \text{J}`

Step-by-step explanation:

`P` = Pressure =
`1.02\ \text{atm}`

`dv` = Change in volume =
`(1.28-0.245)\ \text{L}`

`q` = Emission of heat =
`843\ \text{J}`

Work done is given by

`W=-Pdv\\\Rightarrow W=-1.02(1.28-0.245)* 10^(-3)* 101325\\\Rightarrow W=-106.97\ \text{J}`

Total energy of the system

`E=W+q\\\Rightarrow E=-106.97-843\\\Rightarrow E=-949.97\ \text{J}`

The
`\Delta E` for the burning of the fuel is
`-949.97\ \text{J}`.