Quiz — Application to the Ideal Gas

Question 1

An ideal gas undergoes a Joule expansion: the partition separating it from an empty compartment is broken inside an insulated enclosure. Its final temperature is:

Accepted Answer

Unchanged

Question 2

One mole of ideal gas undergoes an isothermal compression. What is ΔU?

Accepted Answer

ΔU = 0

Question 3

An ideal gas undergoes a quasi-static isothermal expansion. Which energy balance is correct?

Accepted Answer

W < 0, Q > 0 and ΔU = 0: the gas does work and receives heat

Question 4

Starting from the same state (P,V), an ideal gas is expanded quasi-statically either isothermally or adiabatically. Which statement is correct?

Accepted Answer

The adiabat is steeper than the isotherm in the (P,V) diagram, the pressure drops faster, and the gas cools

Question 5

In a Clapeyron (P,V) diagram, an ideal gas follows a clockwise cycle. With energy received by the gas taken as positive, how is the cycle classified and what are the signs of the net transfers?

Accepted Answer

Power cycle: W_cycle < 0 and Q_cycle > 0

Question 6

During an adiabatic process of an ideal gas, Q = 0; its temperature must therefore remain constant.

Accepted Answer

False

Question 7

Two equal amounts of an ideal gas, initially at the same temperature, receive the same heat Q > 0. The first is heated at constant volume and the second at constant pressure. Which reaches the higher final temperature?

Accepted Answer

The gas heated at constant volume, because c_V < c_P

Question 8

An ideal gas goes from state A to state B with P_B = P_A/2 and V_B = 3V_A. What can be stated without knowing the path?

Accepted Answer

The gas heats up, but the signs of Q and W cannot be determined separately

Question 9

In a (P,V) diagram, states C(2P_0,V_0) and B(P_0,2V_0) are joined by a straight line segment. What can be stated for an ideal gas?

Accepted Answer

ΔU_{C→B} = 0, but the process is not isothermal and Q_{C→B} = -W_{C→B}