Chapter 11, Problem 11.12QP

The ²³⁵U isotope undergoes fission when bombarded with neutrons. However, its natural abundance is only 0.72 percent. To separate it from the more abundant ²³⁸U isotope, uranium is first converted to UF₆, which is easily vaporized above room temperature. The mixture of the ²³⁵UF₆ and ²³⁸UF₆ gases is then subjected to many stages of effusion. Calculate how much faster ²³⁵UF₆ effuses than ²³⁸UF₆.