practical

• Equipment & Materials:

  • TEST TUBES OR MEASURING CYLINDERS to collect & measure gases produced at the electrodes.
  • ELECTROLYTE SOLUTIONS that will undergo electrolysis.
  • BEAKER to hold the electrolyte during electrolysis.
  • GRAPHITE ELECTRODES that conduct electricity without reacting.
  • POWER SUPPLY to provide a controlled electric current.

  
• Method:

  • Choose an ELECTROLYTE. 
  • Pour out a sample of the electrolyte into the beaker.
  • Immerse two chemically inactive electrodes into the solution & place an INVERTED TEST TUBE over each electrode.
  • Pass CURRENT through the electrolyte & collect the gases in the inverted test tubes or measuring cylinders.
  • Use CHEMICAL TESTS to identify the gases produced.

  
• Label the image:

  A) anode

  B) cathode

  C) electrolyte

  D) test tube

  E) gas collected

  
• Test for Chlorine:


  Add DAMP BLUE LITMUS PAPER to the gas.

  • If the litmus paper BLEACHES WHITE, Chlorine is present.
• Test for Oxygen:


  Add a GLOWING SPLINT to the gas.

  • If the glowing splint RELIGHTS, Oxygen is present.
• Test for Hydrogen:


  Add a LIT SPLINT to the gas.

  • If a SQUEAKY POP is observed, Hydrogen gas is present.
• • concentration / volume of solution was different
  • impurities in solution
  • error in timing
  • copper falls off electrode
  • copper removed when drying electrode
  • electrode not dry when weighted
  • voltage / current was different

  
• Aqueous sodium nitrate, NaNO3

  Observations at anode:

  • Effervescence, no colour, splint relights so gas is oxygen

  Observations at cathode:

  • Effervescence, no colour, squeaky pop, so gas is hydrogen