3.00 mol
Explanation:
Given data:
Mass of Pâ‚„ = 211 g
Mass of oxygen = 240 g
Moles of Pâ‚‚Oâ‚… = ?
Solution:
Chemical equation:
P₄ + 5O₂    →   2P₂O₅
Number of moles of Pâ‚„:
Number of moles = mass/ molar mass
Number of moles = 211 g / 123.88 g/mol
Number of moles = 1.7 mol
Number of moles of Oâ‚‚ :
Number of moles = mass/ molar mass
Number of moles = 240 g / 32g/mol
Number of moles = 7.5 mol
Now we will compare the moles of product with reactant.
            O₂     :     P₂O₅
            5      :      2
            7.5    :     2/5×7.5 = 3.00
            P₄      :     P₂O₅
            1      :      2
            1.7     :    2×1.7 = 3.4 mol
Oxygen is limiting reactant so the number of moles of Pâ‚‚Oâ‚… are 3.00 mol.
Mass of Pâ‚‚Oâ‚…:
Mass = number of moles × molar mass
Mass = 3 mol ×283.9 g/mol
Mass = 852 g