
16 The Principles of Thermodynamics
It is to be noted that these relations are valid for all thermodynamic systems whether
they are solids, liquids, or gases. Among gases they hold for ideal as well as non-
ideal gases. It is the existence of such very general relationships that makes thermo-
dynamics so powerful. For example, knowing
β
V
,
β
P
would immediately determine
κ
T
without a need for its independent determination.
Example 1.4: Work by ideal gases
Calculate the work done by an ideal gas for i) an isothermal expansion from volume
V
1
to V
2
at T; ii) an isothermal rarefaction from pressure P
1
to pressure P
2
at T; iii)
from volume V
1
to V
2
during an isobaric ...