How to find the percentage abundance of isotope

Answer below (in explanation)

Explanation:

First find the average atomic mass of the element in question (on the periodic table)

Set up the relative abundance formula: (M1)(x) + (M2)(1-x) = M(E)

Where M1 = Mass of the first isotope, X = Relative abundance, M2 = mass of the second isotope, M(E) = Atomic mass of the element

Plug in your values (i'll use nitrogen as an example) :

(background info: The mass of one isotope, nitrogen-14, is 14.003 amu and another isotope, nitrogen-15, is 15.000 amu, find the relative abundance of the isotopes.

14.003x + 15.000(1-x) =14.007

Use algebra and solve for X. First use distributive property, combine like terms, and solve for X.

It would equal X = 0.996. Multiply by 100 to get a proper percentage and the percentage abundance of Nitrogen-14 is 99.6%

This way of solving is limited to 2 isotopes only.

Done