• Acids
  • Examples of acids


Substances that ionize (break off) in an aqueous solution to produce hydrogen (H+) ions are known as Acids, and the substances that ionize in an aqueous solution to produce hydroxide (OH-) ions are known as Bases.


Salts in chemistry are substances produced by the neutralization reaction of an acid with a base. A salt is a compound composed of two ions, a positively charged ion and a negatively charged ion. The attraction between the two ions forms solid ionic bonds, giving salts a hard and brittle crystalline structure.



The process where acids and bases neutralise each other to form salt and water is known as neutralisation.



  • Acid is a compound which yields hydrogen ions (H+) when dissolved in water.
    HCl + H
    2O → H++ Cl
  • Acid is sour to taste and corrosive in nature. The pH of acids is less than 7.
  • All acids react with the metal to release hydrogen gas. For example, zinc metal reacts with hydrochloric acid to form zinc chloride and hydrogen gas.
    Zn + 2HCl ZnCl2 + H2
  • When acids react with limestone (CaCO3), it produces carbon dioxide. For example, HCl reacts with limestone to produce carbonic acid and calcium chloride.
  • Acids are classified into organic and inorganic acids. The best example of organic acid is acetic acid (CH3COOH), and inorganic acids are produced from minerals; for example, sulphuric acid (H2SO4) and hydrochloric acid. Etc.
  • Acid usually converts blue litmus paper to red litmus paper.

  • Acids tend to corrode metal surfaces quickly.
  • Some Acids are highly corrosive.
  • In an Acidic solution, Methyl orange gives Red colour.
  • Acids turn the pink colour of Phenolphthalein to colourless.

Examples of Acids:- Lemons, oranges, vinegar, sulphuric acid, and hydrochloric acid.

Uses of Acids:- Benzoic acid (salt used to preserve food),

Carbonic acid - Used to make carbonated drinks. 

Ethanoic acid - Used to clean metals before electroplating/processing leather/household cleaning/ maintenance of swimming pools.

Sulphuric acid - To make fertilizers, polymers, and detergent

Strong acids: These acids get completely (100%) ionized in the aqueous solutions. Thus, at equilibrium, the concentration of acid molecules becomes significantly less, and the concentration of hydrogen ions reaches the maximum; for example, HCL, HNO3, HClO4

Weak acids: These acids are only partially ionized in solution at an equilibrium state. At the equilibrium state, molecules of acid are present in a considerable amount, and the concentration of hydrogen ions is less, for example, HF, CH3COOH.




  • Bases are compounds that yield hydroxide ions (OH−) when dissolved in water.
  • Bases are bitter in taste and corrosive in nature. They usually feel slippery and very soapy.
  • Bases are good conductor of electricity and usually shows a pH value of more than 7.
  • Bases react with oils and grease to form molecules of soap.
  • Bases convert red litmus paper to blue litmus paper.

  • In the Basic solution, Methyl orange gives Yellow colour
  • Phenolphthalein solution turns pink in the presence of a base

Examples of BASES:- Soap, toothpaste, bleach, cleaning agents, lime water, ammonia water, and sodium hydroxide.

Uses of BASES:-

Ammonia - Used in producing fertilisers that manufacture nitric acid to prevent clotting in natural and synthetic latex.

Aluminium hydroxide - Often used to make gastric medicine-antacid.,

Calcium hydroxide - Used to make cement and lime water, help with the application of sewage treatment and neutralise soil's acidity.

Strong bases: These are the bases which are completely ionized in water to produce hydroxide ions, e.g., sodium hydroxide.

NaOH(s) ⇌ Na+(aq) + OH(aq)

Weak bases: These are the bases which are partially ionized, and the equilibrium lies mainly towards the reactants side, e.g., ammonia in water.

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH(aq)




  • Salts are ionic in nature due to the presence of ions.
  • They are brittle, hard and crystalline solids.
  • Salt is white, odourless, and it has a salty taste.
  • All potassium (K), ammonium (NH4+) and sodium (Na) salts are soluble in water (H2O).
  • Sodium Chloride(NaCl), generally known as ‘Common salt’ or ‘Table salt’ is used in our day-to-day life.

Examples of Salts:-:- Copper Sulfate, Sodium Bisulfate, Calcium Chloride, Potassium Dichromate, Sodium Chloride

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Video Tutorials | Acids, Bases and Salts Introduction

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