In order to answer this question we will use again the Avogadro's number, but now we are going to find out how many moles we have in 2.19*10^22 molecules of NaF
1 mol = 6.02*10^23 molecules
x moles = 2.19*10^22 molecules
x = 0.04 moles of NaF
Now that we have the number of moles, to find the mass we will need the molar mass of NaF, which is 42 g/mol, this means that for every mol of NaF, we will have 42 grams of it
42 g = 1 mol
x grams = 0.04 moles
x = 1.68 grams of Sodium fluoride, NaF
