Consider the reaction between H3PO4 and NH3 to produce (NH4)2HPO4. The molar mass of H3PO4 is 97.9937 g, (NH4)2HPO4 is 132.06 g, and NH3 is 17.0307 g. (a) What mass of ammonia would have to be added to 44.9 g of phosphoric acid if ammonia is required in 15% excess?