USA: +1 (725) 712-1730 
Sign in
Gallium is a metal which forms compounds with a wide variety of uses. Some of the applications of gallium compounds include computer memory chips, light emitting diodes and lasers. Radioactive isotopes of gallium are used to image the human body and locate tumors. Naturally occurring gallium consists of two isotopes. One of those isotopes is ^71Ga with an isotope mass of 70 9247050 amu and an abundance of 39.892%. What is the mass number of the other isotope?
Expert Answer
Answer
We will need the atomic mass of Ga, which is 69.723 amu; the atomic mass of Ga-71 is 70.9247050 amu and the natural abundance is 39.982%.
Convert the natural abundance to a decimal by dividing by 100; the value is 39.982/100 = 0.39982.
The natural abundance of the second isotope of Ga is (1 – 0.39982) = 0.60018.
Let the atomic mass of the second isotope be x amu.
Therefore,
70.9247050*0.39982 + x*0.60018 = 67.723
===> 28.35711555 + 0.60018x = 67.723
===> 0.60018x = 39.36588445
===> x = 39.36588445/0.60018 = 65.590130
The isotopic mass of the second isotope of Ga is 65.590130 amu (ans).
