Use the Chem Periodic table to find the molar mass.
moles = mass / molar mass
H2O = 18.....................................4.50/18 = 0.25 mol
Ba(OH)2 = 171.327.....................471.6/171.327 = 2.75 mol
Fe3(PO4)2 = 357.482524.......129.68/357.482524 = 0.36 mol
