Question

A fictitious element X is composed of 10.0 percent at 24.3 amu, 20.0 percent at 25 amu, and 70.0 percent at 25.5 amu. Calculate the average atomic mass of element X.

Answer 1

To find the average atomic mass of element X, multiply each isotope's mass by its relative percentage (as a decimal) and add the values together, giving an average atomic mass of 25.28 amu.

Step-by-step explanation:

To calculate the average atomic mass of the fictitious element X, you must consider each isotope's mass and its relative abundance. The average atomic mass is a weighted average, which means that we multiply the mass of each isotope by its percentage abundance (expressed as a decimal) and then sum these products together.

The calculation would look like this:

• (0.100 × 24.3 amu) + (0.200 × 25 amu) + (0.700 × 25.5 amu)
• (2.43 amu) + (5.00 amu) + (17.85 amu)
• 25.28 amu

Therefore, the average atomic mass of element X is 25.28 amu.