The gas used in separating the two uranium isotopes${}^{\mathbf{235}}\mathit{U}$and${}^{\mathbf{238}}\mathit{U}$have the formula$\mathit{U}{\mathit{F}}_{\mathbf{6}}$. If you added heat at equal rates to a mole of$\mathit{U}{\mathit{F}}_{\mathbf{6}}$gas and a mole of${\mathit{H}}_{\mathbf{2}}$gas, which one’s temperature would you expect to rise faster? Explain.

It measures a specific number of ways the particular molecule moves, like rotation, molecules’s vibration, and translation. This quantity describes the state of any system.

The$U{F}_6$molecule has many more internal degrees of freedom (rotation, vibration) than$H_2$does.

Therefore, more heat is required for a given temperature change in$U{F}_6$ than$H_2$ , because for$U{F}_6$a larger fraction heat added goes into the internal motions of the molecule and less into the translation motion that determines the temperature.

Said another way,$C_v$ the polyatomic molecule$U{F}_6$ is larger than$C_v$ (diatomic molecule), so a given amount of heat flowing into the gas gives a smaller temperature rise in$U{F}_6$ .

Hence, the temperature of $H_2$rises faster thandata-custom-editor="chemistry" $U{F}_6$ because it has less degree of freedom.