Question

A vertical, piston-cylinder device containing a gas is allowed to expand from 1 m3 to 3 m3. The heat added to the system during the constant pressure expansion was 200 kJ and the decrease in the energy of the system is 340 kJ. Calculate the gas pressure, in kPa.

Answer 1

Step-by-step explanation:

Given

Initial Volume
`v_1=1\ m^3`

final Volume
`v_2=3\ m^3`

Heat added at constant Pressure
`Q=200\ kJ`

Decrease in Energy of System
`\Delta U=-340\ kJ`

According to First law of thermodynamics

`Q=\Delta U+W`

`W=Q-\Delta U`

`W=200-(-340)`

`W=540\ kJ`

Work done in a constant Pressure Process is given by

`W=P\Delta V`

where P is the constant Pressure

`540=P* (3-1)`

`P=270\ kPa`