Explanation:
A mixture of differet iron oxides is heated and they it absorbs oxygen from the air to form iron (II) oxide. The reaction can be represented like this:
2 Fe₃O₄ + 2 FeO + O₂ ----> 4 Fe₂O₃
The mass of the mixture of Iron oxides is 3.939 g. The mass of Fe₂O₃ formed is greater than the original mass, it is 4.197 g. That means that the sample absorbed oxygen.
mass of Fe₃O₄ + mass of FeO = 3.939 g
mass of Fe₂O₃ = 4.197 g
The law of conservation of mass states that no mass is loss or created in a chemical reaction. A mass balance can be written:
mass of Fe₃O₄ + mass of FeO + mass of O₂ = mass of Fe₂O₃
The known values can be replaced in the equation, and it can be solved for mass of O₂ to obtain the answer to the problem.
mass of Fe₃O₄ + mass of FeO + mass of O₂ = mass of Fe₂O₃
mass of O₂ = mass of Fe₂O₃ - (mass of Fe₃O₄ + mass of FeO)
mass of O₂ = 4.197 g - 3.939 g
mass of O₂ = 0.258 g
Answer: the mass of oxygen reacted is 0.258 g
