Calculate Work Done by Ideal Gas

[notsam]

Homework Statement

1 mole of an ideal gas is at 9 atm pressure,
occupies 1 L and has an internal energy of
474 J. The gas is first cooled at constant
volume until its pressure is 1 atm. It is then
allowed to expand at constant pressure until
its volume is 7 L with an internal energy of
766 J.
Calculate the work done by the gas.
Answer in units of J.

Homework Equations

W=pv+p2v2

The Attempt at a Solution

So I'm thinking that the work will equal the preassure times the volume change plus the next preassure times the volume change to give me the total work in J. Yes?

 

[Andrew Mason]

Homework Statement

1 mole of an ideal gas is at 9 atm pressure,
occupies 1 L and has an internal energy of
474 J. The gas is first cooled at constant
volume until its pressure is 1 atm. It is then
allowed to expand at constant pressure until
its volume is 7 L with an internal energy of
766 J.
Calculate the work done by the gas.
Answer in units of J.

Since the expansion is at constant pressure, $W = P\Delta V$. Be careful in converting units (atm. must be converted to Pa or N/m; litres to m^3). You are given the change in volume and the pressure so it should not be difficult.

AM