Using a chemical equation to find moles

Question

Ammonium phosphate NH43PO4 is an important ingredient in many solid fertilizers. It can be made by reacting aqueous phosphoric acid H3PO4 with liquid ammonia. Calculate the moles of ammonium phosphate produced by the reaction of 1.7mol of ammonia. Be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits. 

Answer 1

Note: liquid ammonia (NH₃₎ is actually aqueous ammonium hydroxide (NH₄OH) because NH₃ + H₂O -> NH₄OH.

H₃PO₄(aq) + 3NH₄OH(aq) ==> (NH₄)₃PO₄ + 3H₂O ... balanced equation

Assuming that H₃PO₄ is not limiting, i.e. it is present in excess, then ...

1.7 mol NH₄OH x 1 mole (NH₄)₃PO₄/3 moles NH₄OH = 0.567 moles = 0.57 moles (NH₄)₃PO₄ (2 sig. figs.)