Question

Phosphoric acid, a mild acid used among other things as a rust inhibitor, food additive, and etching agent for cavity repair by dentists, can be made from elemental phosphorus in a two step process. In the first step, phosphorus and oxygen react to form diphosphorus pentoxide: P4(s) + 502(g) → 2P205(8) In the second step, diphosphorus pentoxide and water react to form phosphoric acid (H2PO4): P2O3(g) + 3 H20(1) ► 2H3PO4(1) Suppose the yield of the first step is 75.% and the yield of the second step is 77.%. Calculate the mass of phosphorus required to make 3.0 kg of phosphoric acid. Be sure your answer has a unit symbol, if needed, and is rounded to 2 significant digits.

Answer 1

P4 (5) +50₂8 2 P20519) P Orlg) + 3H20 (1) - 2H3PO412) yield actual x 1000 theoretical 0.77 = 3000g i theretical = 38969 theoretical moles of Blz P04 - 389 bg amo! " a 39.75 mol 2 moles of P2O5 = 39.75 - 19.81 mol actual moles of hos = 0.75x19.87 = 14,9 mol moles of P4 = 4.80 = 9.845 mol : 7.45 mol mass = 7.45x123.88= 9.2010 g 2