Element Fictionium (Fc) has three isotopes. The first, Fc-112 has a mass of 112.4469 amu and makes up 20.62% of a standard sample. The second isotope, Fc-114 has a mass of 113.5518 amu and makes up 57.00% of a standard sample. The third isotope, Fc-115 has a mass of 115.3332 amu and makes up the remainder of a standard sample. What is the average atomic mass of this element?

Question

abmon98 · Answer

Isotope     Mass        % Abundance   Portion of Average
FC-112: 112.4469     20.62           112.4469*20.62/100
FC-114  113.5518     57.00           113.5518*57.00/100
FC-115  115.3332     22.38           115.3332 *22.38/100
Sum Portion of Average
Note that % Abundance should Add up to 100 that's why i added 20.62 to 57.00 and subtracted it from 100 to obtain the % abundance of Isotope of FC-115