Answer:
Molecular formula = P₄O₆
Explanation:
P(s) + O₂(g)------------------------------------⇒ PₓOₙ (g)
10g (17.77-10)g 17.77g
10g 7.77g 17.77g (gramme ratio)
The molecular mass of Phosphorus (P) = 31g/mole
The molecular mass of Oxygen atom (O) = 16g/mole
Mole ratio is given by:
P : O
10/31 7.77/16
0.3226 : 0.4856 Mole ratio---------------------------- (1)
Divide (1) through by 0.3226
1 : 1.5-------------------------------------------- (2)
From (2), the empirical formula for Phosphorus oxide :
Empirical formula = P₁O₁.₅
= PO₁.₅
The molecular formula can be calculated from below:
Since the molecular formula is a multiple of the empirical formula we have
Molecular formula = (PO₁.₅)ₙ----------------------------------- (3)
Since we are given the molecular mass of the oxide formed, we have:
(PO₁.₅)ₙ = 220-----------------------------(4)
[31 + (16 x 1.5)] x n = 220
[31 + 24]n = 220
55n =220
n = 4
Substituting into (3), we have :
Molecular formula = (PO₁.₅)₄
= P₄O₆
