What are acids and bases?

There are multiple definitions for these concepts. One of the most widely used is the Arrhenius acid-base definition, coined by Swedish scientist Svante Arrhenius. Accordingly, when dissolving in water, substances that give hydrogen ions (H3O+) to the solution are defined as acids, and substances that give hydroxyl (OH-) ions are defined as bases.

When the hydrogen atom with a proton and an electron gives an electron, the positively charged hydrogen ion is formed.

The degree of acidity is measured by the pH value. Solutions with a pH value below 7 are acidic, solutions above 7 are basic. Solutions with a pH value of 7 are neutral.