Question

An element has the following natural abundances and isotopic masses: 90.92% abundance with 19.99 amu, 0.26% abundance with 20.99 amu, and 8.82% abundance with 21.99 amu. Calculate the average atomic mass of this element.​

Answer 1

20.16 amu

Explanation:

An element has the following natural abundances and isotopic masses: 90.92% abundance with 19.99 amu, 0.26% abundance with 20.99 amu, and 8.82% abundance with 21.99 amu. Calculate the average atomic mass of this element.

Answer 2

Answer:

Explanation:

Concept:

The weighted average mass of the atoms in a naturally occurring sample of an element is the average atomic mass, also known as atomic weight. Unified atomic mass units (u), where 1 u is equal to precisely one-twelfth the mass of a neutral atom of carbon-12, are the standard units used to express average masses.
Solution:

Average atomic mass is given by

$\begin{aligned}&=\frac{\text { (atomic mass } \left.\times \% \text { abundance })_{1}+\text { (atomic mass } \times \% \text { abundance) }\right)_{2}+(\text { atomic mass } \times \%)}{100}\\\\&=\frac{((19.99 \times 90.92)+(20.99 \times 0.26)+(21.99 \times 8.82))}{100}=20.16 \mathrm{amu}\end{aligned}$

The average atomic mass of this element is 20.16 amu

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