Rosmiza Mokhtar ESM Dept, COE, Uniten
Exercise Chapter 21 : The Kinetic Theory of Gasses
1. A 2 moles Cl2 gas of volume 5 liters undergoes an isobaric process at 2 atm so that its temperature
rises by 50oC. It then undergoes an isovolumetric process gaining 400J of heat. Find
i)
the work done during the isobaric process [831.4 J]
ii)
the change in internal energy of the isobaric process [2078.5 J]
iii)
the heat enters the gas during the isobaric process [2909.9 J]
iv)
the final temperature of the gas during the isovolumetric process [120.52 K]
[R = 8.314 Nm/mol K, 1 atm =
1.013  10 5 Pa]
2005/2006
2. (a) One mole of oxygen (  = 7/5) initially at temperature T = 290 K is compressed adiabatically so
that its pressure rises 10 times. Find the final temperature of the gas. [560 K]
(b) (i) What is the kinetic energy of a gas molecule if it is heated to 100oC? [7.72  10-21 J]
(ii) What is the total translational energy possessed by 6 mole of monatomic gas at 100oC?
[2.792  104 J]
2006/2007
3. (a) A 6.00-L container contains helium gas at 30.0oC and 2.00 atm.
(i)
Find the total translational kinetic energy of the gas molecules. [1818 J]
(ii)
Find the average kinetic energy per molecule. [6.27  10-21 J]
(b) How much work is required to compress 3.00 mol of air at 25.0oC and 1.00 atm to one tenth of
the original volume by an isothermal process? [- 1.71  104 J]
(c) An air is at 30.0oC in the cylinder of an engine. It is compressed from initial pressure of 0.500
atm and volume of 1000 cm3 to a volume of 50.0 cm 3. Assume that the air behaves as an ideal
gas with  = 1.4 and that the compression is adiabatic. Find
(i)
the final pressure and [33.14 atm]
(ii)
the final temperature of the air [1004.3 K]
2007/2008
4.One mole of an ideal monatomic gas is at an initial temperature of 300 K. The gas undergoes an
isovolumetric process, acquiring 500 J of energy by heat. It then undergoes an isobaric process,
losing this same amount of energy by heat. Determine (a) the new temperature of the gas [316 K]
and (b) the work done on the gas. [200 J]
Textbook
10. (a) Figure 1 shows a cycle consisting of five paths : AB and DE are isothermal at the temperature
of 300K and 100K respectively. BC is adiabatic with work of 5.00 J, EA is adiabatic with a
change in internal energy of 8.00 J.
(i) What is the change in internal energy of the gas along path CD (isobaric)? [- 3 J]
(ii) What is the work done on the gas along path AB if the work done by path CE is +10.0 J
and the total work done of the gas for the whole process is +9 J? [2 J]
Final 2007/2008
1
Rosmiza Mokhtar ESM Dept, COE, Uniten
P
A
B
E
C
D
V
11. (a) A gas is compressed isothermally at 300 K from an initial volume of 0.5 liter (at 1.0 atm
pressure) to a final volume of 0.25 liter. What is the work done by the gas during this
compression? [- 35.1 J]
(b) A diatomic gas (  = 1.40) in an engine is initially at 300 K, a pressure of 1.0 atm and occupies
a volume of 900 cm3. The gas is compressed adiabatically by a piston in a cylinder to 10% of
its initial volume.
i)
Find the final pressure of the gas. [2.54  106 Pa]
ii)
Find the final temperature of the gas. [753 K]
iii)
What is the work done by the gas? [- 343.7 J]
Final 2006/2007
5. The air in an automobile engine at 20oC is compressed from an initial pressure of 1 atm and a
volume of 200 cm3 to a volume of 20 cm3. Find the temperature if the air behaves like an ideal gas
(  = 1.4) and the compression is adiabatic. [736 K or 463oC]
6. During an adiabatic compression a volume of air decreases to 1 its original size. Calculate its final
4
pressure if its original pressure was 1 atm (Assume the air behaves like an ideal gas with
[6.9 atm]

= 1.4)
7. An ideal gas is allowed to expand adiabatically until its volume increases by 50%. By
approximately what factor is the pressure reduced? (  = 1.67) [2]
8. One mole of helium gas expands adiabatically from 2 atm pressure to 1 atm pressure. If the original
temperature of the gas is 20oC, what is the final temperature of the gas? (  = 1.67) [222 K]
9. Air expands adiabatically (no heat in, no heat out) from T = 300K and P = 100 atm to a final
pressure of 1 atm. Treat the gas as ideal with
[80.5 K]

= 1.4, and determine the final temperature.
2