Answer to Question #54614 in Inorganic Chemistry for alex

Question

In nature, the element X consists of two naturally occurring isotopes. 107X with abundance 55.84% and isotopic mass 106.9051 amu and 109X with isotopic mass 108.9048 amu. Use the given information to calculate the atomic mass of the element X to an accuracy of .001% (Report your answer like this yyy.yyyy)

Answer 1

«W» is the mass fraction (abundance) of the isotope (%);
W(107X) = 55.84%;
W(109X) = 100 – 55.84 = 44.16%;
Ar – the relative atomic mass (a.m.u.) of the element. Symbol: u;
Ar107X = 106.9051 amu (u);
Ar109X = 108.9048 amu (u);
ArX=W(107X)*Ar107X+W(109X)*Ar109X
ArX = 106.9051*0.5584 + 108.9048*0.4416 = 59.6958 + 48.0924 = 107.7882 amu (u);
Answer: 107.7882