Aqueous electrolysis: Chemical Changes: Chemistry: GCSE (9:1)

• Ions in water

  H+ and OH-
• H+ is attracted to

  Cathode
• Discharge of H+

  2H+ +2e- --> H2
• OH- is attracted to

  Anode
• Discharge of OH-

  4OH- --> O2 + 2H2O + 4e-
• Discharged at the cathode in solution

  Least reactive element

  
• Discharged at the anode in solution

  Halide ions, if present, otherwise OH-

  
• Halide ion


  a negative ion formed from a group 7 element

  
• Test for hydrogen

  Lit splint produces a squeaky pop

  
• Metals discharged in preference to hydrogen

  Copper, Silver, Gold, Platinum
• Test for chlorine

  Bleaches damp litmus paper

  
• Test for oxygen


  Relights a glowing splint