Electrolysis part 3

• What must happen for electrolysis to work effectively?

  The ions in the electrolyte must be free to move
• What is electrolysis used for?

  To split compounds into their elements
• How is electrolysis performed?

  By passing an electric current through an electrolyte
• What must be done to insoluble compounds for electrolysis?

  They must be melted to form a molten liquid
• How can soluble compounds be prepared for electrolysis?

  By dissolving them in water
• What is the main difficulty in the electrolysis of aqueous solutions?

  Determining which ions will go to each electrode
• What equipment is needed for an electrolysis experiment?

  • A beaker full of electrolyte
  • Two electrodes (positive anode and negative cathode)
  • A wire connecting the electrodes
  • A power supply
• What ions are present in aqueous solutions besides those from the ionic compound?

  Hydrogen ions and hydroxide ions from water
• What does the cathode attract during electrolysis?

  The positive ions from the electrolyte
• What is the rule for discharging ions at the cathode?

  The ion of the least reactive element will be discharged
• What happens if copper ions are present at the cathode?

  Copper ions will be discharged because they are less reactive than hydrogen ions
• What is the equation for the reaction of hydroxide ions at the anode?

  4 OH⁻ → 2 H₂O + O₂ + 4 e⁻
• What is discharged at the anode when hydroxide ions are present?

  Hydroxide ions will be discharged
• What ions are present in an aqueous solution of copper sulfate?

  Copper 2+ ions and sulfate 2- ions
• Which ions will the cathode discharge in an aqueous solution of copper sulfate?

  Copper ions will be discharged
• What is formed at the cathode during the electrolysis of copper sulfate?

  Pure copper accumulates around the cathode
• What happens at the anode during the electrolysis of copper sulfate?

  Oxygen and water are formed from hydroxide ions
• What ions are present in an aqueous solution of sodium chloride?

  Sodium ions, chloride ions, hydrogen ions, and hydroxide ions
• Which ions will the cathode discharge in an aqueous solution of sodium chloride?

  Hydrogen ions will be discharged
• What is discharged at the anode during the electrolysis of sodium chloride?

  Chloride ions will be discharged
• What are the key rules for discharging ions during electrolysis?

  • At the cathode, the least reactive positive ion is discharged.
  • At the anode, if a halide is present, it is discharged; otherwise, hydroxide ions are discharged.