The molar mass of (NH4)3PO4 is 149.087 grams per mole. Finding this answer involves using the number of atoms of each element in the molecular formula for this compound and their atomic masses.
From the molecular formula (NH4)3PO4, the number of atoms for each element is three atoms of nitrogen, twelve atoms of hydrogen, one atom of phosphorus and four atoms of oxygen. From the periodic table, the atomic masses for each element are nitrogen equals 14.0067 grams per mole, hydrogen is 1.00794, 30.973761 for phosphorus and oxygen is 15.9994.
To find the mass of the compound, which is ammonium phosphate, it is necessary to multiply the number of atoms of each element by their respective atomic mass and then add these quantities together: [(14.0067 grams/mol x 3) + (1.00794 grams/mol x 12 ) + (30.973761 grams/mol x 1) + (15.9994 grams/mol x 4)], which is equal to 149.087 grams per mole when rounded to the nearest thousandth.