First let us identify the molar masses:
NaF = 42 g/mol = 42 lb/lbmol
Na2SiF6 = 188 g/mol = 188 lb/lbmol
H2SiF6 = 144 g/mol = 144 lb/lbmol
F = 19 g/mol
Â
There is 1 F in every NaF, 6 F in every Na2SiF, and also 6 F in every H2SiF6. Therefore:
F in NaF = (100 / 42) * 1 * 19 = 45.23 lb = 21 kg
F in Na2SiF6 = (100 / 188) * 6 * 19 = 60.64 lb = 28 kg
F in H2SiF6 = (100 / 144) * 6 * 19 = 79.17 lb = 36 kg