The number of moles of anything is calculated from the mass
of sample and the molar mass. The molar mass of Fe(NH4)2(SO4)2.6H2O
is 392.2 g. For sample 1, in which the mas of FAS taken was 1.0092 g,
the number of moles of FAS present is given by the following:
moles FAS = (1.0092 g FAS)[1 mole FAS/392.2 g FAS] = 0.002573 moles
FAS