[rchok2]

okie heres the procedure

Prepare four test tubes containing respectively 1 drop of i) water, ii)chlorine, iii) bromine and iv) iodine

add 1 drop of iron (II) sulfate solution and 1 drop of 1% potassium thiocyante solution to each test tube; compare the four test tubes (this is to test oxidation of iron(II) to iron(III) - thiocynate ion forms red complex with fe(III))

erm one thing i dun understand is that why is why is iron sulfate added? what is the half equation for each of these?

thx

[oldddog]

As you yourself pointed out, this test is to examine the oxidation of Fe(II) to Fe(III). So you need a source of Fe(II) ions - solution of iron(II) sulfate will provide a relatively stable solution of Fe(II) ions.
REDOX half equations can be found in most general chemistry text books. Do a Google search for redox and half equation will also provide similar information.