Question

Question 7:

a) Iron is the main ingredient of steel, an alloy used in many building structures. As oxygen reacts with it, it turns into iron (III) oxide. It’s a yellow/red colour that flakes off from the metal to expose more pure iron to oxygen. Write a balanced reaction. 3 marks

b) If 0.76 mol Iron reacts with 0.99 mol oxygen, using limiting reagents, how much iron (III) oxide, in grams, will form? 5 marks

c) You are investigating this reaction in the lab, you weigh out 20.01g iron into a sealed chamber. You extract all gasses from the chamber and then fill it with 17.23g oxygen. Firstly, how much iron (III) oxide will be formed in grams? Secondly, how much of the excess reactants will remain? 9 mark

Answer 1

(s) a. 4fe (s) + 3 O₂ (g) > 2 Fe₂O3 b. 4 Fe it 302 2 Fez Og 0.76 mol 0.99 mol Limiting reagent Mole of Fe2O3 = 2 x mole of Fe 4 1 / 2 x 0.76 = 0.38mol Mass of Fe2O3 0.38mol x 159.69 g/mol 160.68 C. 4 Fe + 302 > 2Fe₂O3 20:013 17.233 17 23 mol 32 55.8 20.01 mol 0.5384 mol 0.3586 mol Limiting reagent Mole of Fe 2 Og = 0.3 586 mol Mass of Fe2O3 = 1.59-69 X0:3586 g 2 2 57.32 هه to remain = role of Or 0.5384-0.3586 2 = 0.359 mol Mass of O2 remain = 0.359 x 32 g 11.99 مح