Chapter 16, Problem 11STP

To determine

To Find: The average atomic mass of chlorine.

Answer to Problem 11STP

35.5 amu.

Explanation of Solution

Introduction:

The chlorine has two isotopes, and they are chlorine-35 and chlorine-37. The average mass of chlorine depends on the abundance of its isotopes.Three chlorine atoms are chlorine-35 and one is chlorine-37.

The chlorine consists of two major isotopes one is with 18 neutrons and it is 75.77% and another with 20 neutrons that is 24.23% of natural chlorine atoms.

By conversing the percentage to the decimal form

  $\text{24}\text{.47\%}\text{= }\frac{24.47}{100}=0.2447$

  $75.53\%=\frac{75.53}{100}=0.7553$

By multiplying and adding mass abundance by its percentage.

The average atomic mass of isotopes of chlorine is

  $\left\{\left(35\times 0.7577\right)+\left(37\times 0.2423\right)\right\}=35.5\text{ amu}$

Hence, the average atomic mass is 35.5 amu.

Conclusion:

The average atomic mass of the chlorine is 35.5 amu.