Electrolysis of Aqueous Solutions 1

• What should you be able to describe by the end of the video on electrolysis?

  The reactions that take place during electrolysis of an aqueous solution
• What does the term 'aqueous' mean in the context of electrolysis?

  'Aqueous' means dissolved in water
• What ions are formed when water molecules ionize?

  Hydrogen ions and hydroxide ions
• What is the formula for copper sulfate solution?

  CuSO₄ (aq)
• Which positive ions are attracted to the cathode during the electrolysis of copper sulfate solution?

  The copper ion (Cu²⁺) and the hydrogen ion (H⁺)
• How do you determine which ion is reduced at the cathode?

  By comparing the reactivity of the ions to hydrogen
• What happens at the cathode when copper is produced?

  Copper ions gain two electrons to form copper atoms
• What is produced at the anode during the electrolysis of copper sulfate solution?

  Oxygen gas
• What is the general rule for products at the anode during electrolysis of aqueous solutions?

  Oxygen is usually produced at the anode
• What does it mean for electrodes to be inert during electrolysis?

  They do not react with the chemicals being produced
• Why is platinum often used as an electrode?

  Because it is a very unreactive metal
• What is the half equation for the cathode reaction in the electrolysis of copper sulfate?

  Cu²⁺ + 2e^- → Cu
• What is the half equation for the anode reaction in the electrolysis of copper sulfate?

  4OH^- → O₂ + 2H₂O + 4e^-
• What are the key points about electrolysis of aqueous solutions?

  • Electrolysis involves the movement of ions.
  • Positive ions move to the cathode (negative electrode).
  • Negative ions move to the anode (positive electrode).
  • Products depend on the reactivity of the ions involved.
• What should higher tier students be able to do regarding electrolysis?

  • Write half equations for reactions at the cathode and anode.
  • Predict products at the electrodes.
  • Describe reactions during electrolysis of aqueous solutions.
• What is the significance of the reactivity series in electrolysis?

  • Determines which ion is reduced at the cathode.
  • Hydrogen is produced if the metal is more reactive than hydrogen.
  • Helps predict the products formed during electrolysis.
• What does the term 'aqueous' mean in the context of electrolysis?

  Dissolved in water
• What should you be able to describe by the end of the video on electrolysis?

  The reactions that take place during electrolysis of an aqueous solution
• What ions are produced when water molecules split during electrolysis?

  The hydrogen ion H⁺ and the hydroxide ion OH^-
• What is the electrolysis of sodium chloride solution used to demonstrate?

  The reactions at the electrodes during electrolysis
• What are the two ions present in sodium chloride solution?

  The sodium ion Na⁺ and the chloride ion Cl^-
• Which ions are attracted to the cathode during electrolysis?

  The sodium ion Na⁺ and the hydrogen ion H⁺
• How do you determine which ion will react at the cathode?

  By referring to the reactivity series
• What is produced at the cathode when sodium is more reactive than hydrogen?

  Hydrogen gas
• What ions are attracted to the anode during electrolysis?

  The chloride ion Cl^- and the hydroxide ion OH^-
• What is the rule regarding halide ions in an aqueous solution during electrolysis?

  If the solution contains halide ions, the halogen will be produced at the anode
• What gas is produced at the anode during the electrolysis of sodium chloride solution?

  Chlorine gas
• What happens to hydrogen atoms produced at the cathode?

  They immediately pair to form a hydrogen molecule H₂
• How do you write the half equation for the reaction at the cathode?

  H⁺ + e^- → H
• Why do we need to double the half equation for hydrogen production?

  To show the formation of H₂ gas
• What is the half equation for the reaction at the anode involving chloride ions?

  Cl^- → Cl + e^-
• What happens to chlorine atoms produced at the anode?

  They pair to form a chlorine molecule Cl₂
• How can the half equations for the reactions at the cathode and anode be represented differently?

  They can be written in multiple forms but represent the same reaction
• What are the key products of electrolysis of sodium chloride solution?

  • At the cathode: Hydrogen gas (H₂)
  • At the anode: Chlorine gas (Cl₂)
• What are the steps to predict products at the electrodes during electrolysis of an aqueous solution?

  1. Identify the ions present in the solution.
  2. Determine which ions are attracted to the cathode and anode.
  3. Refer to the reactivity series for cathode reactions.
  4. Apply the halide rule for anode reactions.