Question

How to find the average atomic mass of sulfur from the following data:

$\mathrm{S}-3295.002\%(31.972),\mathrm{S}-330.76\%(32.971),\mathrm{S}-344.22\%(33.967),\mathrm{and}\mathrm{S}-360.014\%(35.967)$?

Answer 1

Step 1: Given Data

• The atomic masses of four isotopes of sulfur are:
• ${}^{32}\mathrm{S}:31.972\mathrm{u}\to 95.002\%$
• ${}^{33}\mathrm{S}:32.971\mathrm{u}\to 0.76\%$
• ${}^{34}\mathrm{S}:33.967\mathrm{u}\to 4.22\%$
• ${}^{36}\mathrm{S}:35.967\mathrm{u}\to 0.014\%$

Step 2: Calculation of Average atomic mass

The average atomic mass of a chemical element is calculated by taking into account the atomic masses of its naturally occurring isotopes and their respective abundances.

The formula used for the calculation of average atomic mass is $\sum _{}^{}\mathrm{i}(\mathrm{isotope}\times \mathrm{abundance})$

By substituting the values in the above formula we get the average atomic mass:

$$\begin{gathered} (31.972\mathrm{u}\times 0.95002)+\left(32.971\mathrm{u}\times 0.0076\right)+\left(33.967\mathrm{u}\times 0.0422\right)+\left(35.967\mathrm{u}\times 0.00014\right) \\ =32.063\mathrm{u} \end{gathered}$$

Therefore, Average atomic mass of Sulfur= $32.063\mathrm{u}$.