The gas is first cooled at constant volume until it reaches its final pressure.

Question

The gas is first cooled at constant volume until it reaches its final pressure. It is then allowed to expand at constant pressure until it reaches its final volume. (Use the following as necessary: P1 = 2.90 atm, V1 = 1.20 L, and Eint 1 = 451 J and its final state P2 = 1.90 atm, V2 = 2.90 L, and Eint 2 = 914 J.)

(a) Illustrate this process on a PV diagram (Do this on paper. Your instructor may ask you to turn in this work.) What is the work done by the gas.
  J

(b) Find the heat absorbed by the gas during this process.
  J

Explanation / Answer

A)

The PV diagram is seen in the figure to the right. Because there is no work done on the constant volume part, the net work done is just from the isothermal part

which is W = nRTi ln ( Vf/ Vi)

, where Ti is the initial temperature.

Plugging in the values, and replacing nRTi = PiVi , using the ideal gas law, gives

=PiVi (ln Vf/ VI)

=2.9*1.2ln(2.9/1.2)

=3.07*102

=307J

B)

Remember the first law of thermodynamics, ?Ein = Q + W, and so

Q = ?E ? W = (914? 451) + 307 = 770 Joules.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.