Question

In the reaction between `HCl` and `Na_2CO_3`, what gas is formed?

Answer 1

Carbon dioxide.

Explanation:

Sodium carbonate, `"Na"_2"CO"_3`, will react with hydrochloric acid, `"HCl"`, to produce sodium chloride, a

soluble ionic compound that exists as ions in solution, and carbonic acid, `"H"_2"CO"_3`.

Now, carbonic acid molecules are highly unstable in aqueous solution, so they actually decompose to form carbon dioxide, `"CO"_2`, which bubbles out of solution, and water.

You can thus say that you have

`"Na"_2"CO"_text(3(aq]) + 2"HCl"_text((aq]) -> 2"NaCl"_text((aq]) + "H"_2"CO"_text(3(aq])`

But since

`"H"_2"CO"_text(3(aq]) rightleftharpoons "H"_2"O"_text((l]) + "CO"_text(2(g]) uarr`

Your overall reaction will look like this

`"Na"_2"CO"_text(3(aq]) + 2"HCl"_text((aq]) -> 2"NaCl"_text((aq]) +"H"_2"O"_text((l]) + "CO"_text(2(g]) uarr`

The net ionic equation, for which spectator ions are omitted, will look like this

`"CO"_text(3(aq])^(2-) + 2"H"_text((aq])^(+) -> "H"_2"O"_text((l]) + "CO"_text(2(g]) uarr`