Question

A closed system (gas molecules do not enter or leave the cylinder) consists of a cylinder containing a gas, which has an internal energy given by U = (5/2) n R T. The initial pressure and volume are P₀ and V₀, respectively. The pressure of the gas is doubled while the volume remains constant (A→B), then its volume is doubled while the pressure remains constant (B→C), then the pressure is halved while the volume remains constant (C→D), and finally the volume is halved while the pressure remains constant (D→A), returning the gas to its original state. \

P 2PF B „C PO A V V 2V

Part 1

Positive work is done by the gas during the phase (A→B, C→D, B→C, or D→A), and negative work is done by the gas (i.e., work is done on the gas) during the phase (A→B, C→D, B→C, or D→A).

Part 2

The temperature of the gas goes up during the phase or phases (pick all answers that are correct)

a. A→B

b. C→D

c. B→C

d. D→A

Part 3

The internal energy U of the gas goes down during the phase or phases (pick all answers that are correct)

a. C→D

b. A→B

c. B→C

d. D→A

Part 4

Heat is added to the gas during the phase or phases (pick all answers that are correct)

a. B→C

b. C→D

c. A→B

d. D→A

Part 5

The net work done by the gas during the full cycle A→B→C→D→A is

a. 4 P₀V₀

b. zero

c. P₀V₀

d. 2 P₀V₀

e. 3 P₀V₀

Part 6

The total heat added to the gas during the first two phases of the cycle, A→B→C, is

a. zero

b. (15/2) P₀V₀

c. 5 P₀V₀

d. (5/2) P₀V₀

e. 2 P₀V₀

f. 7 P₀V₀

g. (19/2) P₀V₀

Answer 1