Oxygen is composed of three isotopes 16/8 O (15.995 u), 17/8 O (16.999 u) and 18/8 O (17.999 u). One of these isotopes, 17/8 O, comprises of 0.037% of oxygen. What is the percentage abundance of the other two isotopes, using the average atomic mass of 15.9994 u.
1 Answer
Jun 23, 2014
The abundance of
Assume you have 100 000 atoms of O. Then you have 37 atoms of
Let x = the number of atoms of
The total mass of 100 000 atoms is
x × 15.995 u + (99 963 – x) × 17.999 u + 37 × 16.999 u = 100 000 × 15.9994 u
15.995 x + 1 799 234.037 – 17.999 x + 628.963 = 1 599 940
2.004 x = 199 123
x = 199 123/2.004 = 99 762
So there are 99 762 atoms of
The number of
Hope this helps.
