Chapter U1.13, Problem 7E

Interpretation Introduction

Interpretation:

Average atomic weight of two given isotopes of chlorine must be calculated.

Concept introduction:

Isotope is defined as the atom having same atomic number but different mass number. Basically, two isotopes have different number of neutrons present in them.

Answer to Problem 7E

Average atomic weight of chlorine is 35.48 amu.

Explanation of Solution

The atomic weight of chlorine can be calculated using the atomic mass of two isotopes and their respective percent abundance.

The formula used is as follows:

$M_{\text{average}}={\displaystyle \sum \%\text{abundance}\times \text{atomic mass}}$

Putting the values,

$\begin{array}{l}{M}_{\text{average}}=\frac{76\%\times 35\text{ amu}+24\%\times 37\text{ amu}}{100}\\ =35.48\text{ amu}\end{array}$

Conclusion

Thus, the average atomic weight of Cl is 35.48 amu.