electrolysis

• what is the aim of this practicle?


  determine the products made when a current is passed through a salt solution
• step 1 :

  place carbon electrodes (inert) in a solution of the salt to be electrolysed, ensuring they dont touch. connect to the terminals of a battery or a (DC) power supply.
• step 2 :

  the solution contains H+ and OH- ions, if a sodium chloride solution is being used then there will also be Na+ and Cl- ions
• step 3:

  if the metal is more reactive than hydrogen (like sodium) it will stay in solution and hydrogen will be reduced at the cathode to make H2 gas. if not the metal will be reduced
• step 4:

  if the non metal ion is a hallide (chlorine, bromine, iodine), it will be oxidised at the anode (Cl2 will be made here- proven by bleaching litmus paper). if its not a hallide oxygen gas will be made at the anode instead