C4.3.3 - Electrolysis to extract metals

• Why is Electrolysis used to extract metals?

  They are to reactive to be displaced with carbon.
• Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current.
• Aluminium Ore Electrolysis Extraction

  Positive electrodes are used to extract aluminium from bauxite, a white powder. The negative electrode is made of graphite, while the positive electrode is made of aluminium oxide. The negative electrode receives electrons from the negative electrode, reducing aluminium to aluminium atoms. The positive electrodes lose electrons to oxygen gas, forming carbon dioxide. This process requires frequent replacement of positive electrodes, increasing the cost of the process.

  
• Why must the positive electrode be constantly replaced during electrolysis?

  The oxygen reacts with the carbon in the electrodes, forming carbon dioxide which bubbles off. Carbon is therefore lost from the positive electrodes, so they must be replaced frequently. This adds to the cost of the process.