Calculating Expansion Work

We limit our discussion to calculation of the amout of work involved when a system expands or contracts against a constant pressure.

Calculating the Amount of Expansion Work at Constant Pressure Associated With a Volume Change

  1. Determine deltaV, the change in volume in cubic meters, m3, using the equation:

    Equation for calculating delta V

    Note: It may be necessary to convert the volumes to cubic meters.

  2. Determine P, the restraining pressure in Pascals.

  3. Calculate the work involved using the equation:

    Equation for calculating expansion work

    Note: If the pressure has units of Pascals and the volume units of m3, the work will have units of Joules. Work done by a system (as the system expands) has a negative value. Work done on a system (as the system shrinks) has a positive value.