Question

A soft silvery metal has two naturally occurring isotopes: mass 84.9118, accounting for 72.15% and mass 86.9092, accounting for 27.85%. The atomic weight of this metal would be:

Answer 1

Answer: The atomic weight of the metal would be 85.47.

Explanation:

Mass of isotope 1 of metal = 84.9118

% abundance of isotope 1 of metal = 72.15% = $\frac{72.15}{100}$

Mass of isotope 2 of metal= 86.9092

% abundance of isotope 2 of metal = 27.85% = $\frac{27.85}{100}$

Formula used for average atomic mass of an element :

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

$A=\sum[(84.9118)\times \frac{72.15}{100})+(86.9092)\times \frac{27.85}{100}]]$

$A=85.47$

Therefore, the atomic weight of the metal would be 85.47.