removing carbon dioxide from sodium carbonate

[the guy]

is there a way of removing carbon dioxide from sodium carbonate without having to react it with anything e.g. by heating it?

[hermanntrude]

yes. exactly. heat it and it will give off carbon dioxide. But it's quite stable up to about 1000°C. Bicarbonate is much easier to decompose.

[the guy]

i was just looking at sodium carbonate on wikipedia and under melting point its says: 851 °C (anhydrous)

100 °C (decomp, monohydrate)

34 °C (decomp, decahydrate)

 

i don't know what monohydrate or decahydrate means, but does that show that if it was in aqueous solution it would decompose at a lower temperature? or am i misunderstanding this?

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and when it decomposes would it decompose to sodium hydroxide?

[CaptainPanic]

Is the carbonate in solution in water?

 

Heating will remove CO2 from the water (gas solubility decreases at higher temperatures).

 

This should influence the equilibrium between CO2 and bicarbonate, and in turn the equilibrium between carbonate and bicarbonate.

 

Monohydrate means that per mol Na2CO3, there is 1 mol water present in the crystal. It's written: [ce]Na2CO3.H2O[/ce]

Decahydrate: [ce]Na2CO3.10H2O[/ce]

 

The presence of water means that a different decomposition reaction is possible.

 

Answer to your last question: I think so (not sure). It will form CO2 and NaOH (please doublecheck)

Edited November 10, 2009 by CaptainPanic

[the guy]

ok, thankyou

[hermanntrude]

the decompositions it's talking about for the monohydrate and decahydrates are their losses of water:

 

[ce]Na2CO3.H2O(s) -> H2O(g) + Na2CO3(s)[/ce]

[ce]Na2CO3.10H2O(s) -> 10H2O(g) + Na2CO3(s)[/ce]

 

In the latter example, probably the sodium carbonate dissolves in its own water as it decomposes. Also it might not lose all ten waters, depending on temperature, pressure etc.