更新1:
One way to analyze for the amount of phosphorus in a rock is to precipitate the phosphorus as MgNH4PO4 which is then heated to turn it into Mg2P2O7. What weight of Mg2P2O7 will be obtained from a 2.558 g sample of a rock that contains 86.52% Ca3(PO4)2 (and no other source of phosphorus) if this analysis is done?
