Mass of Fe₂O₃ : 74.26 g
Volume of O₂ at STP = 15.624 L
<h3>Further explanation</h3>
Reaction
4Fe (s) + 3O₂ (g) ==> 2Fe₂O₃ (s)
mol Fe :
Ar Fe = 56 g/mol

mol Fe₂O₃ :

mass Fe₂O₃ :
MW Fe₂O₃ : 159,69 g/mol

mol O₂ :

volume O₂ at STP(1 mol=22.4 L)

The density of a glass helps determine the weight of the optical assembly and, along with lens diameter, becomes critical for weight sensitive applications.
Answer:
Molecular formula: C₂H₄O₂
Empirical formula: CH₂O
Explanation:
40 % C, 6.72 % H and 53.29 % O states the centesimal composition of the compound. These data means that in 100 g of compound we have x grams of a determined element.
We divide the mass by the molar mass of each:
40 g / 12 g/mol = 3.33 moles of C
6.72 g / 1 g/mol = 6.72 moles of H
53.29 g / 16 g/mol = 3.33 moles of O
We can determine rules of three to get, the molecular formula.
In 100 g of compound we have 3.33 moles of C, 6.72 moles of H and 3.33 moles of O; therefore in 60 g (1 mol) we must have
- (60 . 3.33) / 100 = 2 moles of C
- (60 . 6.72) / 100 = 4 moles of H
- (60 . 3.33) / 100 = 2 moles of O
Molecular formula is C₂H₄O₂
Empirical formula has the lowest suscripts; we divide by two, so the empirical formula is CH₂O