Carbonates and bicarbonates: Take about 1g of solid carbonate/ bicarbonate in to a boiling tube and fi x a stopper carrying a delivery tube.

Insert the free end of the delivery tube into about ½ cm height of limewater

in a test tube. Heat the boiling tube. Record any gas evolving and a change in

color of limewater inside the test tube. Note relative time taken to evolve gas. Na2CO3

It will appear as o2(g) as a reactant 

Answerthe half-reaction having the greatest tendency to occur at the anode:     i₂(aq) + 2e⁻  ⇄ 2i⁻  ;   e = +0.53 v======oxidation occurs at the anode. we must therefore find the half-reaction with the greatest tendency to oxidize.the given values of e are reduction potentials (the form of the half-reactions are of reduction).the lower the reduction potential, the higher the potential to oxidize. the half-cell with the lowest reduction potential will have the greatest tendency to oxidize at the anode.the half-reaction having the greatest tendency must be    i₂(aq) + 2e⁻  ⇄ 2i⁻    e = +0.53 vbecause its reduction potential is the lowest out of the three.