Dhristi JEE 2022-24

What is Sulfuric Acid?

Sulfuric acid (H2SO4) contains elements sulfur, oxygen, and hydrogen. It is known as oil of vitriol or hydrogen sulphate. It is one of the most important chemicals from the commercial point of view. The reaction of water and sulfur trioxide results as product sulfuric acid. The sulfur trioxide is made by the chemical combination of sulfur dioxide and oxygen or chamber process. In nature, pure sulfuric acid does not exist due to its strong affinity to water. It is supplied at different concentrations for different applications.        


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Sulfuric acid formula 

The sulfuric acid molecular formula is H2SO4. It has one atom of sulfur, four oxygen atoms attached to the sulfur atom and two hydrogen atoms attached with two oxygen atoms. Two oxygens are attached to the sulfur by a double bond, and two hydroxyl groups are attached by a single bond. It is an oxoacid of sulfur. According to the VSEPR Theory, The structure is arranged in such a way that there is minimum repulsion between lone pairs and bond pairs. Its molecular weight is 98.079 g/mol. Sulfuric acid density is 1.83g/cm3. Its boiling point is 337oC , and its melting point is 10oC.

Sulfuric acid uses

Some of the sulfuric acid uses are given below.

  • Fertilisers: Sulfuric acid is used in huge amounts to make phosphoric acid, which is used for the preparation of phosphate fertilisers.

  • Pharmaceuticals: It is used as a solvent for the chemical synthesis of a variety of chemical substances, including active pharmaceutical ingredients. One type of active pharmaceutical ingredient manufactured by using sulphuric acid are the alkylating agents which are commonly used in chemotherapy (treatment of cancer).

  • Gasoline: Sulfuric acid is also present in samples of gas for CEMS.

  • Automobile batteries: It is used in the manufacturing of Lead-Acid type batteries. In the automotive industry for cars and trucks, sealed-unit lead-acid type batteries are used.

  • Paper bleaching: In the pulp and paper industry, sulfuric acid is used for the on-site generation of chlorine dioxide, the key bleaching agent for the environmentally-friendly ECF chemical pulping process.

  • Water treatment: In wastewater treatment, an acid or a base is added, depending on the pH level of the water being treated. Either sulfuric acid or a base chemical is used to bring the pH level of wastewater back to normal, and this process is known as neutralisation.

  • Cellulose fibres: Sulfuric acid is also used for the making of cellulose fibres such as rayon fibre.

  • Steel manufacturing: Nowadays, petroleum refining is used effectively to wash impurities out of gasoline and other refinery products. It is used in processing metals, for example: in pickling or cleaning of iron and steel before plating with tin or zinc.

  • Colouring agents: It is used in the preparation of dyes, drugs, and disinfectants as colouring agents. 

  • Regeneration of ion exchange resins: It is generally used to regenerate strong acid cation resins. It is used in order to control the precipitation of calcium sulfate. Regeneration with reduced concentrations of sulfuric acid at selected flow rates is necessary.

Electrolysis of concentrated sulfuric acid

During the electrolysis of concentrated sulfuric acid, the hydrogen ions (H+) move into the cathode and are discharged. Two reactions are given below that occur at the anode and cathode.

Anode: { 2H2SO4 → H2S2O8 + 2H+ 2e-

          2H2O→ O2 + 4H+ + 4e-   }

Cathode: { 2H2O → H2 + 2OH- - 2e- } x 3

The final equation is as follows.

Equation: { 2H2SO4 + 8H2O → H2S2O8 + O2 + 3H2 +6H+ + 6OH- }

Manufacture of sulfuric acid

For the production or manufacture of sulfuric acid, the material required is dry and clean sulfur dioxide gas. This is formed through the oxidation of elemental sulfur. Sulfur dioxide (SO2) in the presence of a vanadium catalyst is oxidised to sulfur trioxide (SO3) in the contact process at a high temperature. In concentrated sulfuric acid, sulfur trioxide is dissolved and forms oleum (fuming sulfuric acid).

From the sulfur element, it is manufactured in a three-stage process. These steps are as follows.

S + O2 →  SO2

2SO2 +O2 → 2SO3

SO3 + H2O → H2SO4

Phenol sulfuric acid method

The phenol sulfuric acid method is one of the most reliable methods of carbohydrate analysis. The phenol-sulfuric acid method is used to find carbohydrates in a sample.  It is a simple and rapid colorimetric method. The concentrated sulfuric acid breaks down  In the phenol sulfuric acid method into any polysaccharides, oligosaccharides, and disaccharides into monosaccharides.

Material: Phenol 5%, sulphuric acid 96% reagent grade and Standard Glucose.


  1. Take a boiling tube and weigh 100mg of the sample in it.

  2. Keep the boiling tube in water for around three hours with 5mL of 2.5 N-HCl in order to hydrolyse it, then cool it to room temperature.

  3. Na₂CO₃ is used to neutralise until the effervescence ceases.

  4. Now in the next step, make up the volume to 100mL and centrifuge into different test tubes, pipette out 0.2, 0.4, 0.6, 0.8 and 1mL of the working standard.

  5. 0.1 and 0.2mL should be pipette out in two separate test tubes and make up the volume to 1mL with water in each tube.

  6. Set a blank with 1mL of water.

  7. 1mL of phenol solution will be added to each tube.

  8. 5mL of 96% sulfuric acid will be added to each tube and shaken well.

  9. After a duration of 10min, shake the content in the tubes and place in a water bath at a temperature between 25oC - 30°C for 20min.

  10. Read the colour at 490 nm.

  11. With the help of using the standard graph, calculate the amount of total carbohydrate present in the sample solution.

Do you know?

  • One of the most important industrial chemicals in the world is Sulfuric Acid. It is also widely used in batteries of cars. The main producer of sulfuric acid is the United States of America and China.

  • Oil of Vitriol is the name of sulfuric acid, which was used in history. In the medieval period, European Alchemists called it by this name because it was prepared in an iron retort by roasting “green vitriol”. 


Sulfuric acid is called the universal chemical and king of chemicals because it offers a wide range of applications. We get all the information, which is important such as sulfuric acid formula, its uses, electrolysis as well as manufacturing methods etc. 

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FAQs (Frequently Asked Questions)

1. What is the World’s Strongest Acid?

Carborane superacids are considered the strongest solar acid across the world because fluoroantimonic acid is a mixture of hydrofluoric acid and pentafluoride antimony in reality.

2. What is Sulfuric Acid Used For?

The major application of sulfuric acid is in fertilizer processing, for example, ammonium sulfate and lime superphosphate. 

Commonly, it can be used in chemical processing, for example, in the manufacturing of different compounds such as nitric acid, hydrochloric acid, synthetic detergents, sulfate salts, pigments & dyes, medicines, and explosives.

3. Is it Possible to Neutralize Sulfuric Acid With Water?

When we have some amount of conc. sulphuric acid, we should pour it into the solution of sodium hydroxide. Then, the water will dilute and carry off some amount of heat that either the bicarbonate or sodium carbonate produces when it neutralizes the acid.

4. How to Neutralize Sulfuric Acid?

Pour the baking soda into an acid spill. This will neutralize the light acids like vinegar, or even toxic, and strong acids such as sulphuric and muriatic acids. Douse with baking soda (such as NaHCO3, sodium bicarbonate) in the total contaminated region to neutralize the acid.

5. Is Sulfuric Acid Molecular or Ionic?

Water forms a compromise between H3O+, H2O and -OH, which does not make anything ionic. Sulfuric acid is given as a compound with covalent bonds since the total bonds are covalent. The fact is, it ionizes readily insignificant to debate.

6. What is dilute sulphuric acid?

An acid is called diluted when water concentration mixed in the acid is greater than the concentration of the acid. Hence, when the concentration of sulfuric acid is lower than the water concentration in the mixture, the solution is called dilute sulfuric acid. Dilute sulfuric acid is used in electrolysis because it is highly ionised. 

Much of the heat emitted by sulfuric acid while diluting comes from the hydration of hydrogen ions. It reacts with many metals (for instance, Zn), releases hydrogen gas (H2) and forms the sulfate of the metal. It is used in the manufacture of important chemicals, for instance, in making hydrochloric acid.

7. What is Sulfuric acid used for?

Sulfuric acid is a useful chemical that is used for a variety of applications such as the manufacture of detergents, fertilisers, inorganic salts, drugs, pigments, dyes, explosives, and acids, as well as in the refining of petroleum and metallurgical processes. It is used in metallurgical processes for the purification of metals by electrolysis, where sulphuric acid is commonly used in the bath. 

It is used in preparing paints and pigments. Sulfur amino acids are very significant among amino acids due to their numerous roles. They are precursors of different components, for example, H2S, taurine, sulfates, glutathione and work on oxidative status and various signalling pathways.