MolMass is a java applet which calculates all possible molecule
masses on the basis the isotopes of the constituent atoms. The
program lets you enter the molecule you want to investigate (e.g.
CH4). When hitting the calculate button it will calculate the
different molecule masses and their abundancy.
Consider CH4 as an example. Since there are the isotopes
12C and 13C, and 1H and
2H involved, there are a number of possible masses that
can be produced. When you would run this example in the program the
results are as follows: There will be a chance of 98.83% of
producing CH4 with a mass of 16. In addition there will be a chance
of 1.17% of producing CH4 with a mass of 17. The reason why masses
of 18-20 don't appear is that their abundancy is very very
To run MolMass you need to run a java enabled
|Relative abundancies of CH4 masses||Abundancies scaled to the highest|
Please find more screen shots here.