1. The chloride ion is oxidized by KMnO4. It's a slow reaction and can be reduced by a few tricks but it causes more KMnO4 to be used than should be used. I'm not sure I would say "seldom used" for there was a time when KMnO4 titrations were quite popular. The use of a Zimmerman-Reinhart solution reduces the effect of the oxidation of chloride ion.
2.I don't know the answer to this question.
3. The brown color is MnO2 which is one of the decay products of KMnO4 and the chief reason why KMnO4 must be standardized fairly often. That's just another way of saying that solutions of KMnO4 are not stable. So the half equation will be KMnO4 ==> MnO2 in neutral solution. I'll leave it for you to balance.
Why are standard KMnO4 solutions are seldom used for the titrations of solutions containing HCl?
2. Why are standard solutions of reductants less often for titrations than standard solutions of oxidants?
3. When a solution of KMnO4 was left standing in a buret for 3 hours, a browning ring forms at the surface of the liquid. Write a balance net equation to account for this observation?
1 answer