Question: what is the gram-formula mass of (nh4)3po4?
Answer: Molar Mass = 3(14.0) + 12(1.0) + 31.0 + 4(16.0) = 149 g/mol . Step 3: Divide the mass of nitrogen by the molar mass of (NH4)3PO4 and multiply by 100% to get percent mass. Step 4: Find the total mass of all the hydrogen atoms in one mole of the compound.