[ZekR]

This is very basic, but I want to make sure I correctly understand the bold sentence in this paragraph:

When an ionic carbonate, such as K₂CO₃, is treated with an acid, such as HCl, one of the products is carbon dioxide. Such reactions occur through the formation of a gas and water because both products remove reactant ions from solution:
2HCl(aq) + K₂CO₃(aq) 2KCl(aq) + [H₂CO₃(aq)]
[H₂CO₃(aq)] H₂O(l) + CO₂(g)
The product H₂CO₃ is shown in square brackets to indicate that it is very unstable. It decomposes immediately into water and carbon dioxide.

Are the reactant ions that are removed from solution by the products in the above example the H⁺ (or rather H₃O⁺) ions ("removed" by becoming H₂O product) and the CO₃^2- ion ("removed" by becoming CO₂ product)?

[Arkcon]

That's one way of looking at it.  It seems to be what this question is trying to make clear, with the italicized portion.  There's something more important 'tho.  That the question glosses over, that may be more significant:  Do you think that the reaction: 2HCl(aq) + K₂CO₃(aq) 2KCl(aq) + [H₂CO₃(aq)] could be an equilibrium?

[ZekR]

No, it could not be an equilibrium, since H₃CO₃ immediately breaks down into H₂O(l) and CO₂(g) (and CO₂(g) is a gas so it escapes).  And they would use double reaction arrows if it were an equilibrium, right?

What the text book in question (Silberberg) is talking about in this section is acid-base reactions and how the gas forming reaction in essence is an acid-base reaction.  Here is a bit more from the book that follows where I left off in the italicized portion of my original question:

Combining these two equations gives the overall equation:
2HCl(aq) + K₂CO₃(aq)  2KCl(aq) + H₂O(l) + CO₂(g)

When we show H₃O ions from the HCl as the actual species in solution and write the net ionic equation, Cl and K ions are eliminated. Note that each of the two H₃O ions transfers a proton to the carbonate ion:
2H₃O⁺(aq) + CO₃^2-  2H₂O(l) + [H₂CO₃(aq)]  3H₂O(l) + CO₂(g)

In essence, this is an acid-base reaction with carbonate ion accepting the protons and, thus, acting as the base. Several other polyatomic ions react similarly with an acid.

[Arkcon]

The gas evolution does drive the equilibrium far to the right.  And that's what the text seems to be trying to say.