# Answer to Question #228292 in General Chemistry for nin

Question #228292

Li has two naturally occurring isotopes, 6

Li (isotopic mass 6.0151 amu) and 7

Li (isotopic mass 7.0160 amu).

Calculate the percentage abundance of each isotope if the atomic mass of lithium is 6.941 amu.

1
2021-08-22T07:30:04-0400

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows: Let the fractional abundance of Li isotope-1 be 'x' and the fractional abundance of Li isotope-2 will be '100-x'

For Li isotope-1 :

Mass of Li isotope-1 = 6.01512 amu

Fractional abundance of Li isotope-1 = x

For Li isotope-2 :

Mass of Li isotope-2 = 7.01600 amu

Fractional abundance of Li isotope-2 = 100-x

Average atomic mass of Li = 6.941 amu

Putting values in equation 1, we get: By solving the term 'x', we get: Percent abundance of Li isotope-2 = 100 - x = 100-6.94 = 93.1 %

Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!