Sodium Carbonate

mrred · Oct 25, 2013

I just ran out and need some quick. If I bake "baking soda" in the oven (450F 4 hrs), do I get mono or anhy?

pdeeh · Oct 25, 2013

Ian C · Oct 25, 2013

Sodium carbonate monohydrate, 55 ounces (1.56 Kg) for $3.24 in the US. It’s priced similarly in Canada.

http://www.walmart.com/ip/Arm-Hamme...gent-Booster-Household-Cleaner-55-oz/19407690

http://www.sfm.state.or.us/CR2K_SubDB/MSDS/ARM_&_HAMMER _SUPER_WASHING_SODA.PDF

mrred · Oct 25, 2013

pdeeh said:
anh

Thanks.

mrred · Oct 25, 2013

Ian C said:
Sodium carbonate monohydrate, 55 ounces (1.56 Kg) for $3.24 in the US. Its priced similarly in Canada.

http://www.walmart.com/ip/Arm-Hamme...gent-Booster-Household-Cleaner-55-oz/19407690

http://www.sfm.state.or.us/CR2K_SubDB/MSDS/ARM_&_HAMMER _SUPER_WASHING_SODA.PDF

Good to know, but I needed it now....and I had a box of baking soda on the shelf.

Gerald C Koch · Oct 25, 2013

mrred said:
I just ran out and need some quick. If I bake "baking soda" in the oven (450F 4 hrs), do I get mono or anhy?

Two hours at 350F should be sufficient. Remember to stir it several times during the process. Also use a SS, agate ware or glass baking pan, do not using aluminum. Use a pan with a large surface area for better results. The baking soda will change appearance from a fine crystalline powder to a fluffy, very light weight powder.

dmb · Oct 25, 2013

If you bake at 450F (230C) or even 350F it will be anyhydrous as it comes out of the oven. It will then gradually absorb atmospheric water to become monohydrate. So put it in a sealable tin/jar while still hot and let it cool in there.

mrred · Oct 25, 2013

I used aluminum foil on a large cookie sheet, as it is also easier to pour into a container. Stirred and not shaken....

I used a higher temp and a longer time because the last batch I made (years ago) I should have fired the QA Inspector (me). I only got around to using it this summer, and it was quite dead. It was made long enough ago, I don't remember what I did or did not do.

ntenny · Oct 25, 2013

It sounds like the crisis is resolved, but in my experience it's probably quicker to run to the store than to cook down the baking soda. Your milea^H^H^H^H^Hkilometrage may vary depending on where your store is, of course.

The "pH-up" stuff sold for hot tubs and swimming pools is sodium carbonate as well. Washing soda seems to be getting harder to find.

-NT

fotch · Oct 25, 2013

Gerald C Koch said:
.. do not using aluminum. U.

Just curious, why not aluminum?

john_s · Oct 25, 2013

ntenny said:
.......The "pH-up" stuff sold for hot tubs and swimming pools is sodium carbonate as well. Washing soda seems to be getting harder to find.

-NT

Swimming pool supplies can be rather impure. I bought something once (not sodium carbonate I should add) and it said on the bag "83% pure." It did the job.

Gerald C Koch · Oct 26, 2013

fotch said:
Just curious, why not aluminum?

Aluminum is a highly reactive metal. It is usually prevented from reacting by a thin oxide film on the surface. A classic chemistry demonstration is to remove this protective oxide coating. When so treated aluminum will displace hydrogen from water just like sodium, potassium or calcium metal. The sodium carbonate and steam formed during the heating may attack an aluminum pan and also contaminate the sodium carbonate producted.

Gerald C Koch · Oct 26, 2013

The advantage in using baking soda is that it is USP grade and very pure. Commercial sodium carbonate used to adjust pool pH usually is contaminated with iron. The iron can cause problems with ascorbate developers.

mrred · Oct 26, 2013

Outside of using aluminum foil, there is no downside to making it yourself then?

I opted to use the foil initially because the tray had been used for baking and had all the normal "stuff" left on it from normal use. I guess I will have to get some "his" pyrex then.

Sodium Carbonate

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