Thermal diffusivity

Mandelbroth

Can the thermal diffusivity of an ideal gas be given by [itex]\frac{\bar{\nu}^2}{3\gamma Z}[/itex], where [itex]\bar{\nu}[/itex] is the root-mean-square speed of the particles, γ is the adiabatic index of the gas, and Z is the collision frequency?

The units check out, but I'm unsure of whether or not it works.