How to calculate the percent composition of F in NaF?

Answer 1

To find percent composition, you must work with the atomic masses. Look on a periodic chart to find the atomic masses of F and Na. You will find that Na has an Atomic Mass of 22.990 grams per mole of Na and that F has an atomic mass of 18.998 grams per mole of F.

So, add these both together, and that will tell you how much mass NaF will be. NaF will have a mass of 41.988 grams per mole of NaF.

Now to take the percent composition of F in NaF, simply divide the mass of F by the mass of NaF. That will give you [18.998/41.988]=.452 which will be about 45%.

So your answer is that F has a 45% composition of NaF.

PS: Since Na and F only had a stoichiometry of 1 (meaning there is 1 Na and 1 F in the molecule), no multiplication of the atomic masses was necessary when calculating the total mass of the molecule.