Sciencemadness Discussion Board

Preparation of sodium sulfite (and other sulfites as well)

glassplass - 28-4-2016 at 11:28

The idea is to buble SO2 gas into the water solution of NaOH.Cause it is hard to add exact ammount of gas it is better to do excess of SO2 and form sodium bisulfite.
The question is,can sodium bisulfite be converted into sulfite by heating and if yes,at wich temperature?
Second question is does that rule aply to all bisufites?

aithecomputerguy - 6-5-2016 at 21:25

You can turn sodium bisulfite into sodium sulfite by adding sodium hydroxide. I don't think it would work with sodium metabisulfite. I'm assuming you know how to calculate the stoichiometery?

gatosgr - 8-5-2016 at 01:48

Where will you get SO2 gas from?

j_sum1 - 8-5-2016 at 02:11

Quote: Originally posted by glassplass  
The idea is to buble SO2 gas into the water solution of NaOH.Cause it is hard to add exact ammount of gas it is better to do excess of SO2 and form sodium bisulfite.
The question is,can sodium bisulfite be converted into sulfite by heating and if yes,at wich temperature?
Second question is does that rule aply to all bisufites?

I have done this. Or more precisely, I was using NaOH to scrub excess SO2 from a reaction. I accumulated a precipitate of Na2SO3 in my flask. It needs recrystallisation for purity but it was a useful byproduct and will suffice for what I use it for.

SO2 was made by burning sulfur. I followed nurdrage's process: https://youtu.be/2gXByJkg0iY?t=3m22s

unionised - 8-5-2016 at 02:52

Quote: Originally posted by aithecomputerguy  
I don't think it would work with sodium metabisulfite.


I do.

aithecomputerguy - 8-5-2016 at 08:32

Quote: Originally posted by unionised  
Quote: Originally posted by aithecomputerguy  
I don't think it would work with sodium metabisulfite.


I do.


I googled it. You're right. I didn't know metabisulfite hydrolysed like that, I've only seen my mother use it to sterilize her wine bottles.

glassplass - 12-5-2016 at 05:23

Soo...The whole process would be like,i buble so much SO2 into the water solution of NaOH,then i have last stage of sulfitation "metabisulfite" in water solution,after that i add some ammount of NaOH solution and make Sodium Sulfite...


[Edited on 12-5-2016 by glassplass]

glassplass - 12-5-2016 at 07:22

Can i make calcium sulfite by bubling SO2 in water solution of calcium hydroxide,or calcium carbonate?
But they are both insoluble in water,would it work efficiently?