Neutralization is a chemical reaction in which an acid reacts with a base or an alkali to form salt and water.
Acids, alkalis, and bases
An acid is a substance that dissolves in water to form a solution with a pH below 7.
A base is any substance that only reacts with an acid to form salt and water.
Examples include metal oxides and metal hydroxides.
The process in which this happens is called a neutralization reaction.
Some bases are soluble in water. These are called alkalis, which have a pH of 7 and above.
Pure water is neutral, with a pH of 7.
Neutralization reactions are exothermic, meaning that the reaction mixture is heated during the response.
Reactions with metal oxides
acid + metal oxide → salt + water
The salt made depends on the specific metal oxide and acid.
For example, copper chloride is made if copper oxide and hydrochloric acid are combined in a neutralization reaction.
Reactions with metal hydroxides
Some metal hydroxides dissolve in water, so they form alkaline solutions.
acid + metal hydroxide → salt + water
As with metal oxides, the salt depends on the metal hydroxide and the acid used.
How is neutralization used?
In the body, neutralization can stop the stomach from producing too much hydrochloric acid.
This can be done by ingesting antacid tablets which contain bases such as magnesium carbonate.
In nature, bee stings are acidic, and baking powder can neutralize the acid in the sting.
Farmers also use lime (calcium oxide) to counteract and neutralize acidic soil.