Answer:
53.2
Explanation:
The balanced reaction is:
2Fe(s) + 3O₂(g) → Fe₂O₃
It means that 3 moles of oxygen form 1 mol of iron(III) oxide. The molar masses are: Fe = 55.8 g/mol and O = 16 g/mol. So
O₂ = 2x 16 = 32 g/mol
Fe₂O₃ = 2x55.8 + 3x16 = 159.6 g/mol
So, 32 g of O₂ corresponds to 1 mol of O₂. The stoichiometry calculus must be (always in moles):
3 mol of O₂ ------------------------ 1 mol of Fe₂O₃
1 mol of O₂ ------------------------ x
By a direct simple three rule:
3x = 1
x = 1/3 mol of Fe₂O₃
The mass is the molar mass multiplied by the number of moles, so:
m = 159.6x (1/3)
m = 53.2 g iron (III) oxide.
The moles of oxygen required to completely react with 1-mole acetylene is 2.5 mol.
The moles of reactant and product in a chemical reaction to the whole number ratio is given by the stoichiometric coefficient of the balanced chemical equation.
The vapor pressure of water at 50ºC will be greater than that at 10ºC because of the added energy and thus greater movement of the water molecules. If one knows the ∆Hvap at a given temperature, one can calculate the vapor pressure at another temperature. This uses the Clausius-Clapeyron (sp?) equation. It turns out the vapor pressure of water at 10º is 9.2 mm Hg, and that at 50º is 92.5 mm Hg.
