Final answer:
To find the mass of P2O5 in a fertilizer sample and its percentage, the molar mass conversion is first determined and then applied to the initial sample mass. The percentage is then calculated by mass comparison.
Step-by-step explanation:
To calculate the value for the mass of P2O5 in the initial mass of fertilizer analyzed from a 3.02g sample of MgNH4PO4x6H2O, we need to know the molar mass of MgNH4PO4x6H2O and the molar mass of P2O5. By using the molar mass of the compounds, including the phosphorus pentoxide molecule, we can create a conversion factor to find how much P2O5 comes from the given amount of MgNH4PO4x6H2O. After finding the mass of P2O5, the percent P2O5 in the fertilizer is calculated by (mass of P2O5/mass of sample) x 100%.