I am asking this because I know that acids are normally aqueous but according to the solubility rules, all carbonates are insoluble.

  • 2
    $\begingroup$ Have you looked at general references, such as the Wikipedia page for carbonic acid, before asking here? $\endgroup$
    – F'x
    Commented Oct 21, 2013 at 9:08
  • 7
    $\begingroup$ Also, all carbonates are not insoluble - the alkali metal carbonates, like [sodium carbonate](sodium carbonate) are soluble. $\endgroup$
    – Ben Norris
    Commented Oct 21, 2013 at 11:09
  • $\begingroup$ Please note that Arrhenius' definition of acidity is not the only one. $\endgroup$ Commented Jan 22, 2014 at 6:44

2 Answers 2


Yes, it is soluble.

For example, the oceans are constantly getting $\ce{CO2}$ from the atmosphere that gets converted into carbonic acid and thus decreasing pH on a global scale. Or the soft drinks we drink contain carbonic acid in them in dissolved form only due to mixing of $\ce{CO2}$ gas.

Also, not all carbonates are insoluble as Ben Norris has commented.

Hard and fast 'rules' in chemistry tend to be rare. Consider them guidelines.

  • $\begingroup$ The oceans are only "constantly getting CO2" when we've filled the atmosphere with gaseous CO2 to disrupt the equilibrium. Prior to the last century, the oceans were mostly in a nice dynamic equilibrium with atmospheric CO2 (save a few nasty turns here and there) $\endgroup$
    – ericksonla
    Commented Feb 22, 2016 at 14:27

Yes, it is soluble.

The fizzy part of your soda does not form a layer at the bottom of the bottle. (Personally, I find the empirical solutions best for chemistry)

The carbonate rule only applies to alkali metal carbonates.

Also, as a general rule, anything with the word "acid" is probably soluble in water. Seeing as acids are sometimes defined as yielding $\ce{H+}$ ions when dissolved.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.