Question

The atomic mass of lithium is 6.94. The naturally occurring isotopes are 6Li = 6.015121 amu and 7Li = 7.016003 amu. Determine the percent abundance of each isotope.

Answer 1

The percent abundance of 6Li is 7.60% and the percent abundance of 7Li is 92.40%.

Step-by-step explanation:

In order to determine the percent abundance of each isotope of lithium, we can use the given information about the atomic mass and the masses of the isotopes.

Let's assume that the percent abundance of 6Li is x and the percent abundance of 7Li is 100-x. Since the atomic mass of lithium is the weighted average of the masses of its isotopes, we can set up the following equation:

6.94 = (x/100)(6.015121) + (100-x)(7.016003)

Solving this equation yields x = 7.60%, which is the percent abundance of 6Li, and 100-x = 92.40%, which is the percent abundance of 7Li.