Iodimetry (Direct) :-
Titration in which a reducing agent is directly titrated against standard iodine solution are called iodimetry.
In this titration iodine solution is directly involve so iodine solution is available in pure form.
A slightly soluble in water and greatly soluble in aqueos potassium iodide solution due to formation of brown colour potassium triodide (KI3).
I2 + I ---------> I3
KI2 + I ---------> KI3
Indicator :-
Starch is used as a indicator and it gives blue colour.
End Point :-
Starch indicator gives intense blue colour with iodine the appearence of blue colour indicate the end point.
2Na2S2O3 + I2 -----------> Na2SO4O6 + 2NaI
Iodometry (Indirect) :-
The titration in which iodine is liberated in the chemical reaction and then involved in the further reaction are called iodometry titration.
Iodine act as reducing agent and pre- iodine involve titration with standard solution of reducing agent.
KI + Br2 ------------> Kbr + I2
2KI + Cl2 -----------> 2Kc=Cl + I2
