Question

How many grams of oxygen will be absorbed from the atmosphere during the formation of iron (III) oxide from the oxidation of 78.2 g of iron in the presence of excess oxygen?

Answer 1

The reaction is 4FE + 3O_2 rightarrow 2Fe_2O_3 Molar mass of iron = 55.85 g Mass of iron reacting = 78.2 g(given) As per the balanced chemical equation, 4 moles of iron will react with 3 moles of oxygen (i.e 1 mole of iron will react with 3/4 mol of oxygen) Hence, for the given mass of iron, we have moles of iron no. of moles of iron = Weight of iron/Molar mass = 78.2 g/55.85 Rightarrow 1.4 moles of iron so, 1.4 mole of iron will react with 1.4 times 3/4 molo of oxygen i.e 1.05 mol of oxygen Rightarrow Weight of oxygen = Molar mass of oxygen times No. of moles = 16 times 1.05 = 16.8 g of oxygen