Question

What is the average kinetic energy of the molecules in a gas at 273K?

Answer 1

The average kinetic energy of the molecules is 5.66 × 10⁻²¹ J.

According to Kinetic Molecular Theory, the average kinetic energy of gas molecules is a function only of temperature.

The formula is

`KE = 3/2kT`

where `T` is the Kelvin temperature and `k` is Boltzmann's constant.

`KE = 3/2 × 1.381 × 10⁻²³ "J·K⁻¹" × 273"K"` = 5.66 × 10⁻²¹ J

For a mole of molecules, the average kinetic energy is

`(5.66 × 10⁻²¹"J")/(1"molecule") × (6.022 × 10²³"molecules")/(1"mol")` = 3.41 ×10³ J/mol = 3.41 kJ/mol