[Chemistry Class Notes] on Sulphuric Acid Pdf for Exam

Acids are those substances that release hydrogen or hydronium ions when dissolved in their solutions. Acids can also be defined as those substances which donate a proton. Sulphuric Acid is a strong mineral acid, which is represented by the chemical formula H2SO4. Sulphuric Acid is also known as the king of chemicals due to its immense uses in various industries, especially heavy industries. It is also called matting acid and the oil of vitriol. In the eighteenth century, Sulphuric Acid was produced from green vitriol. The Sulphuric Acid thus developed has an oily look. So, it was then named the oil of vitriol.

 

Sulfuric acid is a mineral acid whose molecular formula contains one sulphur atom, four oxygen atoms with two hydrogen atoms attached directly to two of the oxygen atoms forming the -OH group, hence forming the chemical formula of sulfuric acid is H2SO4. 

It is a colourless, odourless and highly corrosive substance having great commercial importance and is used in most industries. Sulfuric acid is an oily liquid that is inherently vicious as it is highly soluble in water and is an acid rain component as well. 

It is also used as a rust preventive compound for steel and also in large quantities by metal manufacturers. However, sulfuric acid is a dangerous and toxic chemical that can cause inflammation and burns in the airways, nose and throat if inhaled. 

H2SO4 Chemical Name

The chemical name of H2SO4 is hydrogen sulphate or di-hydrogen sulphate. It contains two atoms of hydrogen, one atom of sulphur, and four atoms of oxygen. It has an atomicity of seven.

 

Hydrogen sulphate is basically an ionic bond. The two ions participating in this bond are hydrogen ion (cation) and sulphate ion (anion). 

 

H2SO4 Structure

The Sulphuric Acid structure can be described as follows: –

 

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Properties of Sulphuric Acid 

• Strong Acid: Completely dissociates into ions in its aqueous solution

• Oxidising Agent: It tends to oxidise other substances in a reaction by donating its oxygen atoms. In the following reactions, it oxidises carbon and sulphur. 

2H2SO4 + C —-> 2H2O + 2SO2 + CO2 

2H2SO4 + S —-> 2H2O + 3SO2

• Basicity: The basicity of an acid is the number of hydrogen ions it releases per molecule. Sulphuric Acid is a dibasic acid and releases two hydrogen ions per molecule.

• Dehydrating Agent: Sulphuric Acid has hygroscopic properties, which means that it can attract and retain moisture from its environment. This property makes it a good dehydrating agent as it can take up and retain moisture from the surroundings and keep them dry. 

• It has a high boiling point of 337 °C and a melting point of 10 °C. 

• It turns blue litmus red and has a pH of around one or less.

•  It is highly corrosive, making it dangerous to touch.

In sulfuric acid, there is 1 sulphur atom, 4 oxygen atoms, and two hydrogen atoms that bond directly to two oxygen atoms to form two OH groups. Molecules are covalently bonded and have a tetrahedral structure. 

Molecular Weight of Sulphuric Acid 

The molecular mass is the mass of a substance, which is calculated by adding up the atomic mass of every atom present in one molecule of that substance. 

 

Sulphuric Acid contains three types of atoms, and we need to know the atomic mass of each of those. They are written below.

 

Atomic Mass of Hydrogen = 1 u

Atomic Mass of Sulphur = 32 u

Atomic Mass of Oxygen = 16 u

(Note: The above masses are a good approximation. We have excluded decimals for easier calculation)

 

We know that one molecule of hydrogen sulphate contains two atoms of hydrogen, one atom of sulphur, and four atoms of oxygen, the masses of which are given below.

 

Mass of 2 Hydrogen Atoms = 1 x 2 = 2 u

Mass of 1 Sulphur Atom = 32 u

Mass of 4 Oxygen Atoms = 16 x 4 = 64 u

The molecular mass of hydrogen sulphate is equal to the sum of all its atoms. 

Molecular Mass of Hydrogen Sulphate = 2 + 32 + 64

                                                                     = 98 u

Therefore, the molecular mass of Sulphuric Acid is 98 u. 

 

H2SO4 Molar Mass

Molar mass is the mass of one mole of a substance, measured in grams. One mole of a substance is defined as the Avogadro number (6.023 x 1023) molecules of that substance. 

 

Using the atomic mass of an individual atom and multiplying that by the conversion factor grams per mole (g/mol), you can determine the molar mass of that element.

 

The molar mass constant (our conversion factor) is defined as 0.001 kg/mol or 1 g/mole. Therefore, the Sulphuric Acid molar mass is 98 g/mole. 

 

The molecular formula of sulfuric acid, H2SO4 shows that one molecule of sulfuric acid (H2SO4) contains 2 moles of hydrogen atoms, 1 mole of sulfur, and 4 moles of oxygen atoms. Therefore, the molecular mass of H2SO4 is equal to the sum of the masses of 2 mol of the hydrogen atom, 1
mol of the sulfur atom, and 4 mol of the oxygen atom. The atomic weight of hydrogen is 1u, the atomic weight of sulfur is 32u, the atomic weight of oxygen is 16u, and the molecular weight of sulfuric acid can be calculated as follows. 

Molecular weight of H2SO4 = mass of  2 mol hydrogen atom + mass of 1 mol sulfur + mass of 4 mol oxygen atom 

= (2 × 1) + 32 +( 4 × 16 )

= 2 + 32 + 64 

= 98u 

Therefore, the molecular weight of sulfuric acid is 98u and the molecular weight of sulfuric acid is 98 g / mol. 

Sulphuric Acid Uses

1. It is used to make fertilisers. 

2. It is used in the manufacture of steel and iron. It is also used as a cleaning agent in the industrial sector to erase rust from steel and iron.

3. It is used in the chemical manufacturing industry. It is used to make phosphoric acid, hydrochloric acid, nitric acid, sulphate salts, synthetic detergents, dyes and pigments, explosives, medicines, and ammonium sulphate.

4. It is used for oil processing.

5.It functions as a catalyst in the reaction to convert cyclohexanone oxime to caprolactam. This reaction is used in the production of nylon.

6. It is used to make batteries. In lead-acid batteries, Sulphuric Acid functions as an electrolyte. It can be used in storage batteries. Since it is present in a car battery, it is also known as car battery acid. 

7. In the industry: 

Up to 50% of this produced liquid is used in the production of phosphoric acid, which is used in the production of phosphoric acid fertilizers. It is also used in the manufacture of Pigment, paints, plastics etc, manufacture of metals such as copper and zinc, 5% of the acid produced is used in the production of fibres, the manufacture of explosives and drugs, in leather and petroleum industry etc. It is used in most industries. 

8. At Home: 

It is a very dangerous chemical and should be handled with a lot of care. It is used in acid drain cleaners.  Due to its high drainage, it can be used to remove the tissue paper.  

9. Catalyst: 

It is used as a catalyst in the nylon manufacturing process. Used in the Mannheim process in the manufacture of HCl. 

10. Drugs and Ointment 

It is used to damage the  DNA of cancer cells in the manufacture of chemotherapeutic agents. It is also used in ointments to treat various skin infections. 

Physical Properties of Sulphuric Acid 

1. Pure sulfuric acid is a colourless, odourless, high density, oily liquid with a specific gravity of 1.84 at 288 K. 

2. It is highly soluble in water at all concentrations.

3. It contains 97.3% of acid and boils at 611 K. Therefore, aqueous sulfuric acid cannot be concentrated above 97.3% by boiling. 

4. It will fume in the humid air.  

5. If sulphuric acid touches the skin, it can cause severe burns.

Solved Examples

Question 1. Show the Reaction Between Sulphuric Acid and potassium.

Answer:

Acids react with active metals to form metal salts and hydrogen gas. Potassium reacts with Sulphuric Acid to form potassium sulphate and hydrogen gas. 

H2SO4 + 2K————> K2SO4 + H2