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Neutralisation – Definition, Neutralization Reaction, Applications

Sep 1, 2022


You must have sometimes faced acidity or burning sensation problems in your stomach. You go through stomach aches or burning sensation problems when eating something spicy or overeating due to tasty food. It is suggested to eat antacids to cure the acidity at that time.

But do you know how antacids help you in curing your acidity problems? What chemical reaction takes place between them? What is neutralization? What are its other applications?


Let’s dive into this article to know more about neutralization reactions.

Definition of Neutralization 

When two contrasting properties counterbalance each other, that is called neutralization. In chemistry, some materials or substances are basic, while some other materials or substances are acidic. These are opposite properties. When an acidic substance meets a basic substance, they change into something neither acidic nor basic (neutral). The reaction is called neutralization.


To answer the question of what is neutralisation, it is a chemical reaction or a process of reaction between acids and bases to form a neutral substance.

Usually, the neutralization reaction is represented as


Acid + Base → Salt (neutral) + Water

Types of Neutralization Reactions

Neutralisation of acids and bases takes place in four ways. These are


1. Strong acid and strong base:

When a strong acid (say HCl) reacts with a strong base (say HaOH), it gives salt (i.e., a neutral product) and water as the products. Such neutralization reactions are termed strong acid-strong base neutralization reactions.

HCl + NaOH → NaCl + H₂O


2. Weak acid and weak base:

When a weak base reacts with a weak acid, it gives weak salt its neutral product and water. Such reactions are known as weak acid-weak base neutralization reactions.



These reactions remain in equilibrium due to the partial decomposition of weak acid and base ions.

3. Strong acid and weak base:

Strong acids react with weak bases and produce salt and water in such reactions. These reactions are known as strong acid-weak base neutralization reactions. Due to strong acids, the salt formed is quite acidic. For instance,


H₂SO₄ + 2NH₄OH → (NH₄)₂SO₄ + 2H₂O

4. Weak acid and strong base:

A weak acid combines with a strong base to produce a basic salt and water in a weak acid-strong base neutralization reaction. Water exemplifies this reaction when CH₃COOH (acetic acid) combines with NaOH to create sodium acetate.


Neutralization Examples

  1. Reaction between sodium hydroxide and sulphuric acid

2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

  1. Reaction between non-metals and bases

2NaOH + CO₂ → Na₂CO₃ + H₂O

Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

  1. Reaction between metal oxides and acids

CuO + 2HCl → CuCl₂ + H₂O

  1. Some more neutralization examples are

H₂CO₃ + 2KOH → K₂CO₃ + 2H₂O

Fe(OH)₃ + 3HNO₃ → Fe(NO₃)₃ + 3H₂O

Ba(OH)₂ + 2HNO₃ → Ba(NO₃)₂ + 2H₂O

3Ca(OH)₂ + 2H₃PO₄ → Ca(PO₄)₂ + 6H₂O

Mechanism of Neutralisation of Acids and Bases

When an acid is mixed with a base, both solutions counterpoise the effect of each other. If both solutions are mixed in suitable amounts, the nature of both solutions is destroyed. The resulting solution is neither acidic nor basic but a neutral one.

The mechanism of such a reaction is understood by taking the example of an acid-base reaction. During the neutralization reaction, the acid’s H⁺ (or hydrogen ion or proton) is cancelled out or neutralized by the OH⁻ ion (hydroxyl ion or anion) present in the base. Complete neutralization is said to occur when all the H⁺ ions from acid are neutralized by the same amount of OH⁻ ions of the base.

The neutralization reaction of a strong base and strong acid has a pH equal to 7. The cancellation of a strong acid and weak base will have a pH of less than 7. Contrarily, the pH of a strong base and weak acid chemical reaction will be greater than 7.

Uses of Neutralisation Reactions

Some uses of neutralization reaction which you have seen are as follow:

  • In treating wasp stings, a wasp sting’s venom is basic. When vinegar is applied to it, the sting gets neutralized due to the vinegar’s acidic character.
  • In the treatment of soils: If the nature of the soil is too acidic or basic, the plants do not grow properly. Neutralized acids or bases are added according to the requirement of the soil to make the soil fertile or proper for the plants’ growth.
  • To treat gastric patients or acidity: There is a strong acid present in the stomach that helps in digestion. If the amount of this acid increases, you start to feel a burning sensation or acidity in your stomach. Antacids or some medicines containing bases are given to such patients. As a result, the excess acid in the stomach gets neutralized.
  • Bases like baking soda, etc., are applied to the bee stings in the treatment of bee stings. It neutralizes the formic acid released by a bee sting in your body.
  • To prevent latex coagulation: There are some bacteria in the latex that produce lactic acid. As a result, coagulation takes place. Ammonia solution (i.e., base) is used to prevent latex coagulation.
  • In the treatment of cavities: Most food items you intake are acidic. Toothpaste is used during brushing to neutralize these acids. It prevents the enamel from depositing on the teeth.

Applications of Neutralization 

Several neutralization examples occur in your daily life. You must have seen any of them but never recognized them.

  • Neutralisation is used in wastewater treatment to reduce effluent-created damage. If this wastewater, carrying hazardous acids, is discharged into the water bodies, in that case, it kills the fish and other water-living beings. Therefore, it is necessary to treat wastewater before discharging.
  • Neutralisation aids in conditioning hairs and the scales to close up. The shampoo you use contains alkaline substances. It causes the scales on hair. As a result, your hair becomes unmanageable. Hair conditioners are applied to prevent this situation.
  • Preparing table salt or sodium chloride is also an application of neutralization. It is formed by the reaction of strong acid, i.e., hydrochloric acid, and strong base, i.e., sodium hydroxide.
  • The burning of fossil fuels releases large quantities of sulphur dioxide gas. When mixed with water in clouds, it forms acid rain. Similarly, limestone and lime neutralize the gases released into the atmosphere.
  • Acids are used to neutralize base spills, and bases are used to neutralize acid spills.
  • During the production of drugs, the titration technique is used repeatedly to control the quality of drugs.
  • Preservation of food utilises acid. In vinegar, acetic acid (ethanoic acid, CH₃COOH) kills bacteria and inhibits bacterial growth. It is achieved indirectly by inhibiting important biological processes and enzymes in bacterial cells.


To conclude, you are now well-versed with the neutralisation reaction. An acid and a base react with each other in these reactions, forming a neutral (or salt) and water as the products. They are also termed acid-base neutralisation reactions.

Generally, the neutralisation of acids and bases liberates heat. Therefore, they are exothermic reactions. Such a reaction is employed in our everyday life also.

Frequently Asked Questions

1. What is neutralization in chemistry?

A chemical reaction known as neutralization occurs when an acid and a base quantitatively react with one another. Alternate spellings include Neutralization. The pH of the neutralized solution is determined by the acidity of the reactant.

2. What is a real-life example of neutralization?

Real-life examples: When a person has acid reflux, he is advised to take antacid tablets. This is due to the basic nature of antacids, which neutralizes excess acid in the stomach. When an ant bites us, we treat it with a calamine solution.

3. How do you neutralize acids?

A weak base is used to neutralize acids. Bases have an astringent or bitter taste and a pH greater than 7. Sodium hydroxide, potassium hydroxide, and ammonium hydroxide are examples of common bases. A weak acid is used to neutralize bases.

4. What happens to acid during neutralization?

A neutralization reaction occurs when an acid and a base react to form water and salt through the combination of H+ ions and OH- ions. The pH of neutralization of a strong acid and a strong base is 7.



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