Question

Calculate the atomic mass of Carbon if the two common isotopes of carbon have masses of 12.000 amu (98.89 % abundance) and 13.003 amu (1.11 % abundance).

Answer 1

Average atomic mass =

(mass of isotope)(%abundance)+(mass of isotope) ( abundance ) / 100

avg. atomic mass =(12)(98.89) + (13)(1.11) /100

=1186.68 + 14.43 / 100

=1201.11 / 100

=12.0111