Electrolysis

• What does electrolysis mean?

  Splitting Up with Electricity
• What happens during electrolysis?

  An electric current passes through an electrolyte
• Where do positive ions move during electrolysis?

  Towards the cathode (-ve electrode)
• What occurs to positive ions at the cathode?

  They gain electrons and are reduced
• Where do negative ions move during electrolysis?

  Towards the anode (+ve electrode)
• What happens to negative ions at the anode?

  They lose electrons and are oxidised
• What does the movement of ions create during electrolysis?

  A flow of charge through the electrolyte
• What do ions form when they gain or lose electrons?

  The uncharged element, discharged from electrolyte
• Why can't anionic solids be electrolysed?

  Because ions are in fixed positions
• Why can molten ionic compounds be electrolysed?

  Because ions can move freely
• What happens to positive metal ions at the cathode?

  They are reduced to the element
• What happens to negative non-metal ions at the anode?

  They are oxidised to the element
• What is required to extract metals via electrolysis?

  High energy to melt the ore
• What ore is aluminium extracted from?

  Bauxite
• What is mixed with aluminium oxide to lower its melting point?

  Cryolite
• What does the molten mixture of aluminium oxide and cryolite contain?

  Free ions that conduct electricity
• What happens to positive aluminium ions at the negative electrode?

  They gain three electrons and become neutral
• What happens to negative ions at the positive electrode?

  They lose two electrons
• What is produced at the cathode during aluminium extraction?

  Aluminium
• What is produced at the anode during aluminium extraction?

  Oxygen
• What is the overall equation for the electrolysis of aluminium oxide?

  2Al₂O₃ → 4Al + 3O₂
• What are the products of electrolysis of molten lead bromide?

  • Lead is produced at the cathode
  • Bromine is produced at the anode
• What is produced at the anode during the electrolysis of molten calcium chloride?

  Chlorine gas
• What is produced at the cathode during the electrolysis of molten calcium chloride?

  Calcium metal
• What is the process of electrolyzing aqueous solutions called?

  Electrolysis of aqueous solutions
• What must be factored in when electrolyzing an aqueous solution?

  The ions in the water
• Why might it be easier to discharge ions from water than from the solute?

  Water ions are more abundant
• What ions are present in aqueous solutions during electrolysis?

  • Hydrogen ions (H⁺)
  • Hydroxide ions (OH⁻)
• What is the reaction that occurs in water during electrolysis?

  H₂O ⇌ H⁺ + OH⁻
• What happens at the cathode during electrolysis if H⁺ ions and metals are present?

  Hydrogen gas will be produced
• What occurs if the metal ions are more reactive than hydrogen?

  Hydrogen gas will be produced
• What happens if the metal ions are less reactive than hydrogen?

  The metal will be deposited
• What is produced at the anode if OH⁻ and halide ions are present?

  Chlorine, bromine, or iodine gas
• What happens if halide ions are not present at the anode?

  Oxygen gas will be produced
• What is the composition of copper(II) sulfate solution?

  Cu²⁺, SO₄²⁻, H⁺, and OH⁻
• How does copper metal compare to hydrogen in terms of reactivity?

  Copper is less reactive than hydrogen
• What is produced at the cathode when copper(II) ions are present?

  Copper metal is produced
• What is the reaction for copper ions at the cathode?

  Cu²⁺ + 2e⁻ → Cu
• What happens if halide ions are present at the anode?

  Chlorine gas will be produced
• What is the reaction for chloride ions at the anode?

  2Cl⁻ → Cl₂ + 2e⁻