Question

Calculate the atomic mass (average) of chlorine using the following data:
$\begin{array}{ccc}\text{Isotopes}& \text{\%Natural Abundance}& \text{Molar Mass}\\ {}^{35}Cl& 75.77& 34.9689\\ {}^{37}Cl& 24.23& 36.9659\end{array}$

Answer 1

The average atomic mass of Cl:
The average atomic weight is the total weight of the sample divided by the number of molecules in the sample.
$\therefore \text{Average atomicmassofchlorine}=\sum m_i\frac{A_i}{100}$
$m_i=\text{isotopicatomicmass}$
$A_i=\text{\% abundanceofisotope}$
$\text{Average atomicmass ofchlorine}=(34.9689\times \frac{75.77}{100})+(36.9659\times \frac{24.23}{100})$
$=[26.4959+8.9568]u$
$=35.4527u$
Final Answer: The average atomic mass of Cl is 35.4527 u.