# Question #6615d

Jun 13, 2017

Here's my explanation.

#### Explanation:

The hydrogen carbonate ion, $\text{HCO"_3^"-}$, does not exist by itself.

It must be paired with a positive ion such as $\text{Na"^"+}$ or $\text{NH"_4^"+}$.

So, we can have compounds like ${\text{NaHCO}}_{3}$ and ${\text{NH"_4"HCO}}_{3}$, and they are all solids at room temperature.

However, in aqueous solution, the ions separate from each other, as in

$\text{NaHCO"_3"(s)" → "Na"^"+""(aq)" + "HCO"_3^"-""(aq)}$

I suppose you would say that in this case the hydrogen carbonate ion is in an "aqueous" state.