Hey there!
I think you meant to put iron (II) phosphate, because iron (I) phosphate isn't a thing.
So the formula for iron (II) phosphate is Fe₃(PO₄)₂.
Molar mass:
Fe: 3 x 55.845 = 167.535
P: 2 x 30.97 = 61.94
O: 8 x 16 = 128
-------------------------------------
357.475 grams/mole
The molar mass of iron(II) phosphate is 357.475 g/mol.
Hope this helps!
