Question

What is `"carbonic acid"`?

Answer 1

Carbonic acid is a label of convenience.

Explanation:

You cannot buy a bottle of `H_2CO_3`, as you can buy bottles of `HX`, or `H_2SO_4`, or `H_3PO_4`, YOU CAN saturate a volume of water with `CO_2` to give what we would represent as `H_2O*CO_2`. (And note that `H_2O*CO_2-=H_2CO_3`.) The carbonated water that we drink for lunch is an example of water that is SUPERSATURATED with respect to carbon dioxide.

And this is an acidic oxide that could react with 1-2 equiv of base to give bicarbonate or carbonate salts.......

`H_2O*CO_2(aq) + NaOH(aq) rarr Na^(+)HCO_3^(-)(aq) + H_2O(l)`

`H_2O*CO_2(aq) + 2NaOH(aq) rarr Na_2^(+)CO_3^(2-)(aq) + 2H_2O(l)`

Answer 2

So if the reaction we want to write is the formation of `"H"_2"CO"_3` from `"H"_2"O"` and `"CO"_2`, then we can write the reaction as `"H"_2"O" + "CO"_2 -> "H"_2"CO"_3`.

Explanation:

A reaction is made up of reactants and products. The reactants are (usually) put on the left side of the equation, and the products are put on the right side of the equation. In this reaction, `"H"_2"O"` and `"CO"_2` are our reactants, and `"H"_2"CO"_3` are our products.