electrolysis

• What is an electrolyte?

  An electrolyte is a liquid or solution that contains an ionic compound with free-moving ions.
• How do we prepare an electrolyte from a soluble ionic compound like copper sulfate?

  We dissolve it in water to create an aqueous solution.
• What must we do to prepare an electrolyte from an insoluble ionic compound like lead bromide?

  We must melt it to obtain a molten liquid.
• What ions are present in molten lead bromide?

  Positive lead ions and negative bromide ions.
• What are the electrodes used in electrolysis generally made of?

  They are generally made of metal or carbon.
• What is the positive electrode called?

  The positive electrode is called the anode.
• What is the negative electrode called?

  The negative electrode is called the cathode.
• Why do we need a power supply in electrolysis?

  We need it to drive the flow of electrons between the electrodes.
• What does the term electrolysis literally mean?

  It literally means splitting up with electricity.
• What happens to the negative bromide ions during electrolysis?

  They are attracted to the positive anode and are discharged to form bromine gas.
• What occurs when bromide ions are discharged at the anode?

  They go from charged ions to neutral atoms and pair up to form bromine gas.
• What happens to the positive lead ions during electrolysis?

  They are attracted to the negative cathode and are discharged to form pure lead.
• What is the result of the discharge of lead ions at the cathode?

  It results in the formation of pure lead, which falls to the bottom as a layer of molten lead.
• What is happening to the ions at the electrodes during electrolysis?

  The ions are being oxidized and reduced at the electrodes.
• What happens to bromide ions at the anode during electrolysis?

  They are oxidized to bromine and lose one electron each.
• What happens to lead ions at the cathode during electrolysis?

  They combine with two electrons and are reduced to form pure lead.
• How are electrons transferred during the electrolysis process?

  Electrons from the bromide ions are passed to the positive anode and then transported to the cathode.
• What is the overall purpose of electrolysis in this context?

  It is to convert the ions in a compound back into their pure elemental forms.
• What are the steps involved in the electrolysis of molten lead bromide?

  1. Prepare molten lead bromide as the electrolyte.
  2. Connect the electrodes (anode and cathode).
  3. Apply a power supply to drive the flow of electrons.
  4. Negative bromide ions move to the anode, get oxidized to bromine gas.
  5. Positive lead ions move to the cathode, get reduced to form pure lead.
• What process is used to extract reactive metals from their oxides?

  Electrolysis
• Why do metals often exist as oxides?


  Because they react with oxygen in the environment
• What is the purpose of reducing the metal in the oxide?


  To remove the oxygen and isolate the pure metal
• What is the cheap and easy way to reduce metal oxides?


  Reduction with carbon
• Which metals can be reduced using carbon?

  Zinc, iron, and copper
• Why is electrolysis more expensive than reduction with carbon?

  Because it requires a lot of energy
• What is the process of electrolysis?

  Separating ionic compounds into their pure elements by passing an electric current through an electrolyte
• What is required for electrolysis to work?

  The ions must be able to move
• Why can't aluminium oxide be used directly for electrolysis?

  Because it is solid and the ions are fixed in place
• What is the first step in preparing aluminium oxide for electrolysis?

  Purifying the aluminium oxide from bauxite
• What mineral is mixed with aluminium oxide to lower its melting point?


  Cryolite
• What is the melting point of aluminium oxide?

  Over 2000 degrees Celsius
• What equipment is needed for the electrolysis of molten aluminium oxide?

  A beaker, two carbon electrodes, and a power source
• What are the two types of electrodes used in electrolysis?

  Anode and cathode
• What happens to the oxygen ions at the anode during electrolysis?


  They transfer their electrons and are discharged as oxygen atoms
• What is produced at the cathode during electrolysis of aluminium oxide?

  Molten aluminium metal
• What is the half equation for the reaction at the anode?

  Oxygen ions going to form oxygen atoms plus electrons
• What mnemonic helps remember the difference between oxidation and reduction?

  Oil rig (oxidation is loss, reduction is gain)
• What is the overall equation for the electrolysis reaction of aluminium oxide?


  Aluminium oxide (liquid) goes to aluminium (liquid) and oxygen (gas)
• What are the steps involved in the electrolysis of aluminium oxide?

  1. Purify aluminium oxide from bauxite
  2. Mix with cryolite to lower melting point
  3. Melt the mixture to create molten aluminium oxide
  4. Set up electrolysis equipment with electrodes and power source
  5. Conduct electrolysis to produce aluminium and oxygen
• What happens at each electrode during the electrolysis of aluminium oxide?

  • At the anode: Oxygen ions lose electrons and form oxygen gas
  • At the cathode: Aluminium ions gain electrons and form molten aluminium