havarti_gouda
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sodium bisulfite from sodium bisulfate
In my recent work with +O/-Hing primary and secondary alcohols to their respective aldehydes and ketones, I've been investigating the usage of sodium
bisulfite in forming the bisulfite adduct for isolation and purification. Obviously, when simply oxidizing the alcohols, I probably wouldn't need to
form the bisulfite adduct as there are few other fractions in the solution, so it's more for education than necessity.
While it tends to be a lot easier to just order the necessary supplies, I find that from an educational perspective, I can learn a lot more about
their properties and various chemical reactions by attempting to generate them.
In this case, I'm looking to start from sodium chloride or sodium hydroxide. I was reading about yielding sodium bisulfate from sodium hydroxide and
sulfuric acid or sodium chloride and sulfuric acid at elevated temperatures. First of all, what molar ratio would be necessary to yield sodium
bisulfate instead of sodium sulfate? I imagine sodium hydroxide would be more ideal. Furthermore, to go from NaHSO4 to NaHSO3 is where I'm really
running into problems. What would be an appropriate reducing agent to remove the one oxygen molecule?
Any help would be greatly appreciated! Thanks in advance.
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entropy51
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| Quote: | | While it tends to be a lot easier to just order the necessary supplies, I find that from an educational perspective, I can learn a lot more about
their properties and various chemical reactions by attempting to generate them. |
You would be amazed at the
educational value of reading a chemistry book before you attempt to "generate" them.
| Quote: | | First of all, what molar ratio would be necessary to yield sodium bisulfate instead of sodium sulfate? |
If
you can't manage to read a chemistry book, at least post these silly questions in the short questions thread. This is basic high school chemistry.
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havarti_gouda
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I am guessing that people with a genuine interest and desire to learn are horribly offensive or something.
I spent about 30 minutes reading through a number of text books and looking online before posting my question. Maybe I was using the wrong terminology
(reducing sulfates to sulfites, sulfate reduction, reduction of sulfates to sulfites). I'm not looking for a step-by-step explanation, just a point in
the right direction that is slightly more specific than "read a textbook, douche bag."
I guess the most helpful part of your response was suggesting I post in another section, but I didn't realize this was so basic as there are other
questions I've seen in this section which appear more basic than this and informative responses followed. Sorry about that.
Rather than flaming me again, perhaps you could just suggest a couple of topics that I could look into that would point me in the right direction?
Certainly you are knowledgeable enough to do so. I'll be sure to post in the beginners section in the future. Thanks. :-)
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DJF90
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Perhaps you shouldn't have your heart set on the reduction of sulfates. Try looking for "preparation of sodium bisulfite" or "sodium bisulfite
preparation". The large inorganic textbook by Brauer in the forum library I think will be much use to you.
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havarti_gouda
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Thank you very much!
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woelen
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The question of the ratio of NaOH and H2SO4 needed to make NaHSO4 indeed is a very basic one. You simply take these chemicals in a 1 : 1 molar ratio.
It might be an interesting exercise for you to convert this to grams. H2SO4 usually is 96% and has a density of 1.84 gram/ml, so another nice exercise
is to convert to ml. If I ask you, given 100 grams of NaOH, how many ml of 96% H2SO4 would you need to convert it to NaHSO4?
Btw, if you really intend to perform the reaction between NaOH and H2SO4, be very careful, this is a very exothermic reaction so please do not mix 100
grams of NaOH at once with the correct amount of H2SO4!!
The other question of going from NaHSO4 to NaHSO3 is of another order. First, NaHSO3 does not exist in the solid state, the bisulfite ion HSO3(-) only
exists in aqueous solution. When an attempt is made to crystallize the salt from such a solution, then Na2S2O5 (sodium metabisulfite) is obtained and
almost certainly also some SO2 is lost leaving Na2SO3 behind. But you won't even come this far, the sulfate ion (or bisulfate ion) is very hard to
reduce to sulfite (or bisulfite). Sulfate ion can be reduced (e.g. bij zinc metal), but then you get all kinds of sulphur-containing compounds
(sulfide, sulfite, and a plethora of thionate ions). So, forget about going from NaHSO4 to NaHSO3 (or better: Na2S2O5). Sodium metabisulfite or
potassium metabisulfite, however, easily can be purchased, it is one of the few chemicals which still is not under suspicion. The potassium salt can
be purchased at wine makers shops and the sodium salt at online shops for raw photography chemicals.
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havarti_gouda
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Na = 22.989770
H = 1.00794
S = 32.066
O = 15.9994
NaHSO4 = 120.06131
NaOH = 39.99711
H2SO4 = 98.07948
100gram of NaOH = 2.5001M of NaOH
2.5001M of H2SO4 = 245.208507948
.96(1.84) = 1.7664g/mL
~139mL of 96% H2SO4 per 100g of NaOH
I hope I did that right :-)
Well, that certainly explains things. I've actually just gone ahead and followed your advice and just ordered some sodium bisulfite (i'm assuming in
aq. form) from a photo supply shop along with a couple other things I was wrestling with -- HOAc, NH4NO3, etc.
Thanks!
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woelen
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Yes, your computation is right. You see, it is not difficult at all.
Good that you ordered some of these basic (and interesting) chemicals. The "sodium bisulfite" most likely will be a white solid, but what you'll
receive is sodium metabisulfite. Unfortunately many people, including suppliers, use the wrong name for the metabisulfite.
For the type of computations, given here, this may be interesting for you:
tutorial: http://woelen.homescience.net:18080/chemeq/tutor/tutor.html
calculator: http://woelen.homescience.net:18080/chemeq
Reading the tutorial also may be interesting for you from a theoretical point of view, some theory about balancing of equations is given and it is
shown that not all equations can be balanced unambiguously.
[Edited on 28-1-10 by woelen]
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havarti_gouda
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I don't really understand how to properly balance equations and why certain molecules are attracted to other ones. I'll be sure to read up on that
before asking any questions. :-) I understand some very very basic principles of acid/base and accepting or donating protons and electrons and
something to do with two methods of thought regarding that, Lewis and someone else, but that's about it. Maybe I understand more than I think I do and
terminology is getting in the way, but I plan on investigating those topics asap due to principles being so core in everything I've been working with
so far.
Oh okay. Yeah, they have both sodium bisulfite and sodium metabisulfite for sale on the site. I was under the impression both could be used rather
interchangeably in relation to forming a bisulfite adduct, but was confused as to other differences. Thanks for the information!
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Vogelzang
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sodium bisulfate + sodium sulfite --> sodium sulfate + sodium bisulfite
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entropy51
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| Quote: | | I don't really understand how to properly balance equations |
Yes, that was my point. I wanted you to
realize that you really must learn this important skill, and preferably before you start mixing chemicals. I also wanted
you to think about the wisdom of posting before you have gone as far as you can on your own, with a good textbook. If you had posted balanced
equations for what you wanted to do, it would have shown that you were trying to think the problem through.
In short, you won't learn very much if we just give you the answers.
[Edited on 28-1-2010 by entropy51]
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havarti_gouda
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@entropy51:
While it seems you certainly have good intentions, your means of expressing them came off as insulting and holier-than-thou. I realize that balancing
equations is one of the most basic foundations of chem theory, but by "mixing up chemicals," I'm not only learning a great deal hands-on, but I'm
having a lot of fun. For the first time in years, I've found a hobby that sparks my interest like ether on an open flame. Speaking of which, I have
indeed read a number of chapters relating to laboratory safety and proper procedures when working with chemicals of any type.
In all fairness, I completely understand what you're saying about how posting the equation would suggest that I'm thinking it through. While I
certainly attempt to do and learn as much on my own before posting, I've learned such a massive amount just from staying up on these forums. I realize
that not everything posted is 100% accurate and I definitely do additional research before attempting anything I've read about anywhere.
I'll be sure to read up on balancing equations this weekend so in any future posts I can include such data. Thanks!
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entropy51
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| Quote: | | I'll be sure to read up on balancing equations this weekend so in any future posts I can include such data. Thanks! |
I'm sorry I was a little harsh. I'm very glad that you've found such a strong interest in chemistry, but remember that chemistry is
about 90% thinking and reading and only 10% lab work. My feelings aren't hurt and I hope yours aren't either.
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Mr. Wizard
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The love of the exotic colors, strange flames, magnets, crackling electrical arcs, sounds coming from a box, and glowing vacuum tubes started my
interest in science. I know it has done the same for many others. After reading this I found it was also a common denominator with the atomic
scientists working on a nuclear devices. Maybe it was standing in my parents backyard in the early 1950s and watching atomic bombs light up the dawn
sky to the north.
http://makezine.com/images/07/strangelove.pdf
Another interesting read is "Diary of a Pyro" at this link.
http://www.armory.com/~spcecdt/pyrotech/doap/
You have to be interested to get involved. To get involved you have to get away from your computer and really do something, usually many times
unsuccessfully, before getting the satisfaction of a success.
Always keep learning, it gives you more cards and options to play in the game of life.
Attachment: Strange Love-Dyson.pdf (449kB)
This file has been downloaded 503 times
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CaptainPike
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solid sodium bisulfite? vs aqueous sodium pyrosulfite
…I'm reviving this old thread (obviously)
Because I'm really confused now. Most of the stuff has to go on in my head (the organic, organic lab).
So when sodium bisulfite is called for, as in, to remove unwanted aldehydes, is an aqueous solution of the salt implied? Is there ever sodium
bisulfite salt, in solid form?
And also what about… doesn't
Na2S2O5 + H2O --> 2 NaHSO3?
Can the "pyro" salt be used (500 mmol scale) ? IE could sodium meta-bisulfite be used to clean up an aqueous solution containing unwanted aldehydes?
I'm having some déjà vu on this.
Oo… A very cool moon is rising! [7:12 PM EST]
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