Author Topic: Making Sodium Carbonate from Baking Soda (and making electrolyte)  (Read 348 times)

Offline rogwhat53

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1) In the article. "Making Sodium Carbonate from Baking Soda" it is stated:

"This washing soda weighs 8.4 to 9.2 grams per level tablespoon, so to make 1 Molar sodium carbonate solution, add enough distilled water to 1 level tablespoon to make 3 ounces of liquid.  This is close enough if you have no graduated cylinder and scale."

If the density of anhydrous Na2CO3 = 2.54g/cc  (https://en.wikipedia.org/wiki/Sodium_carbonate), and,

14.8 ml/tbsp (https://www.google.com/search?hl=en&gbv=2&q=ml+in+a+tablespoon&oq=ml+in+a+tablespoon&aqs=heirloom-srp..0l5),

then, 14.8 cc/tbsp x 2.54 g/cc = 37.6g/tbsp

Yet the article above says 8.4 to 9.2 grams per tablespoon..... ???


2) If the article had said 1 teaspoon (4.93 cc/tsp), and enough water to make 4oz fluid, that would be:

4.93 cc/tsp x 2.54g/cc = 12.5g, which in 4 oz is 12.5g  x (33.8oz/L)/(4 oz)= 105.8g which is one molar solution.

So I am guessing that one teaspoon is intended instead of one tablespoon?

rogwhat53

Offline wgpeters

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Re: Making Sodium Carbonate from Baking Soda (and making electrolyte)
« Reply #1 on: March 25, 2020, 09:09:00 PM »
I just weighed a level teaspoon of anhydrous sodium carbonate on two separate scales at 2.3 grams, which is way less than what you state.  So a tablespoon should weigh 6.9 grams, and the amount of water for a 1M solution would be 65ml.

I suggest the best thing is to weigh your electrolyte.  The density of a powder depends on the granule size and how it is packed.  If it were one solid crystal, it would have a higher density.


« Last Edit: March 25, 2020, 09:27:09 PM by kephra »
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Offline rogwhat53

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Re: Making Sodium Carbonate from Baking Soda (and making electrolyte)
« Reply #2 on: March 25, 2020, 10:08:13 PM »
I was only using online sources (and I checked several for corroboration) but I agree the direction of your measurement of the mass of one tsp of Na2CO3 even though I measured 53grains/15.4grain/gram = 3.44grams of Na2CO3 per teaspoon instead of your 2.3grams. I see in the Wikipedia data on Na2CO3 that the density changes dramatically whether it is anhydrous or not.....

So I am confused. I wonder if the baked anhydrous is becoming "hydrous?"

I put 12.5grams of baked Na2CO3 in 2 oz of water for a 2molar solution (2 x 106gram x 2/33.8 = 12.5gram) which I used 1/2mL (12 drops applied to a Liter, out of a measured 24drops per gram of H2O).

Using a reloading powder scale (1gram = 15.4grain, and 0.1grain resolution) is, I hope, much "more better" than using a volumetric level teaspoon or level tablespoon measure and questionable online conversions, as I was doing before last night.


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Offline wgpeters

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Re: Making Sodium Carbonate from Baking Soda (and making electrolyte)
« Reply #3 on: March 25, 2020, 10:17:22 PM »
Absolutely your powder scale would be more accurate. 

Yes, once you bake the baking soda, it will absorb moisture from the air and become heavier.  Keep it sealed in an airtight bottle. 
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Offline rogwhat53

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Re: Making Sodium Carbonate from Baking Soda (and making electrolyte)
« Reply #4 on: March 26, 2020, 04:13:39 AM »
I just made inside diameter and depth measurements on my volumetric “level teaspoon” measure, and on a matching level tablespoon measure. Ignoring a slight chamfer in the wall-to-bottom corner of each, I calculate 4.9cc for the teaspoon and 15.3cc for the tablespoon.

Online sources give 4.93cc and 14.7cc, respectively, so that’s pretty close.

Your weighed teaspoon of anhydrous Na2CO3 would have a mass density of 2.3g/4.9cc = 0.47 g/cc. But numerous online sources say the density of anhydrous Na2CO3 is 2.54g/cc.

I understand your point about the effective density of a powder vs a single crystal, but  that is very dramatic difference and it leads me to question recipes I have seen and used employing the volumetric measure......

My own level teaspoon of my baked-soda Na2CO3 was (59.0grains)/(15.4grain/gram) = 3.83gram for a density of .78 g/cc.

I will assume that a cooling time of the order of one hour between end of bake cycle and the weighing of Na2CO3 is not enough time for anhydrous to become significantly hydrous?

This is confusing me..... I am not sure I have done everything right.

rogwhat53

Offline rogwhat53

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Re: Making Sodium Carbonate from Baking Soda (and making electrolyte)
« Reply #5 on: March 26, 2020, 05:37:41 AM »
wgpeters,

at this link:
https://www.binmaster.com/_resources/dyn/files/75343622z9caf67af/_fn/Bulk+Density.pdf
Soda Ash (Sodium Carbonate) is assigned a bulk density of 0.88g/cc.

this link:
http://www.anval.net/downloads/bulk%20density%20chart.pdf
gives 865 kg/m^3 = 0.865g/cc bulk density for Soda Ash.

That's a good term, "bulk density," to denote the difference between a powder and a single crystal, which was a central point of your last reply. I was ignorant of this distinction, but now think this difference between "density of a crystal" vs "bulk density of a powder" is at the root of how I originally miscalculated a molar quantity measured with a volumetric teaspoon.

That mistake is now corrected by having used a powder scale to mix a new and hopefully correct batch of electrolyte.

Thank you for pointing me in the right direction!

rogwhat53