Electrolysis

• What is the purpose of electrolysis in metal extraction?

  To extract metals from their compounds.
• Why are metals more reactive than carbon extracted using electrolysis?

  Because they cannot be extracted by reduction with carbon.
• What is the process of extracting aluminium from aluminium oxide using electrolysis?

  • Aluminium oxide is mixed with cryolite to lower the melting point.
  • An electric current is applied to the molten mixture.
  • Aluminium ions move to the cathode and gain electrons to form aluminium.
  • Oxide ions move to the anode and lose electrons to form oxygen.
• What is the melting point of aluminium oxide?

  Approximately 2000°C.
• What role does cryolite play in the extraction of aluminium?

  It reduces the melting point of aluminium oxide.
• What materials are used for the electrodes in the electrolysis of aluminium?

  Graphite.
• Why is graphite used for the electrodes in aluminium electrolysis?

  Because it conducts electricity well and withstands high temperatures.
• What happens to aluminium ions at the cathode during electrolysis?

  They gain electrons to form aluminium atoms.
• What is the half equation for the reaction at the cathode during aluminium extraction?

  Al³⁺ + 3e^- → Al
• What happens to oxide ions at the anode during electrolysis?

  They lose electrons to form oxygen atoms.
• What is the half equation for the reaction at the anode during aluminium extraction?

  O^2- → O + 2e^-
• What occurs to the oxygen atoms formed at the anode during electrolysis?

  • Oxygen atoms pair up to form O₂ molecules.
  • The anode must be replaced regularly due to reaction with oxygen.
• Why must the anode be replaced regularly during electrolysis?

  Because it reacts with oxygen to form carbon dioxide.
• What are the reasons for the high cost of producing metals by electrolysis?

  • High energy required to melt compounds like aluminium oxide.
  • Significant energy needed to produce electric current.
• What is the definition of electrolysis?

  Electrolysis is a chemical process that uses electricity to break down compounds.
• What are the main products of electrolysis in aqueous solutions?

  • Copper at the cathode (if copper ions are present)
  • Oxygen gas at the anode
• What does the term 'aqueous' mean in the context of electrolysis?

  It means that the substance is dissolved in water.
• What ions are formed when water ionizes?

  Hydrogen ions (H⁺) and hydroxide ions (OH^-).
• What ions are present in copper sulfate solution during electrolysis?

  • Copper ions (Cu²⁺)
  • Sulfate ions (SO₄^2-)
  • Hydrogen ions (H⁺)
  • Hydroxide ions (OH^-)
• How do you determine which ion is reduced at the cathode during electrolysis?

  The ion that is less reactive than hydrogen is reduced at the cathode.
• What is produced at the cathode when copper sulfate solution undergoes electrolysis?

  Copper is produced at the cathode.
• What gas is produced at the anode during electrolysis of aqueous solutions?

  Oxygen gas is produced at the anode.
• What is the role of inert electrodes in electrolysis?

  • They do not react with the chemicals produced.
  • They provide a surface for the reactions to occur.
• What is the main focus of the lesson on electrolysis of aqueous solutions?

  To describe the reactions during electrolysis and predict products at the electrodes.
• What is a common material used for inert electrodes?

  Platinum is often used as an inert electrode.
• What happens to copper ions at the cathode during electrolysis?

  They gain two electrons to form copper atoms.
• What does the term 'aqueous' mean in the context of electrolysis?

  Aqueous means dissolved in water.
• What is the half equation for the reaction at the cathode during electrolysis of copper sulfate?

  Cu²⁺ + 2e^- → Cu.
• What ions are produced when water molecules split during electrolysis?

  • Hydrogen ion (H+)
  • Hydroxide ion (OH-)
• What are the two ions present in sodium chloride solution?

  Sodium ion (Na+) and chloride ion (Cl-).
• What is the half equation for the reaction at the anode during electrolysis of copper sulfate?

  4OH^- → O₂ + 2H₂O + 4e^-.
• What is the significance of the reactivity series in electrolysis?

  • Determines which ion will react at the electrodes
  • Helps predict whether hydrogen or a metal will be produced at the cathode
• What is the significance of half equations in electrolysis?

  • They represent the reduction and oxidation reactions.
  • They help in understanding the electron transfer process.
• What determines whether hydrogen or sodium is produced at the cathode during electrolysis?

  Hydrogen is produced because sodium is more reactive than hydrogen.
• What is produced at the anode when the aqueous solution contains halide ions?

  • The halogen corresponding to the halide ion is produced.
  • Example: Chlorine gas is produced from chloride ions.
• What gas is produced at the cathode during the electrolysis of sodium chloride solution?

  Hydrogen gas (H2).
• What is the general outcome of electrolysis in aqueous solutions?

  Electrolysis in aqueous solutions typically produces a metal at the cathode and oxygen at the anode.
• What gas is produced at the anode during the electrolysis of sodium chloride solution?

  Chlorine gas (Cl2).
• What is the reduction reaction occurring at the cathode during electrolysis?

  • Hydrogen ion (H+) gains an electron to form hydrogen atom (H).
  • Hydrogen atoms pair to form hydrogen molecule (H2).
• How can the half equation for the reaction at the cathode be represented?

  H+ + e- → H, then doubled to show H2 formation.