RP8

• Rubbing aluminium with sandpaper

  To remove the oxide layer
• A simple salt bridge can be prepared by dipping a piece of filter paper into potassium carbonate solution
• Hydrochloric acid reacts with carbonate ions

  2H+ + CO32- --> H2O + CO2
• Aluminium ions react with carbonate ions

  2Al3+ + 6CO32- --> Al(OH)3 + 6CO2
• Measure the EMF of an electrochemical cell

  1. Clean a strip of copper metal and a strip of zinc metal with emery paper

  2. Place the copper in a 100cm3 beaker containing 50 cm3 1 mol dm-3 copper sulfate solution

  3. Place the zinc in a 100cm3 beaker containing 50 cm3 1 mol dm-3 zinc sulfate solution

  4. Join the two beakers with a strip of filter paper saturated with sodium chloride solution

  5. Connect the Cu(s)|Cu2+(aq) and Zn(s)|Zn2+(aq) half-cells by connecting the metals using crocodile clips and leads to the voltmeter and read off the voltage
• Daniell cell


  Uses copper and zinc
• Write the conventional representation of a Zn/Zn2+ and Cu2+/Cu cell

  1. Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)

  2. Eo = +1.10 V

  Electrons flow from Zn electrode (negative and oxidised) to Cu2+ (positive and reduced)

  RHS (reduced) - LHS (oxidised)
• Salt bridge


  • Allow movement of ions between electrodes
  • Must not react with the electrolyte / ions in solution