[ifuller]

Hey,
I have a question if anyone wants to answer. I have solid citric acid (C6H8O7). I added a small amount of this powder to regular tap water and noticed some mild bubbling. I thought that there would not be a chemical reaction, that the acid would simply dissolve in the water. Any ideas on what reaction is going on and what the bubbles are? Thank you for any help.

[pizza1512]

Well, citric acid is a weak acid so I also assumed that the C₆H₈O₇ would just simply dissolve in water.

According to Wikipedia it seems that Citric Acid actually crystallises from reacting with water.  However I am uncertain to why the reaction bubbled.... 

[Borek]

It is weak, but not that weak - it should lower pH substantially. The only idea I have is carbon dioxide. Is your water hard?

[ifuller]

The water is not extremely hard. I have a water softener but am not sure as the the exact content of the water. When the powder is first added bubbles are produced from the powder water combination. After this initial reaction bubbles form on the sides of the containers but do not rise to the surface. Any ideas as the why this is happening?

Thanks

[Borek]

Is it happening with the same water after it is boiled?

[ifuller]

I do not know. I haven't tried boiling the water first. Are you thinking that this will rid the water of most impurities? Thanks

[Borek]

Gas that you see is most likely either CO2 or N2, O2. Boiling will remove N2, O2 and (at best) half CO2. Second half of CO2 will be still ready to bubble out in the presence of citric acid.

[ifuller]

Thanks for all the information and help. Why are there gasses being liberated such as nitrogen and oxygen. I am not sure I understand where they are coming from. Thanks again for everything

[Borek]

From the air - they are just dissolved. IIRC gas solubility changes with the addition of electrolytes.

[pizza1512]

So does that mean there is a way of measuring the rate of solubility of a substance (just to clarify I am not talking about the solubility of a substance at a certain temperature).