What is the average kinetic energy Kavg of the hydrogen molecules at a temperature of 100K? Assume that the molecules have only three degrees of freedom at this temperature. Express your answer in joules to two significant figures.

207 x 10⁻²³ J

Explanation:

Average kinetic energy per degree of freedom = 1 / 2 k T

where k is Boltzmann constant and T is absolute temperature

The value of k is 1.38 x 10⁻²³

T given is 100 k

Average kinetic energy of a single degree of freedom

=.5 x 1.38 x 10⁻²³ x 100

= 69 x 10⁻²³

For 3 degree of freedom

Average energy = 3 x 69 x 10⁻²³

207 x 10⁻²³ J