iGCSE Chemistry 0620 Extended - 9.6 Extraction of metals- Exam Style Questions Paper 2- New Syllabus
▶️ Answer/Explanation
In the extraction of aluminium by electrolysis:
At the anode (+), oxidation occurs. Reaction 3 (\(\mathrm{2O^{2-} \rightarrow O_2 + 4e^-}\)) is the oxidation of oxide ions at the anode. Reaction 2 (\(\mathrm{C + O_2 \rightarrow CO_2}\)) also occurs at the anode as the oxygen produced reacts with the carbon anodes, causing them to be regularly replaced.
Reaction 1 is reduction and occurs at the cathode (−).
✅ Answer: (C)
At the anode (+), oxidation occurs. Reaction 3 (\(\mathrm{2O^{2-} \rightarrow O_2 + 4e^-}\)) is the oxidation of oxide ions at the anode. Reaction 2 (\(\mathrm{C + O_2 \rightarrow CO_2}\)) also occurs at the anode as the oxygen produced reacts with the carbon anodes, causing them to be regularly replaced.
Reaction 1 is reduction and occurs at the cathode (−).
✅ Answer: (C)
▶️ Answer/Explanation
Step 1: Coke (carbon) is completely oxidised at the bottom of the furnace: \(\mathrm{C + O_2 \rightarrow CO_2}\) (provides heat).
Step 3: Carbon dioxide is reduced to carbon monoxide: \(\mathrm{CO_2 + C \rightarrow 2CO}\).
Step 2: Iron(III) oxide is reduced by carbon monoxide: \(\mathrm{Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2}\).
Correct order: 1 → 3 → 2.
✅ Answer: (B)
Step 3: Carbon dioxide is reduced to carbon monoxide: \(\mathrm{CO_2 + C \rightarrow 2CO}\).
Step 2: Iron(III) oxide is reduced by carbon monoxide: \(\mathrm{Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2}\).
Correct order: 1 → 3 → 2.
✅ Answer: (B)
▶️ Answer/Explanation
The highly exothermic reaction between carbon (coke) and oxygen (hot air blast) produces carbon dioxide and releases a large amount of heat energy, which raises the temperature in the blast furnace.
✅ Answer: (C)
✅ Answer: (C)