Baking Soda->Sodium Hydroxide?

[recursive]

According to wikipedia, heating sodium bicarb gives you CO2 and sodium carbonate. Also, it says further heating will give you Sodium Oxide and water from thermal decomposition. This means that you should end up with sodium hydroxide.

 

Will this actually work? I couldn't figure out what happened last time I tried because my test tube decided to shatter... I'm pretty sure I got some sort of alkaline solution because me hands felt soapy, like it usually does after handling a base.

 

So...Anyone tried this? Does it actually do this? That would be really convenient!

[YT2095]

Liquid NaOH will attack glass quite badly! should have used a proper Crucible instead.

 

and yes it Really does this (if you can attain the correct temp and for long enough).

[recursive]

Ahh, okay... thanks. By 'proper temperature', what exactly do you mean? Is this a normal flame temperature? I haven't been able to find out exactly how hot a normal 99% ethyl alcohol lamp burns. It certainly gives me tall blue flames, so I guess it would indeed be hot enough.

By the way, why did it turn brown before I finished heating it? I had some extra water in it that I was trying to boil off, and it was intensely brown and moderately viscous. There was a trace amount of iron filings in it, but that probably isn't what caused the brownification of my whatever-it-was.

 

Baking soda is a great source, though. I'm glad it works because I have about a pound of it. I might try to do some electrolysis next. That will be fun!

 

Okay, question: What is a good container to heat this in? Steel? Aluminum?

[John Cuthber]

The bicarbonate will decompose to the carbonate quite easilly. This carbonate is alkaline enough to feel soapy. The carbonate is said to melt at about 850C so presumably, it needs to be hotter than that to decompose it at any sensible rate.

Not only would Al melt before that temperature was reached but it would react with any NaOH produced.

 

I doubt you will get any usefull decomposition of Na2CO3 in home laboratory conditions and it's easy to just buy washing soda.

[Riogho]

I just did something like this today actually

 

I got sodium biocarbonate, and put it into a cute little porcelin pot, and threw a crapload of HCl in there, it of course, reacted, producing water, and carbon dioxide.

[Melvin]

Getting Na2CO3 from baking soda is easy. Simply put the soda into a tin can and place it over high heat. After a couple minutes it will start to "bubble" (It almost looks like blowing air through a layer of sand). When it stops bubbling, it's done. On the other hand, getting Na2CO3 to break down into Na2O and CO2 is very, very hard.

 

However you can make NaOH from Na2CO3. Go to a grocery store and look for "pickling lime." This is Ca(OH)2. (I suggest Mrs. Wages brand because it contains only Ca(OH)2). It's probably around $3-4 dollars for a pound. Make a saturated solution of it and a saturated solution of Na2CO3. When you mix them together, CaCO3 will precipitate and NaOH will remain in solution. Use a coffee filter to seperate out any CaCO3.

 

Na2CO3 + Ca(OH)2 --> 2NaOH + CaCO3

 

Melvin

[Zaire]

and why would you want sodium bicarbonate?

 

or sodium carbonate, or whatever it is that the end result is

[thedarkshade]

According to wikipedia, heating sodium bicarb gives you CO2 and sodium carbonate. Also, it says further heating will give you Sodium Oxide and water from thermal decomposition. This means that you should end up with sodium hydroxide.

I think that the equation looks like this:

[ce] 2NaHCO3 -> CO2 + Na2CO3 + H2O [/ce]

this is part of the Solvay process of getting [ce]Na2CO3[/ce]

[YT2095]

well the MP for Na2CO3 is 858c it decomposes at the BP, but I don`t have a figure for that in my book, but it will be higher than the MP for certain!

 

and probably unlikely to achieve with a plain bunsen burner.

 

I`ll check on that though...

 

thought so, a preliminary figure is 1413c for the BP, Good Luck with that!

 

in addition, if you`re REALLY desperate for NaOH, don`t mess about, just dissolve your carbonate in water and then add calcium hydroxide to it, and then stir well.

 

the PPT that falls will be Calcium carbonate and your soln will be NaOH.

 

saves a load of dicking about!