Sulfuric Acid | Formula | Properties | sulfuric acid uses in industry

Sulfuric Acid

Organic name- Sulfuric Acid (American) or Sulphuric Acid (British)

Molecular formula – H₂SO₄

Strength – Very Strong Acid

Sulfuric acid also known as vitriol oil, is a mineral acid composed of the molecular formula H₂SO₄ with sulfur, oxygen, and hydrogen components. It is a colorless, odorless, and smooth liquid that is soluble in water and synthesized in a reaction that is highly external.

Sulphuric Acid formation

Pure sulfuric acid is not found naturally on earth in the form of anhydrous because of its extreme affection for water. Dilute sulfuric acid is a component of precipitation that is formed by atmospheric oxidation of sulfur dioxide in the presence of water - i.e. oxidation of sulfuric acid. Sulfur dioxide is the main by-product when sulfur-containing fuels, such as coal or oil, are burned.

Sulfuric acid is naturally formed by the oxidation of sulfide minerals such as iron sulfide. For this reason, water can be highly acidic and is called acid mine drainage (AMD) or acid rock drainage (ARD). This acidic water is able to dissolve the metals present in the sulfide ores, resulting in a brightly colored, toxic solution.

The first step is to burn sulfur to make sulfur dioxide.

S (s) + O₂ → SO₂

Sulfur dioxide is oxidized to sulfur trioxide by oxygen in the presence of the vanadium (V) oxide catalyst. This reaction is the opposite and the formation of sulfur trioxide is extrinsic.

2 SO₂ + O₂ ⇌ 2 SO₃

Sulfur trioxide is absorbed in the formation of oleum (H₂S₂O₇) in 97-98% H₂SO₄, also known as sulfuric acid fumigation. Oleum then mixes with water to form a concentrated sulfuric acid.

H₂SO₄ + SO₃ → H₂S₂O₇

H₂S₂O₇ + H₂O → 2 H₂SO₄

Directly dissolving SO₃ in water is not practiced.

Properties of sulphuric acid

i. Although nearly 100% of sulfuric acid solutions can be made storage concentration is 98.3%.

ii. 10M sulfuric acid is prepared by slowly adding 98% sulfuric acid to an equal volume of water, with good stirring, the temperature of the mixture can rise to 80 °C or higher.

iii. Pure sulfuric acid has a vapor pressure of <0.001 mmHg at 25 °C and 1 mmHg at 145.8 °C.

iv. Pure sulfuric acid is a viscous clear liquid, like oil, and this explains the old name of the acid.

v. Commercial sulfuric acid is sold in several different purity grades. Technical grade H2SO4 is impure and often colored but is suitable for making fertilizer. Pure grades, such as United States Pharmacopeia (USP) grade, are used for making pharmaceuticals and dyestuffs. Analytical grades are also available.

vi. Melting point 10.31°C and boiling point 337°C.

vii. It is a clear, colorless, and odorless liquid.

viii. It is a non-flammable chemical

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ix. It reacts with most bases to give the sulfate salt and water.

x. The hydration reaction of sulfuric acid is highly exothermic.

xi. It reacts with its anhydride, SO3, to form H2S2O7 and it is called pyrosulfuric acid or fuming sulfuric acid.

xii. Anhydrous H2SO4 is a polar liquid with a dielectric constant of about 100.

xiii. It attacks reactive metals like iron, aluminum, zinc, manganese, magnesium, and nickel and produces hydrogen gas and its salts.

Reaction with Water

Since the hydration reaction of sulfuric acid is highly exothermic, it should always be reduced by adding acid to water rather than acid. Because the reaction is a balance that supports the rapid persuasion of water, the addition of acid to the water ensures that the acid is a limiting reagent. This reaction is best understood as the formation of hydronium ions:

H₂SO₄ + H₂O → H₃O⁺ + HSO₄^-   Ka₁ ≈ 10³ (strong acid)

HSO₄^- + H₂O → H₃O⁺ + SO₄^2-    Ka₂ = 1.0×10⁻²

HSO₄^- is a bisulfate anion and SO₄^2- is a sulfate anion. Ka₁ and Ka₂ are the acid dissociation constants.

Sulfuric acid uses in industry

i. Most of the amount of sulfuric acid is used for industrial purposes.

ii. About 60% of the amount is consumed for fertilizers, especially superphosphates, ammonium phosphate, and ammonium sulfate.

iii. About 20% of sulfuric acid is used in the different chemical industries for the production of products like detergents, synthetic resins, dyestuffs, pharmaceuticals, petroleum catalysts, insecticides, and antifreeze.

iv. It is used for about 6% are related to pigments including paints, enamels, printing inks, coated fabrics, papers, and others.

v. It is widely used by the iron and steel-making industry to remove corrosion, rust, and scaling from rolled sheets and billets before their sale in the automobile and major equipment industries.

vi. High-concentration sulfuric acid is often the main ingredient in acidic drain cleaners used to remove grease, hair, tissue paper, etc.

Safety

Sulfuric acid is capable of causing extremely intense combustion, especially when it is of high concentration. Common with other corrosive acids and alkalis, it easily decomposes proteins and lipids through amide and ester hydrolysis after contact with living tissues such as skin and flesh.