Sciencemadness Discussion Board

Sodium dichloroisocyanurate + NaOH

nitro-genes - 3-4-2010 at 13:27

Hello,


I hope someone can help me out on this one! :)


When nearly pure sodium dichloroisocyanurate (pool chlorinator) is added to a strong NaOH solution (20 deg. C) a vigorous exothermic reaction ensues, that produces large quantities of a colourless and odourless gas, leaving behind a white precipitate.

Only the filtrate reacts with HCl to produce chlorine gas. My thought would be that the excess NaOH promotes dissociation of the chlorine groups to ClOH, to stabilize as ClO-. No clue about the gas formation and precipitate. Not that I'm an expert in this field anyway! :D

Can someone enlighten me what the gas and precipitate could be?

[Edited on 3-4-2010 by nitro-genes]

Formatik - 3-4-2010 at 23:53

Have you done any qualitative tests on the gas? E.g. bubble it through clear Ca(OH)2 solution (CaCO3 precipitates if it contains CO2), glowing splint test for oxygen, etc.

[Edited on 4-4-2010 by Formatik]

Panache - 7-4-2010 at 09:46

canary in a cage for methane

Formatik - 1-6-2010 at 22:41

Quote: Originally posted by nitro-genes  
Can someone enlighten me what the gas and precipitate could be?


You may have already found the answer by now, but it is N2, CO2 with the CO2 binding to NaOH. Doing the opposite, by adding the base to excess of the dichloroisocyanurate could yield some noxious, hazardous chloramines.

The precipitate is probably sodium cyanurate.

[Edited on 2-6-2010 by Formatik]