Question

Challenge

Chlorine has two possible isotopes. You must use at least one atom of each isotope. What
combination of the number of atoms and isotopes will come closest to the actual average atomic mass
of 35.45? Show your combination below. What does this mean about the percent abundance of these
isotopes? (Remember, the 2 percent values must add up to 100%)

Answer 1

The average atomic mass of chlorine can be calculated using the percentage abundances and atomic masses of each isotope. A combination of 75.77% chlorine-35 and 24.23% chlorine-37 will come closest to the actual average atomic mass of 35.45 amu for chlorine. The percent abundances reflect the proportion of each isotope in a natural sample of chlorine.

Step-by-step explanation:

The element chlorine has two naturally occurring isotopes: chlorine-35 and chlorine-37. The abundance of these isotopes in a natural sample is 75.77% chlorine-35 and 24.23% chlorine-37.

To calculate the average atomic mass of chlorine, we need to use the percentage abundance and atomic masses of each isotope. Chlorine-35 has an atomic mass of 34.969 amu and a percentage abundance of 75.77%. Chlorine-37 has an atomic mass of 36.966 amu and a percentage abundance of 24.23%.

We can now calculate the weighted average atomic mass by multiplying the atomic mass of each isotope by its respective percentage abundance and summing the results: (34.969 amu * 0.7577) + (36.966 amu * 0.2423) = 35.45 amu.

This means that a combination of 75.77% chlorine-35 and 24.23% chlorine-37 will come closest to the actual average atomic mass of 35.45 amu for chlorine.

The percent abundance of these isotopes reflects the proportion of each isotope in a natural sample of chlorine. In this case, chlorine-35 is more abundant at 75.77%, while chlorine-37 is less abundant at 24.23%.