The initial state of a mole of perfect gas is characterized by Po = 2.105 Pa, VO = 14 liters. This gas is successively subjected to the following reversible transformations:

• An isobaric relaxation that doubles its volume, transformation: (0→1).

• An isothermal compression that brings it back to its initial volume, transformation

: (1→2).

• An isochoric cooling that brings it back to its initial state, transformation:

(2→0).

1. Represent the pace of this cycle of transformations in the diagram (P in ordinates, V in abscissa). Arbitrary scale.

2. At what temperature is the isothermal compression carried out? Deduce the maximum pressure reached.

3. Calculate the work

W01,W12, W20 and heat quantities Q01,

Q12 and Q20 exchanged by the system during the cycle, depending on Po, Vo and

Y= Cp/Cv=1.4 (assumed constant in the temperature range studied).

4. Check that AU = 0 for the cycle.