Free science tutorial on chemistry of acids and bases

Many of the substances we use are either acids or bases. These two are mutually interacting materials. Acids and bases are having many industrial applications. This article explains the chemistry of acids and bases.


Acids and bases, these two words are very common. Many of us will be using these words many times in our daily life. These two are interactive substances. They react with each other and form neutral substances called salts and water. The word acid is derived from a Latin word called 'acere'. The meaning of this word is sour.

Both acids and bases are having a wide range of industrial uses, and many of the items we use in our day-to-day life are either acids or bases. For example, we all use lemons in many foods. The scientific name of these lemons is Citrus limon. This will contain Citric acid. Similarly, milk will have lactic acid. Washing soda is nothing but sodium carbonate which is a base.


Different theories have been proposed to define an acid and a base. These are-
  1. Arrhenius Theory: The Swedish scientist Arrhenius defined acids and bases. As per his theory, an acid is a substance that increases the concentration of H+ ions in water when the same is dissolved in water. A base is a substance that increases the concentration of OH– ions in water when the same is dissolved in it.

    Acids are substances that can donate a proton and bases are substances that can accept the proton from an acid. Proton is nothing but a hydrogen ion. A hydrogen atom contains one proton and one electron. By losing an electron it will become an H+ ion which is nothing but a proton. A base will accept the H+ ion and in this bargain, salt and water will be formed. For example, Hydrochloric acid gives H+ ion to sodium hydroxide. In this reaction, water and sodium chloride will be formed. Sodium chloride is nothing but the common salt we use in our food as an ingredient.

  2. Bronsted Lowry Theory of Acids and Bases: As per this theory all proton donors are acids. Proton acceptors are bases. But there are acids that will not have any H+ ions and there are some bases that will not have OH- ions. Both the above theories are not able to explain this concept.

  3. Lewis Concept of Acids and Bases: In this theory, there is no concept of H+ ions and OH- ions.
    An acid is a substance that will have a vacant orbital and accept electron pairs. A base is a substance which is having the ability to donate an electron pair.

    Thus, an acid will accept electron pair from a base forming a coordinate covalent bond. A coordinate covalent bond is a bond that will be formed by sharing of a pair of electrons. The paired share will be from the same atom whereas in a covalent bond each atom will contribute one electron for sharing and the two electrons will become common for both substances.

Properties of acids:

The properties of acids are listed below
  1. Acids are sour.

  2. They convert blue litmus paper to red. When litmus paper is dipped in acid solution in water the colour of the litmus paper will change from blue to red.

  3. Their pH value will be always less than 7. pH is a measure of hydrogen ion concentration in the acid solution.

  4. They react with bases to form salt and water.

  5. Acids are good conductors of electricity.

  6. Acids react with metals to form hydrogen and salt. For example, magnesium metal reacts with hydrochloric acid to form magnesium chloride and hydrogen.

  7. Acids react with carbonates and form carbon dioxide, water, and salt.

  8. Acids react with hydroxides to form salt and water.

  9. Acids react only when they are in the water. In presence of water, only acids dissociate into hydrogen ions and these ions only are responsible for acidic properties.

  10. An acid will have a conjugate base. An acid after losing H+ will form its conjugate base.

The properties of bases are-
  1. Generally, bases are bitter.

  2. They convert red litmus to blue.

  3. The pH value of these substances will be above 7 and will be less than 14.

  4. They react with acids to form salt and water.

  5. Bases will release OH ions when dissolved in water.

  6. The aqueous solutions of bases are good conductors of electricity

  7. All bases are not soluble in water. Bases that are soluble in water are known as alkalis. Metal oxides and hydroxides are also bases but they are not soluble in water.

  8. A base will have a conjugate acid. A base after losing OH- ion will form its conjugate acid.


Many of the cleaning agents will contain acids and many detergents will contain bases. Many chemical reactions will take place only in acidic media or basic media. In the absence of these two materials, many developments in chemistry might not have taken place. Thus they play a very important role in human life.

Frequently Asked Questions

What is the qualitative test for acids and bases?
The litmus test is the best test. an acid will convert blue litmus paper to red. A base will convert red litmus paper to blue


Author: Umesh05 Sep 2022 Member Level: Diamond   Points : 3

This is an interesting article explaining acids and bases and their properties in a precise and compact manner and would be useful for the students who are revising their syllabus or course before the exams.

Acids and bases are used in the industry in a big way and we are also familiar with some of them which we use in our houses for cleaning. Water is also a good solvent and cleaning liquid but when it comes to sparkling cleaning, acids are required as they have a capability of removing the stubborn dirt spots and other stains from the tiles, metals and other such surfaces. Acids or bases can harm our skin by simply burning it so it is imperative that we should use gloves while using these liquids for any cleaning work in our houses. As acids and bases are reactive materials we have to be safety conscious before using them for any purpose especially when mixing them with other materials in a lab or industrial unit or even in the households.

Author: Sheo Shankar Jha05 Sep 2022 Member Level: Diamond   Points : 4

The author has tried his best to provide the students and other interested members with the different mechanisms of acid and alkalies, their inherent properties and other characteristics. Though we are aware that strong acids such as concentrated sulphuric acid, nitric acid and HCL are used extensively in the different industries so as to get the end products of our requirements but weak acids find its usage in our domestic use such as Lemon containing Citric Acid have the miracle properties for our body system such as removal of toxins from our body system, taking care of indigestion, regulating our blood pressure etc apart from its beneficial effects on its application for hair cleaning purposes if used with other additives. Similarly weak acetic acid also known as vinegar is frequently used with salads and also for culinary purposes.
Thus we can see that both weak acid and bases have different applicability in our domestic usages. They can offer us multiple benefits such as weak solution of alkali can be used for cleaning clothes and is also used for making soaps whereas weak oxalic acid, weak acetic acid and citric acids have their abundant usages in our households.
To sum up both acids and bases are the indispensable products and without the proper ideas of their usages, we can be deprived of proper applications of these items.

Author: S.Pattavarayan13 Jan 2023 Member Level: Gold   Points : 3

Acids and bases are important concepts in chemistry. An acid is a substance that donates hydrogen ions (H+) when dissolved in water, while a base is a substance that accepts hydrogen ions when dissolved in water. The concentration of hydrogen ions in a solution is measured using the pH scale, which ranges from 0 to 14. A pH of 7 is neutral, a pH less than 7 is acidic, and a pH greater than 7 is basic. Some common examples of acids include hydrochloric acid (HCl) and sulfuric acid (H2SO4), while some examples of bases include sodium hydroxide (NaOH) and ammonia (NH3). The chemical reactions of acids and bases can be described using the Bronsted-Lowry theory or the Lewis theory.

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