Acids

Acids:

Acid is a substance which produces hydrogen ions, H⁺, when it is dissolved in water.

All acids contain hydrogen ions, but not all compounds that contain hydrogen are acids, e.g. NH₃. This is because NH₃ does not produce hydrogen ions in water. It is the hydrogen ions produced that are responsible for the properties of acids.

Properties of Acids:

1. Acids have a sour taste.
2. They have a pH below 7.
3. They are generally corrosive in nature. The lower the pH, the more corrosive they are.
4. They turn blue litmus paper red.
5. They dissolve in water to form solutions that conduct electricity.
6. Acids react with reactive metals to form hydrogen and a salt.     metal + acid -> salt + hydrogen
7. Acids react with carbonates to form a salt, carbon dioxide and water.    carbonate + acid -> salt + carbon dioxide + water
8. Acids react with metal oxides and hydroxides to form a salt and water.    metal oxide + acid -> salt + hydrogen

Acids only show the properties of acids when they are dissolved in water. This is because acids dissociate in water to produce the hydrogen ions which are responsible for the acidic properties.