Chemical reactions

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 ammonia needed to produce 0.055mol

 of ammonium phosphate. Be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits.

Answer 1

Write the correctly balanced equation for the reaction:

H₃PO₄(aq) + 3NH₃(l) ==> (NH₄)₃PO₄

Use the stoichiometry (mole ratio) of this equation and dimensional analysis to get the answer:

0.055 mol (NH₄)₃PO₄ x 3 mol NH₃ / 1 mol (NH₄)₃PO₄ = 0.165 mols NH₃ = 0.17 mols NH₃ (2 sig.figs.)

(note: units are mols and significant figures = 2 since 0.055 has only 2 sig.figs.)