The atomic mass of chlorine is listed as 35.454 amu on the periodic table. It has two naturally occurring isotopes, Cl-35 and Cl-37. What are the approximate percentages of each?

Question

I have no idea how to figure out the percentages for this. I know how to determine the atomic mass based on given isotopes, but I'm not sure how to figure out the percentages when given the mass. Would I somehow work backwards?

Answer 1

35.452*100=35*X+37(100-x)
solve for x,the percentage of isotope 35