Naturally occurring cobalt consists of only one isotope, 59Co, whose relative atomic mass is 58.9332. A synthetic radioactive isotope of cobalt, 60Co, relative atomic mass 59.9338, is used in radiation therapy for cancer. A 1.3938-g sample of cobalt has an apparent "atomic mass" of 58.9947. Find the mass of 60Co in this sample.

Any and all help is very much appreciated! :)

## Have a look at http:/

Have a look at http://yeahchemistry.com/tutorials/atomic-masses-and-isotopic-abundances

for the basic method. Let the % of Co59 be w, so % of Co60 = (100-w). Then

(w/100) x 58.9332 + ((100-w)/100) x 59.9338 = 58.9947

w x 58.9332 + (100-w)/x 59.9338 = 5899.47

Solve for w. You then find 100-w as the percentage of Co60, and find this fraction of 58.9947

'Chemistry is not just the study of matter; Chemistry is the study which matters!' - Kingchemist