Which of the following statements is true?Metal ions always lose electrons at the cathodeMetal ions always lose electrons at the anodeMetal ions always gain electrons at the cathodeMetal ions always gain electrons at the anode2How is aluminium extracted from the earth?As an aluminium ore known as cryoliteAs an aluminium ore known as bauxiteAs aluminium oxideAs pure aluminium3In the electrolysis of aluminium oxide, the electrodes are made of carbon in the form of graphite. Which of the following statements is not true?The presence of carbon electrodes reduces the amount of energy required for the electrolysis reactionAt extremely high temperatures, the oxygen produced during electrolysis reacts with the carbon anode to form carbon dioxideGraphite is used as an electrode because it is a good conductor of electricityCarbon is relatively unreactive, and the electrodes do not therefore react with the aluminium oxide during electrolysis4Why is molten cryolite mixed with the aluminium oxide prior to electrolysis?To increase the temperature required for the reactionTo hold the electrodes in placeTo act as a conductor of electricityTo lower the temperature required for the reaction5What is the balanced equation for the electrolysis of aluminium oxide?2Al2O3(l) → 3Al(l) + 4O2(g)Al2O3(l) → Al(l) + O2(g)2Al2O3(l) → 4Al(l) + 3O2(g)3Al2O3(l) → 6Al(l) + 3O2(g)

In the electrolysis of aluminium oxide, the electrodes are made of carbon in the form of graphite. Which of the following statements is not true?The presence of carbon electrodes reduces the amount of energy required for the electrolysis reactionGraphite is used as an electrode because it is a good conductor of electricityCarbon is relatively unreactive, and the electrodes do not therefore react with the aluminium oxide during electrolysisAt extremely high temperatures, the oxygen produced during electrolysis reacts with the carbon anode to form carbon dioxide

Which of the following statements about ‘inert’ electrodes is not true?At the cathode, positive ions gain electrons to become metal elementsThey take part in the electrolysis reactionsThey can be made of carbonAt the anode, negative ions lose electrons and become non-metal elements2Copper can be purified by electrolysis using metal (non-inert) electrodes. Which of the following correctly describes how the electrolysis cell should be set up?Cathode should be impure copper, anode should be pure copperCathode should be carbon, anode should be impure copperCathode should be pure copper, anode should be carbonCathode should be pure copper, anode should be impure copper3What happens at the anode?Copper ions formCopper atoms formSulfate ions formImpurities from the impure copper are collected4What happens at the cathode?Impurities from the impure copper are collectedCopper ions formSulfate ions formCopper atoms form5The core practical investigates the changes in electrode mass during the electrolysis of copper sulfate solution at different currents. Which of the following would you not expect to happen?The higher the current the lower the change in mass between the anode and cathodeThe anode decreases in massThe gain in mass by the cathode is the same as the loss in mass by the anodeThe cathode increases in mass6Sometimes the mass gain at the cathode may be slightly lower than the mass loss at the anode. What is an explanation for this?Some of the propanone used in the washing process may not have evaporated properly from the anodeAll of theseSome of the copper deposited at the cathode may have fallen off during the washing processIf the anode is not pure copper, any impurities will be deposited in the electrolyte rather than at the cathode

Aluminium is manufactured by the electrolysis of aluminium oxide dissolved in molten cryolite.At the anode, oxide ions react to make oxygen molecules.Construct the ionic half-equation for this electrode reaction

Which of the following represents the anodic and cathodic reactions during the extraction of aluminium?Anode Cathode(A) 2O2- + 4e →→ O2 AI →→ AI3+ + 3e(B) 4OH- →→ 2H2O + O2 + 4e AI3+ + 3e →→ AI(C) AI3 ++ 3e →→ AI2O2- →→ O2 + 4e(D) 2O2- →→ O2 + 4eAI3 ++ 3e →→ AIA(A)B(B)C(C)D(D)

This question is about electrolysis, extraction of metals, and properties of materials.Describe the process of extracting aluminium from its ore, including the role of cryolite and the reactions at each electrode. Write half equations where appropriate.