Electrolysis- aqueous solutions

• 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 happen to ions in an electrolyte for electrolysis to work?

  They must be free to move around
• What must be done to insoluble compounds for electrolysis?

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

  By dissolving them in water
• What equipment is needed for an electrolysis experiment?

  A beaker, electrodes, wire, and power supply
• What is the role of the cathode in electrolysis?

  It attracts positive ions
• What is the role of the anode in electrolysis?

  It attracts negative ions
• What ions are present in aqueous solutions during electrolysis?

  Positive and negative ions from the compound and water
• What does the cathode discharge during electrolysis?

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

  Copper ions will be discharged
• What happens at the anode if halide ions are present?

  Halide ions will be discharged
• What happens at the anode if no halide ions are present?

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

  Copper 2+ and sulfate 2- ions
• What will happen at the cathode during the electrolysis of copper sulfate?

  Copper ions will gain electrons and form copper
• What is produced at the anode during the electrolysis of copper sulfate?

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

  Sodium ions, chloride ions, hydrogen ions, hydroxide ions
• What will happen at the cathode during the electrolysis of sodium chloride?

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

  Chloride ions will be discharged
• What are the basic rules for discharging ions at electrodes during electrolysis?

  • At the cathode, the least reactive positive ion discharges.
  • At the anode, if halides are present, they discharge; otherwise, hydroxide discharges.
• What are the steps of electrolysis for copper sulfate solution?

  1. Identify ions: Cu²⁺, SO₄^2-, H⁺, OH^-.
  2. At cathode: Cu²⁺ discharges, forms solid copper.
  3. At anode: OH^- discharges, forms O₂ and H₂O.
• What are the steps of electrolysis for sodium chloride solution?

  1. Identify ions: Na⁺, Cl^-, H⁺, OH^-.
  2. At cathode: H⁺ discharges, forms H₂ gas.
  3. At anode: Cl^- discharges, forms Cl₂ gas.