Copper is composed of two isotopes, one of mass 62.9298 amu and one of mass 64.9278amu. Calculate the percentage of each isotope. Please explain the solution in detail.
Example #2a: Copper is made up of two isotopes, Cu-63 (62.9296 amu) and Cu-65 (64.9278 amu). Given copper's atomic weight of 63.546, what is the percent abundance of each isotope? Solution: 1) Write the following equation: (62.9296) (x) + (64.9278) (1 - x) = 63.546 Once again, notice that 'x' and 'one minus x' add up to one. 2) Solve for x: x = 0.6915 (the decimal abundance for Cu-63) Note that this calculation technique works only with two isotopes. If you have three or more, there are too many variables and not enough equations. I hope it's obvious why you wouldn't do this with an element that has only one stable isotope! By the way, the 'trick' works because the other equation required is: x + y = 1 We simply went right to y = 1 - x and substitued it immediately without ever writing down the second equation required. Hope that helps:)
