169k views
3 votes
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.

User Dave Hein
by
7.8k points

1 Answer

5 votes

Final answer:

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.

User Keven
by
8.4k points