Sulphuric Acid: Structure, Preparation, Properties, Introduction and Uses

How many of you would consider reading a crime thriller or a detective spiel?

I am certain that at least some of you are ultraconservative when it comes to admiring this specific genre of publications! To some extent, bingeing on popular series based on murder mysteries has now become a huge hit among the millennials who are more bound to OTTs of late.

Let me set up a plot for you! A series of disappearing celebrities have been haunting the city cops. They seemed to have been bungling at cracking the case. In fact, the biggest question is- Whether these disappearing stars are dead, or alive. If dead, where are their corpses? With absolutely no clue, a detective is brought to the scene!

Let’s now wrap it up quickly! He discovers that those disappearing celebrities were actually assassinated and to the ultimate horror, their corpse had completely been made to vanish by the killer, using the ‘King of Chemicals’- ‘Sulphuric acid’!

Yes! Indeed sulphuric acid is that powerful!

Well, in reality, several news magazines claimed, and it’s indeed a reality, that sulphuric acid in concentrated form is powerful enough to melt dead bodies completely into liquid. Experiments on pig carcasses, a typical substitute for human bodies, revealed that melting flesh in acid takes days, however, the process may be accelerated by adding water, which dissolves muscle and cartilage in 12 hours and transforms bone to dust in two days. True, this will make a body unrecognisable, but it will not entirely destroy it, at least not in minutes.

TABLE OF CONTENTS

Sulphuric Acid - Introduction
Sulphuric Acid - Structure
Sulphuric Acid - Preparation
Sulphuric Acid - Properties
Sulphuric Acid - Uses
Practice Problems
Frequently Asked Questions - FAQ

Sulphuric Acid - Introduction

Sulphuric Acid (H₂SO₄) is one of the major oxoacids among others like H₂SO₃, H₂S₂O₇ and H₂S₂O₈ etc. The most important and commonly used sulphur oxoacid is sulphuric acid.

Hydrogen sulphate, also referred to as sulphuric acid or oil of vitriol, is a colourless, viscous, caustic, and oily liquid. Due to the massive global production of sulfuric acid, it is referred to be the "king of chemicals."

Jabir ibn Hayyan discovered sulphuric acid in the eighth century. Sulphuric acid consumption per capita has been used to gauge a country's technical progress. The United States, the world's top producer, produces well over 39 billion kg every year. In terms of quantity, it is the most cost-effective acid.

Industrially, H₂SO₄ (hydrogen sulphate) is formed by reacting water with SO₃, which is created by mixing sulphur dioxide and oxygen in a chemical reaction known as the contact or chamber process.

Sulphuric Acid - Structure

Sulphuric acid is a sulphur oxoacid with two oxo and two hydroxyl groups covalently attached to a central sulphur atom. Sulphur is at the centre of a tetrahedral molecule. In sulphuric acid, sulphur is present in its maximum oxidation state, +6. It is a diprotic acid because it can dissociate to give two H⁺ ions. Its n^-factor is 2.

H₂SO₄ ⇌ 2H⁺+SO₄^2-

Sulphuric Acid - Preparation

SO₂ is made by burning sulphur or sulphide ores in the presence of excess oxygen supply (air).

S(s) + O₂ (g) → SO₂(g)

The second step involves the formation of SO₃ when sulphur dioxide reacts with oxygen in a ratio of 1:1 at a temperature of 400 – 450°C and a pressure of 1-2 atm in the presence of V₂O₅ as a catalyst. This is an exothermic as well as a reversible reaction, preferred by low temperatures (optimum) and high pressure.

SO₃ cannot be dissolved directly in water as it leads to the formation of fog. Hence, SO₃ is formed first and it reacts with concentrated H₂SO₄ to give oleum. The oleum obtained is then dissolved in water to obtain concentrated sulphuric acid which is 96-98 % pure.

conc. H₂SO₄ + SO₃(g) → H₂S₂O₇(l) [Oleum]

H₂S₂O₇(l)+H₂O (l) → 2H₂SO₄

Sulphuric Acid - Properties

Sulphuric acid is a viscous and oily liquid.

It has acidic pH. The sulfuric acid used in lead-acid batteries has a pH of 0.5, which is the same as 33.5 % sulphuric acid (H₂SO₄).

Sulphuric acid is also a strong dehydrating agent.

Hot and concentrated H₂SO₄ is a moderately strong oxidising agent. It can oxidise both metals and non-metals, with itself getting reduced to SO₂.

Cu (s) + 2H₂SO₄ (conc.) → CuSO₄(aq) + SO₂(g) + 2H₂O (aq)

S (s)+ 2H₂SO₄ (conc.) → 3SO₂(g) + 2H₂O (aq)

C(s) + 2H₂SO₄(conc.) → CO₂(g) + 2SO₂(g) + 2H₂O (aq)

It undergoes intermolecular hydrogen bonding.

The molar mass of H₂SO₄ is 98.079 g/mol-1 and the equivalent mass is half of the molar mass because its n-factor is 2 as it is a diprotic acid.

It results in a constant boiling mixture. The combination contains 97.3% acid and boils at 338˚C. As a result, boiling cannot concentrate aqueous sulphuric acid beyond 97.3%.

Sulphuric acid also exhibits charring action.

H₂SO₄ is hygroscopic in nature, and hence it can absorb and retain moisture from its surroundings. This property makes it an effective dehydrating agent.

Sulphuric acid ionises in two steps. The higher the Ka value, the stronger the corresponding acid.

H₂SO₄ (aq) + H₂O (𝓁) ⇌ H₃O+ (aq) + HSO₄^-(aq) K_a1= very large (K> 10)

HSO₄^- (aq) + H₂O (𝓁) ⇌ H₃O+ (aq) + SO₄^2- (aq) K_a2= 1.2 × 10^-2

Sulphuric Acid - Uses

Sulphuric acid is a very acidic substance. As a result, it is employed in metal cleaning, oil impurity removal, chemical manufacturing (nitric acid, hydrochloric acid), dye synthesis, pharmaceuticals, detergents, explosives, and so on.

H₂SO₄ is mostly used in the "wet technique" of phosphoric acid production. Phosphoric acid (H₃PO₄) is used in phosphate fertiliser manufacturing. Phosphate rock is used in this process, and roughly 10 crore tonnes are processed each year.

Sulphuric acid is used extensively in the steel and iron industries to eliminate rust and oxidation before exporting their products to the automotive and large appliance industries.

It is the most commonly utilised acid catalyst in the conversion of cyclohexanone oxime to caprolactam, which is used to manufacture nylon.

Sulphuric acid is used in the textile industries to manufacture rayon, a semi-synthetic breathable material used ideally in humid and hot climate zones.

It is used in the Mannheim process to produce hydrochloric acid (HCl).

H₂SO₄ is commonly used in petroleum refining as a catalyst in the reaction of isobutane with isobutylene to form isooctane, a chemical that increases the octane rating of gasoline (petrol).

In the production of chemotherapy medications, it is used to destroy the DNA of malignant cells. It's found in ointments that are used to treat a variety of skin ailments. It is the active ingredient of Debacterol, a topical ointment used to treat cancer sores.

It is used in manufacturing various chemotherapy drugs that are used to treat a variety of malignancies. Cancer cells are eliminated by the breakdown of their DNA during chemotherapy because they are more prone to DNA damage than normal cells. This process is known as the alkylation of DNA, and the chemicals used are known as alkylating antineoplastic therapies.H₂SO₄ is utilised in the production of such types of medicines.

Sulphuric acid is often used as a dehydrating or oxidising agent in industrial processes.

Sulphuric acid is commonly used in acidic drain cleaners, which are used to remove hair, oil, tissue paper, and other debris.

It has a lot of uses in metallurgy. Cleaning metals before enamelling, electroplating, or galvanising is one example.

It is particularly useful in the leather industry, detergent manufacture, and the oil and gas industries.

For research and development, it is the most significant laboratory reagent.

Before harvesting, potato growers employ professionals to spray their fields with a sulphuric acid solution, which causes the green tips to die back and blacken in a day or two. This permits the stems to dry out and not become tangled in the harvesting machinery.

It is also used in wastewater treatment, cleaning agent production, mineral processing, explosives production, detergent production, and aluminium sulphate production in the paper industry.

It is also used to make batteries, detergents like trisodium phosphate, potato cultivation, printing ink, as a dehydrating agent, paper, perfume, disinfectants, and pharmaceuticals, among other things.

Practice Problems

Q 1. The formula of Oleum is expressed as

a. H₂SO₄
b. H₂S₂O₇
c. H₂SO₅
d. H₂S₂O₈
Answer: SO₃ reacts with concentrated H₂SO₄ to give oleum.

Conc. H₂SO₄ + SO₃(g) → H₂S₂O₇ (l) [Oleum].

So, option B) is the correct answer.

Q 2. Name some explosives manufactured using sulphuric acid.
Answer: Explosives manufactured using sulphuric acid are nitroglycerine, trinitrotoluene, and gun cotton. Sulfuric acid is non-combustible, but it is a strong oxidiser that helps other substances burn more efficiently. It is an important sulfonating agent. Also, a mixture of nitric acid and sulphuric acid in concentrated form is used as a nitrating agent which is used to add -NO₂ to a benzene ring.

Q 3. From ancient times, sulphuric acid is also famous as

a. Blue Vitriol
b. Oil of Vitriol
c. Caro’s Acid
d. None of the above.
Answer: H₂SO₄ is also called as oil of Vitriol. Caro’s acid is H₂SO₅. Blue vitriol is CuSO₄.5H₂O.

So, option B) is the correct answer.

Q 4. Concentrated Sulphuric acid is a good

a. Dehydrating agent
b. Hygroscopic agent
c. Oxidising agent
d. All of the above
Answer: Sulphuric acid undergoes intermolecular hydrogen bonding with water. It has a strong affinity for polar water molecules. So, it is a very good dehydrating as well as a hygroscopic agent. Sulphur is in its highest oxidation state of +6. So, it acts as a strong oxidising agent.

So, option D) is the correct answer.

Frequently Asked Questions - FAQ

Q 1. How dangerous is sulphuric acid?
Answer: The corrosive compound hydrogen sulphate (sulphuric acid) is harmful to the skin, eyes, teeth, and lungs. Severe H₂SO₄ exposure can potentially result in death. Workers can be harmed by hydrogen sulphate exposure. The dose, duration, and type of job performed determines the extent of exposure.

Q 2. Why is acid rain containing sulphuric acid harmful?
Answer: If pollution and acid rain were not present, most ponds and lakes would have an pH of around 6.5. Acid rain, on the other hand, has caused many ponds and lakes to have substantially lower pH levels. Furthermore, aluminium that is released into the soil eventually ends up in ponds and lakes. For aquatic animals, the increase in aluminium levels and acidity can be harmful.

Q 3. How is sulphuric acid useful in the paint industry?
Answer: Paints and pigments are made with sulphuric acid. Sulphates, such as barium and lead sulphates, are common pigments in paintings.

H₂SO₄ (dil.)+BaCl₂ (aq)→BaSO₄ (s)↓+2HCl (aq)

Q 4. How is sulphuric acid utilised in metallurgy?
Answer: Sulphuric acid is often employed in the bath in metallurgical operations for the purification of metals by electrolysis. In metallurgy, sulphuric acid is used to convert metals to their sulphates, which are subsequently electrolyzed. In metallurgy, sulphuric acid is used to convert metals to their sulphates, which are subsequently electrolyzed.

Related Topics