# Elemental chlorine consists mainly of two isotopes: ""^35Cl of 75% abundance; and ""^37Cl... What is the average atomic mass of chlorine?

May 11, 2017

About $35.5 \cdot \text{amu}$

#### Explanation:

Atomic mass is the weighted average of the individual isotopes.

And thus average atomic mass is given by the expression:

(0.75xx35(""^35Cl) +0.25xx37(""^37Cl))*"amu"=

$35.5 \cdot \text{amu}$