You know that antacid tablets which contain a basic substance are used to relieve
the discomfort caused by the acidity in stomach. Have you inquired into the reason
for it?
You have studied the fact that when acids react with bases, salts and water are
produced. Let's consider the reaction between hydrochloric acid and sodium
hydroxide again.
Let's investigate how water was formed as a product in the above reaction. The H+
ions released by the ionisation of the acid combine with the OH- ions given by the
ionisation of the base to form water molecules. it can be represented by a chemical
equation as follows.
In all acid - base reactions, the above common reaction occurs. This process is known as neutralisation.
Neutralisation is the combination of H+
ions released by an acid with OH-
ions
released by a base to form water molecules.
Hence, when an acid reatcs with a base their acidic properties as well as the basic
properties disappear.
Applications of the acid - base neutralisation reactions
• Milk of magnesia or such an antacid (a weak base) is used to neutralise the
acidity in the stomach.
• Basic substances such as ash and quicklime (calcium oxide) are added to soil to
reduce soil acidity.
• Bee sting is painful because of an acidic poisonous substance injected into the
skin. By applying a weak basic substance such as baking soda (NaHCO3
) or
calcium carbonate (CaCO3
) on the place of the sting, the pain is relieved.
• Wasp sting is basic. Application of a weak, dilute acid such as lime juice or
vinegar on the place of sting reduces the venomous nature as well as the pain.
