Question

The element Eu occurs naturally as a mixture of 47.82% 151 63Eu and whose mass is 150.9 amu, and 52.18% 151 63Eu whose mass is 152.9 amu. What is the average atomic mass of Eu?

Answer 1

To calculate the average atomic mass of Eu, we need to consider the relative abundance and mass of its isotopes.

Given:

• Isotope 63Eu has a relative abundance of 47.82% and a mass of 150.9 amu.
• Isotope 65Eu has a relative abundance of 52.18% and a mass of 152.9 amu.

To find the average atomic mass, we can use the weighted average formula:

Average Atomic Mass = (Abundance₁ * Mass₁) + (Abundance₂ * Mass₂) + ...

Let's plug in the values:

Average Atomic Mass = (0.4782 * 150.9 amu) + (0.5218 * 152.9 amu)

Calculating the expression:

Average Atomic Mass = (72.17338 amu) + (79.84222 amu) Average Atomic Mass ≈ 152.02 amu

Therefore, the average atomic mass of Eu is approximately 152.02 amu.