Question

Question #390a5

Answer 1

`color(red)(z` = 36.938 u

Explanation:

The average atomic mass of an element is the sum of each of its isotopes multiplied by its abundance percentage:

#color(green )("avg. atomic mass" = sum_i ("isotope"_i xx "abundance"_i))#

Make
#color(red )(z#: the atomic mass of chlorine-37

Substituting values in equation above

35.446 u = (34.969 u × 0.7577) + (#color(red )(z# × 0.2423)

Solving for z:

`color(red)(z` = 36.938 u