There are two important isotopes of uranium — 235U and 238U; these isotopes are
ID: 1444976 • Letter: T
Question
There are two important isotopes of uranium — 235U and 238U; these isotopes are nearly identical chemically but have different atomic masses. Only 235U is very useful in nuclear reactors. One of the techniques for separating them (gas diffusion) is based on the different average speeds vrms of uranium hexafluoride gas, UF6. (Use k = 1.38 10-23 J/K for this question.)
(a) The molecular masses for 235UF6 and 238UF6 are 349.0 g/mol and 352.0 g/mol, respectively. What is the ratio of their average speeds? (Enter your answer to at least 4 decimal places.) v235 v238 =
(b) At what temperature would their average speeds differ by 1.60 m/s? K
Explanation / Answer
vrms = sqrt(3kT/m)
v235/v238 = sqrt(352/349)
v235/v238 = 1.008595989