Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Questions regarding NaHSO3 synthesis
Vosoryx
Hazard to Others
***




Posts: 282
Registered: 18-6-2017
Location: British Columbia, Canada
Member Is Offline

Mood: Serial Apple Enjoyer

[*] posted on 13-2-2018 at 21:32
Questions regarding NaHSO3 synthesis


I need some NaHSO3 for an upcoming project, and it needs to be relatively pure. I bought some "pH minus" from the local home depot, and the MSDS says it contains NaHSO3 and Na2SO4. Because I want the sulphite to be relatively pure, my first question is:

1. The sulphate is insoluble in alcohol, and the bisulphite is slightly soluble. (According to pubchem, sites hyperlinked) Would it be practical to wash the mix in MeOH, filter off the sulphate, and then evaporate the solvent off to obtain the bisulphite, or would the purity here be pretty shit? I don't care if there is a lot of loss due to the low solubility, because the raw mix is very cheap, as is MeOH.

2. If that wouldn't work, i'd just do the simple:

SO2(g) + NaOH(aq) = NaHSO3 by bubbling SO2 through an aqueous solution of NaOH, until the pH is neutral. I'd produce the SO2 by adding HCl to the raw mix of pool chemicals.
HCl + NaHSO3 = NaCl + H2O + SO2
Would the purity here be worse? (Perhaps due to the sulphate interfering...?)

Any other comments?

Sorry if the questions are amateur.
Thanks.




"Open your mind son, before someone opens it for you." - Dr. Walter Bishop
View user's profile View All Posts By User
Bert
Super Administrator
*********




Posts: 2821
Registered: 12-3-2004
Member Is Offline

Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".

[*] posted on 13-2-2018 at 23:04


(Edit)

Saw the words "ph minus" and ass-U-Me-D that bisulfate was your interest- As noted, not what you're going to find in that package of swimming pool chemical.

The home brew store has got your Sodium bisulphite.

--------------------

Take a read through this:

http://www.sciencemadness.org/smwiki/index.php/Sodium_bisulf...

.............

[Edited on 14-2-2018 by Bert]
View user's profile View All Posts By User
woelen
Super Administrator
*********




Posts: 8027
Registered: 20-8-2005
Location: Netherlands
Member Is Offline

Mood: interested

[*] posted on 14-2-2018 at 00:13


pH minus does not contain NaHSO3. It contains NaHSO4 (and possibly some Na2SO4).
If you want NaHSO3, then you need to buy Campden tablets for wine making or beer brewing. These tablets can be Na2S2O5 or K2S2O5, which is sulfite with an additional SO2 molecule added to it. In water these form HSO3(-) ions, but also free SO2 is produced. It actually is a complicated equilibrium between S2O5(2-), SO3(2-), HSO3(-) and SO2.

I remember having read somewhere that in the solid phase the HSO3(-) ion does not exist and that on crystallization such solutions form the metabisulfite:

2HSO3(-) --> S2O5(2-) + H2O

I, however, cannot find this written text anymore and other sources talk about sodiumbisulfite or sodium hydrogen sulfite. I myself only have sodium metabisulfite and potassium metabisulfite, both at good purity.

[Edited on 14-2-18 by woelen]




The art of wondering makes life worth living...
Want to wonder? Look at https://woelen.homescience.net
View user's profile Visit user's homepage View All Posts By User
unionised
International Hazard
*****




Posts: 5128
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 14-2-2018 at 01:41


Sodium metabisulphite is sold for home brewing use. It's food grade which implies pretty good purity.

Pool pH reducer is not a sulphite of any sort.

If you give us some details of the upcoming project, we might be able to help you further.
View user's profile View All Posts By User
ninhydric1
Hazard to Others
***




Posts: 345
Registered: 21-4-2017
Location: Western US
Member Is Offline

Mood: Bleached

[*] posted on 14-2-2018 at 15:33


There is a brand of stump remover that isn't KNO3 but sodium metabisulfite, and I feel like sodium metabisulfite is more accessible IMO than NaHSO3.



The philosophy of one century is the common sense of the next.
View user's profile View All Posts By User
Vosoryx
Hazard to Others
***




Posts: 282
Registered: 18-6-2017
Location: British Columbia, Canada
Member Is Offline

Mood: Serial Apple Enjoyer

[*] posted on 14-2-2018 at 17:30


Thanks all - guess I have some more research to do.



"Open your mind son, before someone opens it for you." - Dr. Walter Bishop
View user's profile View All Posts By User

  Go To Top