In the gravimetric determination of phos- phorus, an aqueous solution of the dihydrogenphosphate ion (HPO4) was treated with a mixture of ammonium (NH4+) and magnesium (Mg2+) ions to precipitate magnesium ammonium phosphate (MgNHPO4 6HO). This was heated and decomposed into magnesium pyrophosphate (MgPO7), which was weighed. The net reactions are HPO4 + Mg2+ + NH4+ + 6HO MgNHPO4 6HO(s) + 2H+, 6HO(s) MgPO7(s) + 2NH3(g) + 13HO(g). 2MgNH4PO4 A solution of HPO4 yields 1.054 g of MgPO. What weight of NaHPO4 would be required to give the original amount of HPO4?