Burned 6.2 grams of phosphorus. Find the mass of the resulting oxide, if its yield is 98%?

The reaction equation for the combustion of phosphorus:

4P + 5O2 = 2P2O5

Let’s find the amount of substance P:

v (P) = m (P) / M (P) = 6.2 / 31 = 0.2 (mol).

According to the reaction equation, from 4 mol of P, 2 mol of P2O5 is formed. In addition, the P2O5 yield (98%) must be considered. Therefore, the amount of substance P2O5:

v (P2O5) = (v (P) / 2) * 0.98 = (0.2 / 2) * 0.98 = 0.098 (mol).

Thus, the mass of the formed phosphorus oxide (V):

m (P2O5) = v (P2O5) * M (P2O5) = 0.098 * 142 = 13.916 = 13.9 (g).