Question

An unknown element X has the following isotopes: ²⁵X (80.5% abundant) and ²⁷X (19.5% abundant). What is the average atomic mass in amu of X?

Answer 1

25.39

Step-by-step explanation:

Given parameters:

Abundance of X-25 = 80.5%

Abundance of X - 27 = 19.5%

Unknown:

Average atomic mass of X = ?

Solution:

The average atomic mass of X can be derived using the expression below:

Average atomic mass = (abundance x mass of X - 25) + (abundance x mass of X - 27)

Average atomic mass = (80.5% x 25) + (19.5% x 27) = 25.39