what is the average atomic mass of 125 atoms of uranium if there are 10 atomd of U-234, 75 atoms of U-235, and 40 atoms of U-238?

Question

Cedric Hayden

Chemistry

26 July, 08:32

what is the average atomic mass of 125 atoms of uranium if there are 10 atomd of U-234, 75 atoms of U-235, and 40 atoms of U-238?

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Answers (1)

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Natalya Leach · Answer 1

Answer is: the average atomic mass of 125 atoms of uranium is 235.88.

ω (U-234) = 10 : 125.

ω (U-234) = 0.080.

ω (U-235) = 75 : 125.

ω (U-235) = 0.60.

ω (U-238) = 40 : 125.

ω (U-238) = 0.320.

Average atomic mass of atoms of uranium =

Ar (U-234) · ω (U-234) + Ar (U-235) · ω (U-235) + Ar (U-238) · ω (U-238).

Average atomic mass of atoms of uranium =

234 · 0.08 + 235 · 0.6 + 238 · 0.32.

Average atomic mass of atoms of uranium = 18.72 + 141 + 76.16.

Average atomic mass of atoms of uranium = 235.88.