Sciencemadness Discussion Board

Preparing sodium oxylate

textex - 29-3-2011 at 13:01

Hello
I hope this one is in the right place.

Anyways, i need some sodium oxylate for a star comp, i saw that you can prepare it from oxalic acid which is pretty easy to get in a 10-15 solution and NaOH on wikipedia in a 1:2 molar ratio.

I guess that the reaction will go like (CO2H)2 + 2NaOH -> C2Na2O4 + 2H2O that.

Anyways, anyone done it before? Cant find much about it on the net. I guess that the best thing to do would be to make a solution of the NaOH and pour it in?

Random - 29-3-2011 at 14:10

This is simple neutralisation. Mix oxalic acid and NaOH, you will get sodium oxalate.

Though, I wouldn't recommend you messing with pyro compositions without even knowing basic chemistry. I think you don't even know basic things about safety and that could lead you to injuries.



[Edited on 29-3-2011 by Random]

textex - 29-3-2011 at 14:23

Well, i do know some basic chemistry, and i kind of knew how that reaction would be,but im gonna admit i aint that experienced. But incase i missed up on anything its always good to have a second opinion other than my own ;)

And judging what i know or dont know on safety on one post....

Bot0nist - 29-3-2011 at 15:15

I was into amateur pyrotechnics before I really starting amateur chemistry. Both hobbies are dangerous and both can and have killed. As a young teenager I made black powder and flash, and as an adult I enjoy making small rockets and various other little projects like aerial shells and flash pots/fountains. It has been a very fun hobby for me and I have always been able to remain safe by using common sense and learning from the mistakes others have made in the past.

I think the importance of learning as much as one can from before attempting something dangerous relates to chemistry in a more extreme way than even pyrotechnics.

That being said, it doesn't sound like what your wanting to do is that dangerous as long as your not oblivious to to basic lab safety.

Also, if you just need it for your star comps and are not really interested in the chemistry of the salt why not buy it. Its like $15-$20 a pound, but many places won't ship it so you may have a drive.

Random - 29-3-2011 at 15:54

Quote: Originally posted by textex  
Well, i do know some basic chemistry, and i kind of knew how that reaction would be,but im gonna admit i aint that experienced. But incase i missed up on anything its always good to have a second opinion other than my own ;)

And judging what i know or dont know on safety on one post....


Everything is up to you, I just warned you. Though, I am sure it's better to warn someone than giving him information about something dangerous and not warning him. By the way, use stoichiometry for the best results.

woelen - 29-3-2011 at 23:00

I agree with Random. Home chemistry in general involves some risk and pyrotechnics involves much more risk, due to the inherently energetic reactions involved.

I would strongly recommend that you try to understand basic chemistry. First you have to learn walking before you can go running.

This reaction you want to do is a nice example of using basic chemistry knowledge. Suppose I start with 100 grams of oxalic acid, how much NaOH is required to make sodium oxalate? You should be able to answer that question.

In real life things are even more complicated. Do you have anhydrous oxalic acid, or do you have the dihydrate, H2C2O4.2H2O? This is important to know. If you don't know, then you have to find out yourself by carefully neatralizing a solution of known concentration of the acid with a solution of known concentration of NaOH and check how much NaOH is needed to concentrate the solution.

Yet another issue you may encounter is that sodium oxalate is only very sparingly soluble. You need to start off with moderately concentrated solutions of oxalic acid and sodium hydroxide and carefully add the NaOH slowly while stirring. At a certain point Na2C2O4 will separate.

In total you better can have a slight excess of NaOH instead of oxalic acid. Your end product must be absolutely free of acid, otherwise pyrotechnic mixes with it may become dangerously unstable, especially when combined with chlorates (chlorates and acid is a NO GO in pyrotechnics). Your home made material also should be allowed to dry very well in contact with air. If a slight excess of NaOH is used, then it will be hygroscopic, but this property soon disappears if it picks up some CO2 from the air and makes carbonate. Some carbonate in your mix is not bad, it may even help stabilize your composition somewhat.

As you see, there are many things to think about, even when performing such a simple reaction. For this reason I would say: First think, than act!

textex - 30-3-2011 at 06:11

I guess that this would be the calculation for 100g acid:

C2H2O4= 90,03 g/mol

NaOH = 39.99 g/mol

100g / 90,03 = 1,11 * 2 = 2,22 * 39,99 = 88,77 g NaOH

After checking the sources of oxalic acid, the only reasonable price i found is a cleaning agent which contains around 10-15 as stated in the MDS. Pharmacy had a pretty steep price, and i dunno if i feel like ordering it.

And yeah, im considering using it in a chlorate comp, which i know is pretty unstable, especially S*, acids etc. But its not like im planning to make anything out of the first batch i make if i do it.

entropy51 - 30-3-2011 at 09:41

Quote: Originally posted by textex  
After checking the sources of oxalic acid, the only reasonable price i found is a cleaning agent which contains around 10-15 as stated in the MDS. Pharmacy had a pretty steep price, and i dunno if i feel like ordering it.
Hereabouts the hardware stores sell wood bleach which is quite good oxalic acid.