sivas54

The electrolysis could ne carried out in a undivided cell having TSIAnode (Titanium substrate Insolube ANode- CECRI(CSIR)-INDIA)/ or DSA and Titanium or MS cathode. There would not be any appearance of brown colour if the electrolyte around the cathode is buffered (pH: 6.6) properly using K2Cr2O7 (2 gpl). If K2Cr2O7 is present in the electrolyte, there is a great loss of current efficiency. Morover, if we allow formation of brown colured bromine at anode, the anode will get damaged due to the reaction of nascent bromine with the precious metal oxide (Ru, Ir ) catalysts coated on the anodes. The diiference in solubility of KBrO3 at room temeperature and at the cell temperature (60'C) could be used crystallise out the KBrO3. The KBrO3 will be white crystalline salt.

Merged post follows:

Correction: 'If K2Cr2O7 is present in the electrolyte, there is a great loss of current efficiency' should be read as "If K2Cr2O7 is not present in the electrolyte, there is a great loss of current efficiency". bear with me please.- sivas54

Yes. I agree that "molten' is wrong. I apologise for not doing proper editing before placing the reply

The compounds KMnO4, KBrO3, NaBrO3, NaIO3, KIO3 are oxygen liberators. They become explosives if they are dealt with organic alcohol,aldeheyde and ketones. They form explosive mixtures. People should learn the chemistry and chemical reactions of these compounds before handling them with any small lab experiments.

Bromine should be ambuled using borosilicate test tube and a propane plumbing torch. It should not be stored in any bottle with any type of lids. If we do so, the storage enviroment (switch box, fridge ,fan etc all will get corroded. AFter somtime, bromine will be no more in the bottle, but it leaves the effect of corrosion.

Iodine solid could be stored in a brown colour bottle with screwed lids and washers made of flexible plastic ( in gms).

The Iodine solid could be stored by keeping it in sealed high density polythene bag ( in kgs) .

Electrolysis of water could be carried in in undivided cell having stainless anode and cathode and dil sulphuric acid as electrolyte. The electrodes will be of concentric cylindrical design. The oxygen and hydrogen can be collected separately .

In a divided membrane cell, KOH (6M, 80'C) is used as electrolyte, both as anolyte and catholyte. Anode and cathode compartments are separated by a cation exchange membrane.Oxygen and hydrogen gases are collected separately form anode and cathode compartments respectively. Anode may be Nickel/or oxide coated Nickel and cathode is Nickel or coated nickel. Membrane is perfluro sulfonic acid based membrane (Nafion 424 or Nafion 900 series or Nafion 2000)

KMnO4 in neutral aqueous solution is not stable. It slowly gets converted into MnO2. If MnO2 is not filtered out , MnO2 will interfere with all colorimetry expts and also the regular chemical reactions.

Molten lye means hot concnetrated NaOH solution(>30% if from membrane cell or >50% if produced from Mercury cell). It attacks pyrex glass, even MS tanks. container made of Nickel and INCONEL can be used for handling caustic lye