ideal-gas-problems

1. Ideal Gas
S.Gunabalan
Associate Professor
Mechanical Engineering Department
Bharathiyar College of Engineering & Technology
Karaikal - 609 609.
e-Mail : gunabalans@yahoo.com
Part - 2

2. Ideal Gas Equation of state

3. Ideal Gas Equation of state

4. Ideal Gas Equation of state

5. Ideal Gas Equation of state

6. Ideal Gas Equation of state

7. Units of Pressure
• atmospheric pressure (1 Atm.)
= 1.013 bar,
= 101325 Pascal (Pa = N/m²);
= 760 millimeters of mercury absolute
(mmHgA)
= 760 Torr (1 Torr = 1 mm HgA)

8. Gas Constant R
Gas Molar Weight ( M)Kg/Kmol Gas Constant (R )KJ/KgK
Air 28.97 0.287
Nitrogen 28.01 0.297
Oxygen 32 0.260
Hydrogen 2.016 4.124
Helium 4.004 2.077
Carbon dioxide 44.01 0.189
Steam 18.02 0.461

9. The specific volume of a substance is the ratio of
the substance's volume to its mass. It is the
reciprocal of density and is an intrinsic property
of matter.
Substance Name Density Specific Volume
Kg/m3 m3/Kg
Air 1.2 0.83
Ice 916.7 0.00109
Water (liquid) 1000 0.00100
Salt Water 1030 0.00097
Mercury 13546 0.00007

10. Note: Molar volume

11. Specific heat

12. Specific heat
• The specific heat - the amount of heat required
to raise a unit mass of the substance through a
unit rise in temperature.
• The product of mass and specific heat (mCv) is
called the heat capacity(Cv) at constant volume
(J/K)
• The latent heat is the amount of heat transfer
required to cause a phase change in unit mass of
a substance at a constant pressure and
temperature

13. Questions -1

14. Gas Molar Weight ( M)Kg/Kmol
Air 28.97
Nitrogen 28.01

19. Gas Molar Weight ( M)Kg/Kmol
Air 28.97
Nitrogen 28.01
J = Nm

25. When work is done by a system, it is arbitrarily
taken to be positive, and
when work is done on a system, taken to be
negative

27. Exercise-1

28. Question-2

29. Procedure

30. Procedure

31. Given data
V = 60 liters of CO2
P = 10 bar
T = 20 °C
atmospheric pressure (1 Atm.)
1 Atm = 1.013 bar,
1 Atm = 101325 Pascal (Pa = N/m²);
Unit conversion
1 bar = 1x 105 N/m2
1 m3 = 1000 liters
J = Nm

32. Given data
V = 60 liters of CO2
P = 10 bar
T = 20 °C
Gas Molar Weight (
M)
Kg/Kmol
Gas Constant
(R) KJ/KgK
Air 28.97 0.287
Nitrogen 28.01 0.297
Oxygen 32 0.260
Hydrogen 2.016 4.124
Helium 4.004 2.077
Carbon dioxide 44.01 0.189
Steam 18.02 0.461
atmospheric pressure (1 Atm.)
1 Atm = 1.013 bar,
1 Atm = 101325 Pascal (Pa = N/m²);
Unit conversion
1 bar = 1x 105 N/m2
1 m3 = 1000 liters
J = Nm

33. Gas Molar Weight (
M)
Kg/Kmol
Gas Constant
(R) KJ/KgK
Air 28.97 0.287
Nitrogen 28.01 0.297
Oxygen 32 0.260
Hydrogen 2.016 4.124
Helium 4.004 2.077
Carbon dioxide 44.01 0.189
Steam 18.02 0.461
atmospheric pressure (1 Atm.)
1 Atm = 1.013 bar,
1 Atm = 101325 Pascal (Pa = N/m²);
Unit conversion
1 bar = 1x 105 N/m2
1 m3 = 1000 liters
J = Nm

34. Gas Molar Weight (
M)
Kg/Kmol
Gas Constant
(R) KJ/KgK
Air 28.97 0.287
Helium 4.004 2.077
Carbon dioxide 44.01 0.189
Steam 18.02 0.461
P = 10 bar = 10 x 105 N/m2
V = 60 liters = 60/1000 m3
⤫M = find
⤫R = cal for the substitution
T = 20 °C = 20 +273 K

35. Given data
V = 60 liters of CO2
P = 10 bar
T = 20 °C

36. Given data
V = 60 liters of CO2
P = 10 bar
T = 20 °C

37. Exercise -2
Find the molecular weight and gas constant for
the gas, whose specific heats are as follows
Cp = 1.967 KJ/Kg K
Cv = 1.507 KJ/Kg K

38. Exercise -2

39. Reference
• Rajput, R. K. 2010. Engineering thermodynamics. Jones and Bartlett
Publishers, Sudbury, Mass.
• Singh, O. 2003. Applied thermodynamics. New Age International (P) Ltd.,
Publishers, New Delhi.
• Nag, P. K. 2002. Basic and applied thermodynamics. Tata McGraw-Hill, New
Delhi.