Seperation of sodium and potassium carbonates

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Discussion Overview

The discussion revolves around the separation of sodium and potassium carbonates from plant ashes, focusing on the solubility of these compounds in various solvents and methods for their separation. Participants explore theoretical and practical aspects of this separation process.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions the solubility of sodium carbonate in ethanol, suggesting that potassium carbonate is not soluble in this solvent.
  • Another participant speculates that sodium and potassium salts may have similar solubility profiles in various solvents.
  • A suggestion is made to use crown ethers for the separation of sodium and potassium carbonates, with a note on the potential need for a strong base to enhance the process.
  • One participant provides specific solubility values for potassium and sodium carbonates in water, raising a question about which would precipitate first in a saturated solution.
  • Concerns are expressed about the cost and toxicity of crown ethers as a separation method.
  • There is skepticism about the presence of carbonates in ashes, with a participant noting that carbonates decompose upon heating.
  • Another participant asserts that both carbonates are indeed present in ashes, with sodium carbonate predominating in sea plants and potassium carbonate in land plants, referencing historical methods of extraction.
  • A later reply acknowledges this point, indicating a correction of earlier skepticism.
  • Discussion includes the idea that oxides or hydroxides formed during burning can absorb CO2 from the air, eventually converting back to carbonates.
  • One participant proposes using an acid reaction followed by separation as a potential method.

Areas of Agreement / Disagreement

Participants express differing views on the solubility of sodium carbonate in ethanol and the presence of carbonates in ashes. While some assert that both carbonates are present, others question this assumption. The discussion remains unresolved regarding the most effective separation method.

Contextual Notes

There are limitations in the assumptions about the composition of plant ashes and the effectiveness of proposed separation methods, as well as the potential for varying results based on specific conditions.

JGM_14
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I want to separate sodium and potassium carbonate from the ashes of plants. My question is, Is sodium carbonate soluble in ethanol? I know that potassium carbonate is not so could i put the mixture into 200 proof ethanol and separate the two?
 
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Only a guess but sodium and postassium salts are going to have very similair solubility in anything.
 
Depending on the composition of your plant ashes, you may want to consider using crown ethers to separate your carbonates; specifically 15-crown-5 for your sodium and 18-crown-6 for the potassium carbonate.

Edit: If it does not interfere with your procedure, consider adding a strong base to deprotonate any groups (e.g., substituted ammoniums) that could otherwise inhibit the ethers' solvation of your cations.
 
Last edited:
Basically, just remember, L S, B C L, S P A
All potassium,nitrate salts are soluble.. however, chlorides,carbonates and sulphates are an exception.For chlorides, all chlorides are soluble except lead chloride and silver chloride..all sulphates are soluble except barium sulphate,chloride sulphate and lead sulphate..for carbonates,sodium,potassium and ammonium carbonate is soluble while the rest are insoluble.. as as sodium and potassium are very reactive when reacted with water due to the reactive series of metals..u can separate sodium and potassium with their solutions by titration, changing them into a oxide or hydroxide...
 
Lucas_SG said:
Basically, just remember, L S, B C L, S P A
All potassium,nitrate salts are soluble.. however, chlorides,carbonates and sulphates are an exception.For chlorides, all chlorides are soluble except lead chloride and silver chloride..all sulphates are soluble except barium sulphate,chloride sulphate and lead sulphate..for carbonates,sodium,potassium and ammonium carbonate is soluble while the rest are insoluble.. as as sodium and potassium are very reactive when reacted with water due to the reactive series of metals.
As sodium and potassium salts have similar solubilities in aqueous solution, consider a solvent that can distinguish between either cation (try crown ethers)
Lucas_SG said:
u can separate sodium and potassium with their solutions by titration, changing them into a oxide or hydroxide...
This makes no sense.
 
Last edited:
Solubility of potassium carbonate is 111 grams per 100 mL of water.
Solubility of sodium carbonate is 30.7 grams per 100 mL of water.
In a saturated solution, which would precipitate out first with careful drying and chilling?

Crown ethers are wicked expensive and toxic as *ell.
 
JGM_14 said:
I want to separate sodium and potassium carbonate from the ashes of plants. My question is, Is sodium carbonate soluble in ethanol? I know that potassium carbonate is not so could i put the mixture into 200 proof ethanol and separate the two?

I ain't real certain carbonates are there in the first place. Not if it's "ashes" as in ashes left over from a fire. Carbonate decomposes with heat to form carbon dioxide. It's why sodium bicarbonate smothers fire.

Somebody correct me if this is wrong.

Jeff Corkern
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Consider the following as a statement of logic and rank it as "True" or "False."

"If people possesses immortal souls, it should be possible to deduce this by logical analysis of their behavior."

www.theninepointfivetheses.blogspot.com
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Ya both carbonates are present in ashes. Na2CO3 predominates in sea plants and K2CO3 in land plants IIRC. This is an old school preparation of potash and is outlined in scores of old textbooks. Use Google books to help you- you'll get more info there than anyone on this forum can give!

--------------------------------
Backyard Chemistry
 
Cesium said:
Ya both carbonates are present in ashes. Na2CO3 predominates in sea plants and K2CO3 in land plants IIRC. This is an old school preparation of potash and is outlined in scores of old textbooks. Use Google books to help you- you'll get more info there than anyone on this forum can give!

--------------------------------

Ah, so.

I stand corrected.
 
  • #10
Even if only the oxided or hydroxides were produced during burning, they absorb CO2 from the air and slowly convert to the carbonates.
 
  • #11
same with calcium oxide
 
  • #12
I wondered how you could form carbonates in a fire . . .


Jeff Corkern
--------------------------------------------------------------------------------------
Consider the following as a statement of logic and rank it as "True" or "False."

"If people possesses immortal souls, it should be possible to deduce this by logical analysis of their behavior."

www.theninepointfivetheses.blogspot.com
--------------------------------------------------------------------------------------
 
  • #13
how about a reaction with an acid then separation
 

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