Question

Ordinary chlorine has two isotopes${}_{17}^{35}Cl$ and${}_{17}^{37}Cl$ in the ration of 3:1 Calculate the relative atomic mass of chlorine.

Answer 1

1. Given that:

Isotope one = ${}_{17}^{35}Cl$

Isotope two = ${}_{17}^{37}Cl$

2. The percentage of the abundance of ${}_{17}^{37}Cl$ is 25%

3. The percentage of the abundance of ${}_{17}^{35}Cl$ is 75%

4. Now, the average atomic mass of chlorine can be calculated as:

Average atomic mass = relative abundance of ${}_{17}^{35}Cl$ isotope $\times$ atomic mass of ${}_{17}^{35}Cl$ $+$ relative abundance of ${}_{17}^{37}Cl$ $\times$ atomic mass of ${}_{17}^{37}Cl$ isotope

$=(37\times 0.25)+(35\times 0.75)$

$=9.25+25.25$

$=35.5u$

Hence, The relative atomic mass of chlorine is 35.5 u.