The p-V-T behavior of a mixture of ideal gases can also be based on Amagat’s
law
Amagat’s law of additive volumes: The volume of an ideal gas mixture is equal to the sum
of the volumes each gas would occupy if it existed alone at the mixture temperature and
pressure (Fig. 1.3)
Since both the mixture and each of its component obey the ideal gas equation of
state
pV ¼ NRT
p i V ¼ N i RT
where p i is the partial pressure of the ith component. It follows
p i
p
¼
N i
N
¼ x i
ð8Þ
Fig. 1.3 Amagat’s law and Dalton’s law
1.6 Mixtures of Ideal Gases
15