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Chemical substances that are corrosive in nature are classified into two categories – Acids and Bases.  Bases are also known as Alkali or neutral. This depends on its varied characteristics and pH scale. The pH scale is used to measure the acidity or alkalinity of a substance. 

Acids have a pH value between zero to seven, whereas Bases have a higher pH value between seven to fourteen.

Due to the different properties and uses, it is essential to understand the difference between acids and bases.

Acids and Bases Around Us

Acids and Bases play a crucial role in the environment surrounding us and in our day-to-day lives. The everyday things that we use or even the food we eat have acid or base. For example, lemon, vinegar, soaps and detergents are examples of Acids and Bases. 

While acid is known as a Proton donor, base is known as a Proton acceptor.

Acids are also found in the human body; these acids are beneficial for the human body. These are two types – organic acid and inorganic acid. Organic acid has carbon content, while inorganic acid does not have carbon content. 

Below are the differences listed between Acid and Base for a better understanding:

Parameters of ComparisonAcidBase
DefinitionIt is a substance with a pH value of less than seven when present in an aqueous solution. They donate hydrogen ions (H+). Hydrogen ion just has proton; it does not have an electron.It is a substance with a pH value greater than seven when present in an aqueous solution. They release hydroxide ions (OH-). A base, when added to water, is known as an Alkaline solution.
Arrhenius TheoryThis theory suggests that the concentration of Hydrogen Ions increase when it is dissolved in water (H2O)This theory suggests a concentration of hydroxide ions (OH-) increases when dissolved in water.
Brønsted-Lowry TheoryAcidic substances donate protonsThese substances accept protons
Lewis TheoryAcids are ions that accept a pair of electrons, also known as Electrophile. They contain vacant orbitals hence, termed Lewis Acid.Bases are ions that donate a pair of electrons, also knowns as Nucleophile. They contain single pair of electrons, hence, termed as Lewis Base.
Chemical FormulaThe chemical formula of all acids begins with H and will have at least one H in them—for example, HCl (Hydrochloric acid), H3BO3 (Boric Acid). There are exceptions, too, like CH3COOH (Acetic Acid).The chemical formula of bases ends with OH. For example, NaOH (Sodium Hydroxide), KOH (Potassium Hydroxide), NH4OH (Ammonium Hydroxide).
ClassificationClassified as:
Strong Acids: Hydrochloric Acid (HCL), Sulphuric Acid (H2SO4), Nitric Acid (HNO3)
 Strong Lewis Acids: Anhydrous Aluminium Chloride (AlCl3)
Concentrated Weak Acids: Acetic Acid (CH3COOH), Formic Acid: (CH2O2)
 Specific reactive Lewis Acid Zinc Chloride (ZnCl2)
Classified as: –
Caustics and Alkalis: Potassium Hydroxide (KOH), Sodium Hydroxide (NaOH)
 Concentrated Weak Bases: Ammonia (NH3)
Super Bases that very strong bases: Sodium Amide (NaNH2), Metal Amides, Alkoxides
StrengthDepends on the concentration of Hydronium IonsDepends on the concentration of Hydroxide Ions
IonisationOn ionisation, acids form Hydronium. For example, in H2O, compounds break to form hydrogen ion (H+)On ionisation, bases form Hydroxyl Ions
Phenolphthalein IndicatorAcid remains colourless when it is dissolvedBases turn pink when it is dissolved
Litmus Paper TestTurns a blue litmus paper into red colourTurns a red litmus paper into blue colour
DissociationWhen acids are mixed in water, they dissociate to release hydrogen ions (H+)When bases are mixed in water, they dissociate to release hydrogen ions (OH-)
Physical CharacteristicsSticky in natureSour in taste. Generally good conductor of electricity (they are electrolytes)Changes the colour of blue litmus paper to redThey react with metals like iron, aluminium, zinc or magnesium to release hydrogen. Have a burning sensationWater and Salts are produced when an acid reacts with base (alkalis)Feel slippery in nature when it is touchedBases are bitter in taste. Do not taste themReacts with acids to neutralise its propertiesGood conductor of electricity when a molten base solution or aqueous base solution is dissociated into ionsChanges the colour of red litmus paper to blue 

Different usage of Acids and Bases and their relatable examples: 


  • HCl (Hydrochloric Acid)- It is metal dissolvent. HCl helps in dissolving metals like Gold and Platinum
  • Sulphuric Acid (H2SO4) and Nitric Acid (HNO3) are commonly used in fertilisers, paints and explosives.
  • Acids are found in household cleaning liquids; however, the concentration of the acids will differ.
  • Batteries used in the cars and torchlights use Sulphuric Acid (H2SO4)
  • Sulphuric Acid (H2SO4) is also used in the mining industry for minerals processing
  • Acids are used to remove rust and corrosive surface from the metals
  • To produce salts, acids are used as neutralising agents in the chemical industry. For example, the fertiliser Ammonium Nitrate is produced by reacting HNO3 (Nitric Acid) and NH3 (Ammonia) together.


  • NaOH (Sodium Hydroxide) is used to manufacture detergents, soaps, paper, synthetic rayon fibre.
  • NAHCO3 (Sodium Bicarbonate) is used in making toothpaste, baking soda and in fire extinguishers too
  • Ca(OH)2 (Calcium Hydroxide) It is also known as slaked lime. It is immensely used for different purposes. It is used in the manufacturing of bleaching powder. Farmers use slaked lime to neutralise the harmful effects of acid rain on the farmland. 

It is also used in fungicides, whitewash mixtures in dentistry to neutralise the acid in the water supply, used as a dressing material for burns due to acids.

  • NH4OH (Ammonium Hydroxide) is used to cleaning agents to remove different stains from clothes
  • Alkaline batteries use Alkalis bases, like Potassium Hydroxide (KOH). Additionally, they are used in removing soil acidity and in deodorants.
  • Mg(OH)2, Magnesium Hydroxide is used anti-acid medicines that help neutralise the gastric acids in the human body.


To conclude, Acids and bases are a crucial part of different experiments and research in the field of science. They help in forming chemical and covalent bonds. 

Besides experiments, they are found abundant in everyday life, within the body, in food, environment, chemicals, pharmaceuticals and for many other usages. 

Thus, we understand the difference between Acid & Base. These need to be handled with a lot of caution to avoid any impact or damage to the human body. Hence it is imperative to understand the properties and characteristics of acids and bases before performing any experiment.