Thread: insight into the formation of Carbonic Acid please.

So the formula stands as the following CO2+H2O >>>> H2CO3


Can you please explain how the H2 and CO3 came about.

Originally Posted by chrisman10

So the formula stands as the following CO2+H2O >>>> H2CO3


Can you please explain how the H2 and CO3 came about.

Well think about it, you have 2 hydrogen atoms in H2O. (2 hydrogen atoms = H2)
You have 1 carbon catom in CO2 (one carbon arom = C)

You have 1 oxygen atom in H2O (one oxygen atom = C0
You have 2 oxygen aroms in CO2 (two oxygen atoms = C2)

The above three oxygen atoms = O3
Amount of carbon atoms is still 1, so we now have CO3
Amount of hydrogen aroms is still 2, so we now have H2CO3

I hope that makes sense?

I did try to find a diagram showing the whole reaction, but I couldn't find one, so...

In the reaction, the water molecule acts as a nucleophile, as the partially negative oxygen atom in the water molecule attacks the partially positive carbon atom. The result of this interaction is a bicarbonate ion and a free hydrogen ion.

The carbonic acid is formed when the hydrogen ion bonds to the bicarbonate ion.

Water would dissociate into H+ and OH- in small amounts.

H+ H-O: + O=C=O > H-O-C(=O)-O: <-H+

There's a nucleophilic attack by the hydroxide onto the C, which has a partial positive charge. One pair of electrons from one of the double bonds has to move onto the Oxygen, giving it a negative charge, which causes it to react with a free hydrogen.

Then you get H2CO3

Edit: which is exactly what Drowsy said, but in a bit more detail.