Chapter 10, Problem 27PE

Bromine has two isotopes with masses of 78.9 and 80.9 (to three significant figures), respectively. Bromine boils at $\text{59 °C}\text{. At 75 °C}$. what is the expected ratio of the rate of effusion of ${}^{\text{81}}{\text{Br—}}^{\text{81}}\text{Br}$ compared to ${}^{\text{81}}{\text{Br—}}^{\text{79}}{\text{Br and}}^{\text{79}}{\text{Br—}}^{\text{79}}\text{Br}$? (Hint: How do the rates of effusion relate to the molecular masses of gases?)