Question

Only two stable isotopes of chlorine exist. 35Cl has a mass of 34.96885 amu and 37Cl has a mass of 36.9659 amu. Given that the atomic mass of chlorine is 35.453, calculate the isotopic abundance of 37Cl. (Enter your answer as a decimal number between zero and one.)

Answer 1

Answer: The isotopic abundance of Cl- 37 is 0.2424.

Explanation:

Mass of isotope - 35 = 34.96885 amu

% abundance of isotope -35= x% = $\frac{x}{100}$

Mass of isotope - 37 = 36.9659 amu.

% abundance of isotope-37 = (100-x)% = $\frac{100-x}{100}$

Formula used for average atomic mass of an element :

$\text{ Average atomic mass of an element}=\sum(\text{atomic mass of an isotopes}\times {{\text { fractional abundance}})$

$35.453=\sum[(34.96885 \times \frac{x}{100})+(36.9659 \times \frac{100-x}{100}]]$

$x=75.76\%$

$(100-75.76)=24.24\%=0.2424$

Therefore,  the isotopic abundance of Cl- 37 is 0.2424.