Question

Find the average atomic mass for li if 7.5% of li atoms are 6li with a mass of 6.0151223 amu and 92.5% are 7li with a mass of 7.0160041 amu.

Answer 1

We solve this problem by taking the average atomic mass which is solved by the sum of the product of individual atomic mass and mass fraction, that is:

atomic mass = 6.0151223 amu * 0.075 + 7.0160041 amu * 0.925

atomic mass = 6.4898 amu