02 - Electrolysis of Solutions

• How do you know which ion will be discharged at the cathode?

  The least reactive ion will always be discharged.
• How do you know which ion will be discharged at the anode?

  If a halide is present, it will always be discharged, otherwise, the hydroxide ion is dicharged.
• What is the half equation for a hydroxide ion being discharged?

  4OH- --> 2H2O + O2 + 4e-
• What can you see at the cathode of copper sulphate solution?

  Pink/orange build up.
• What can you see at the anode of copper sulphate solution?

  Effervescence
• What happens to the colour of copper sulphate solution during electrolysis?

  It goes less blue.
• What can you see at the anode and cathode of hydrochloric acid?

  Effervescence