Calculate the mass of phosphorus needed to react with oxygen to produce P₄O₁₀ such that when it dissolves in water, it creates 250 ml of a 2 M phosphoric acid solution.
- 15.5 g
- 31 g
- 62 g
- 7.75 g
📝 Detailed explanation
Moles of H₃PO₄ = 0.25 × 2 = 0.5 mol.P₄ + 5O₂ → P₄O₁₀.
P₄O₁₀ + 6H₂O → 4H₃PO₄.
Moles of P atoms required = 0.5 mol.
Mass of P = 0.5 × 31 = 15.5 g.