Electrolysis of Aqueous Solutions

• What ions are present in a solution of copper(II) sulfate (CuSO4)?

  Cu2+, SO42-, H+, and OH-
• Why is copper metal produced at the cathode during electrolysis of copper(II) sulfate?

  Copper is less reactive than hydrogen
• What is the half equation for the reduction of copper ions at the cathode?

  Cu2+ + 2e- → Cu
• What is produced at the anode during the electrolysis of copper(II) sulfate?

  Oxygen gas
• What can be observed at the anode during electrolysis of copper(II) sulfate?

  Bubbles of oxygen gas are produced
• What ions are present in a solution of sodium chloride (NaCl)?

  Na+, Cl-, OH-, and H+
• Why is hydrogen gas produced at the cathode during electrolysis of sodium chloride?

  Sodium is more reactive than hydrogen
• What is the half equation for the production of hydrogen gas at the cathode?

  2H+ + 2e- → H₂
• What is produced at the anode during the electrolysis of sodium chloride?

  Chlorine gas
• What happens to damp litmus paper when chlorine gas is produced?

  It turns white due to bleaching
• What sound does hydrogen make when tested with a lighted splint?

  "Squeaky pop"
• What does oxygen do when tested with a glowing splint?

  It relights the glowing splint
• What are the half equations for the electrolysis of aqueous sodium chloride?

  Negative Electrode:

  • 2H+ + 2e- → H₂
  • 2H+ + 2OH- → H₂ + H₂O

  
  

  Positive Electrode:

  • 2Cl- → Cl₂ + 2e-
  • 2OH- → O₂ + 2e- + H₂O
• What is the ionic equation for the electrolysis of aqueous sodium chloride?

  2H+ + 2Cl- → H₂ + Cl₂
• What happens when a halide is not present in the aqueous solution during electrolysis?

  The anode reaction produces oxygen gas
• What is the process of combining half equations in electrolysis?

  • Ensure the number of electrons is the same
  • Combine the half equations to form the ionic equation
• What is the product at the anode when electrolyzing copper bromide (CuBr₂)?

  Chlorine gas
• What is the product at the cathode when electrolyzing copper bromide (CuBr₂)?

  Copper metal