Phosphorus with a mass of 15.5 g was burned in an excess of oxygen. The resulting phosphorus oxide

Phosphorus with a mass of 15.5 g was burned in an excess of oxygen. The resulting phosphorus oxide was dissolved in excess water and heated to boiling. The mass of the acid contained in the solution was 46.55 g. What is the acid yield from the theoretically possible?

Given:
m (P) = 15.5 g
m pract. (acid) = 46.55 g

Find:
η (acid) -?

Solution:
1) 4P + 5O2 => 2P2O5;
P2O5 + 3H2O => 2H3PO4;
2) M (P) = Mr (P) = Ar (P) = 31 g / mol;
M (H3PO4) = Mr (H3PO4) = Ar (H) * N (H) + Ar (P) * N (P) + Ar (O) * N (O) = 1 * 3 + 31 * 1 + 16 * 4 = 98 g / mol;
3) n (P) = m (P) / M (P) = 15.5 / 31 = 0.5 mol;
4) n (P2O5) = n (P) * 2/4 = 0.5 * 2/4 = 0.25 mol;
5) n theory. (H3PO4) = n (P2O5) * 2 = 0.25 * 2 = 0.5 mol;
6) m theor. (H3PO4) = n theory. (H3PO4) * M (H3PO4) = 0.5 * 98 = 49 g;
7) η (H3PO4) = m practical. (H3PO4) * 100% / m theor. (H3PO4) = 46.55 * 100% / 49 = 95%.

Answer: The H3PO4 yield is 95%.