Acid-Base Reactions
In an acid-base reaction, a proton(H+) is transferred between chemical species. Acid-base reactions are common in lakes, our body's blood, and even industrial production of fertilizers. H+ is just H without its one electron, which makes it just a proton.
So, what are an acid and a base? The Brønsted-Lowry definition of an acid is any species that donates a proton while the Bronsted-Lowry definition of a base is any species that accepts a proton.
HCl + H2O → H3O++Cl-
The following reaction above is a classic acid-base reaction. HCl (Hydrochloric acid) is an acid and it reacts with water to form the following products. Notice how water becomes the hydronium ion as it now has an extra H and a +1 charge. This is because the HCl dissociated and donated a proton to the water and what was left is the HCl without the H+, so just Cl-. This makes water the proton acceptor in this case, making it the base
HCl→ H+ + Cl-
A more simplified way to represent this reaction is above and it disregards water because the reaction anyways takes place in aqueous solution so placing water in the reaction is somewhat redundant.
This is a classic acid-base reaction and it can be visualized below.
As you can see, the green chloride ions were originally with the H+ ions but then the base took them and we are left with just chloride atoms.
An acid-base reaction where water is the acid is certainly possible. By the way, to be both a viable acid and base is called being amphoteric and water is an amphoteric substance.
NaOH → Na+ + OH-
The reaction above is an example of a strong base dissociating.
Acids and bases are classified by their strength. Strong acids dissociate fully so pretty much all of the hydrogen in a solution of strong base gets transferred into water. Similarly, strong bases dissociate to form hydroxide(OH-) ions. These concepts are explored in greater detail in this later section but the intuitive gist of an acid-base reactions and the transferring of protons is the idea here.