Sulphuric Acid – Structure, Properties and Molecular Weight
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
Pure sulfuric acid is a colourless, odourless, high density, oily liquid with a specific gravity of 1.84 at 288 K.
It is highly soluble in water at all concentrations.
It contains 97.3% of acid and boils at 611 K. Therefore, aqueous sulfuric acid cannot be concentrated above 97.3% by boiling.
It will fume in the humid air.
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
FAQs on Sulphuric Acid
1. Write the Chemical Formula of Sulphuric Acid
Chemical formula of Sulphuric Acid is written as H2SO4.
2. How can we neutralise Sulphuric Acid?
Pouring the baking soda straight into the acid will neutralize light acids such as vinegar and toxic strong acids such as hydrochloric acid and sulfuric acid.
3. What are the uses of Sulphuric Acid?
Sulphuric acid is used widely in various industries, homes and laboratories. It is used as a rust preventive compound in metal industries, used in the manufacture of paint, dye, pigments, used in the cleaning agents, used in the manufacture of fertilizers as well. These are a few common places where Sulphuric acid is highly used.
4. Is Sulphuric Acid dangerous for human beings?
If concentrated sulfuric acid accidentally adheres to skin, clothing and wood, it can cause severe skin burns, puncture clothing and burn wood and cause black stains on the surface.
5. What happens if one inhales Sulphuric Acid?
Its vapour is strongly irritant to the respiratory tract and can cause sore throat, coughing, shortness of breath, laboured breathing.
6. When diluting Sulphuric Acid, why should we put the acid into the water? Why not the other way round?
The reaction of acid and water leads to a decrease in the concentration of ions (H3O+) per unit volume. This process is referred to as dilution. This is a highly exothermic reaction.
If we add the water into the acid, a highly concentrated solution of acid is formed first, which releases a tremendous amount of heat. This heat makes the acid bubble, and splash. This can cause severe burns and injury. It might even break the glass container in which it is held.
If we add acid to the water, a much lesser amount of heat is generated at first, and this heat is also absorbed by the water, which is a much safer process of dilution. Hence, when diluting Sulphuric Acid, we should always put the acid into water, never the other way round.
7. In the event of an acid spill, how can we neutralize Sulphuric Acid?
Add the baking soda directly to the acid spill. It can neutralise mild acids such as vinegar and even dangerous acids such as muriatic and Sulphuric Acid s. Drench the entire polluted surface with baking soda (sodium bicarbonate, NaHCO3) to neutralise the acid.