Electrolysis of Aqueous Solutions

• What other molecules do you have to factor in when electrolysing an aqueous solution?

  The water molecules
• What other ions are in an aqueous solutions apart from the ones from the dissolved compound?

  Hydrogen ions (H+) and hydroxide ions (OH-)
• Where will hydrogen be attracted to in an aqueous solutions?

  The cathode
• When is hydrogen produced from electrolysing an aqueous solution?

  If hydrogen is less reactive than the metal ion in the solution
• What happens when metal ions are reduced at the cathode in an aqueous solution?

  They coat the cathode
• When are hydroxide ions discharged and oxygen gas formed in an aqueous solution being electrolysed?

  If there are no halide ions present
• What is a half equation?


  A symbol equation using electrons to show the reactions at the electrodes
• What is the half equation for hydrogen gas at the cathode?

  2H+ + 2e- --> H2
• What is the half equation at the anode when no halogens are present?

  4OH- --> O2 + 2H2O + 4e-