Indium has two naturally occurring isotopes113In with an ato

Indium has two naturally occurring isotopes:^113In, with an atomic weight of 112.904 amu; and^115In, with an atomic weight of 114.904 amu. If the average atomic weight for In is 114.818 amu, calculate the fraction-of-occurrences of these two isotopes.

Solution

sol:

Given atomic weight of In 113 = 112.904 amu

atomic weight of In 115 = 114.904 amu

(112.9041) (x) + (114.9039) (1 - x) = 114.818

x = 0.0429