The pressure of an ideal gas of diatomic molecules is doubled by halving the volume.The ratio of the new internal energy to the old, both measured relative to the internal energy at 0 K, is:
A)1/4
B)1/2
C)1
D)2
E)4

Question

Quizplus · Accepted Answer

For an ideal diatomic gas, the internal energy is given by U = (5/2)nRT, where n is the number of moles, R is the gas constant, and T is the temperature. If the pressure is doubled by halving the volume, then the temperature must also double (P = nRT/V). Therefore, the new internal energy is U' = (5/2)nR(2T) = 2U. The ratio of the new internal energy to the old is U'/U = 2U/U = 2.

The Pressure of an Ideal Gas of Diatomic Molecules Is