The equation for the reaction of phosphorus with oxygen:
4P + 5O2 = 2P2O5
The amount of substance P2O5:
v (P2O5) = m (P2O5) / M (P2O5) = 71/142 = 0.5 (mol).
According to the reaction equation, 2 mol of P2O5 is formed from 4 mol of P, therefore:
v (P) = v (P2O5) * 4/2 = 0.5 * 4/2 = 1 (mol).
Thus, the required mass of phosphorus:
m (P) = v (P) * M (P) = 1 * 31 = 31 (g).
Answer: 31 g.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.