electrolysis of aqueous solutions

• what needs to be factored into the solutions?

  the ions from the water, hydrogen ions (H+) and hydroxide ions (OH-)
• what depends on the relative reactivity of all the ions in the solution?


  which ions will be discharged.
• what is produced at the cathode if H+ ions and metal ions are present?


  hydrogen gas is produced if the metal ions form an elemental metal that is more reactive than hydrogen (e.g sodium ions)
• what is produced at the anode if OH- and halide ions (Cl-,Br-,I-) are present?


  molecules of chlorine, bromine or iodine will be formed.
• what is produced when the metal ion forms an elemental metal that is less reactive than hydrogen?


  a solid layer of the pure metal is formed.
• what is discharged and formed when no halide ions are present?

  OH- ions from the water will be discharged and oxygen gas (and water) will be formed
• what does chlorine do to damp litmus paper?


  it bleaches it, turning it white.
• what does hydrogen do with a lit splint?


  hydrogen makes a squeaky pop sound with a lit splint.
• what will oxygen do with a glowing splint?


  relight the splint so the flame is visible again.
• what do half equations do?


  show the reactions at the electrodes (they show ions or atoms gaining or losing electrons)
• what happens when you combine the half equations for the reactions at both electrodes?


  you get the ionic equation for the overall reaction (NUMBER OF ELECTRONS SHOWN IN EACH HALF EQUATION MUST BE THE SAME)