Question

Bromine has two naturally occurring isotopes. One of them, bromine -79 has a mass of 78.9183 u and an abundance of 50.69%. What must be the mass and percent natural abundance of the other, bromine-81?

Answer 1

Question #45233, Chemistry, Inorganic Chemistry

Molar mass of mixture of isotopes is equal to follow expression:

$$M = M _ {1} \omega_ {1} + M _ {2} \omega_ {2}$$

Where $M_1$ and $M_2$ are molar mass of isotopes, $\omega_1$ and $\omega_2$ are mass ratio of isotopes in the mixture.

$$M _ {2} = \frac {M - M _ {1} \omega_ {1}}{\omega_ {2}} = \frac {79.904 - 78.973 \times 50.69}{49.31} = 81.1832 \text{ - is molar mass of Bromie-81}$$

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