கொஞ்சம் கெமிஸ்ட்ரி ! - EP.010

 

Chemical Properties

• Formula: H₂SO₄

• Molar Mass: 98.079 g/mol

• Appearance: Colorless, odorless, and viscous liquid

• Density: 1.8302 g/cm³ (liquid)

• Melting Point: 10.31°C (50.56°F)

• Boiling Point: 337°C (639°F)

• Solubility: Miscible with water, exothermic reaction

• Acidity (pKa): pKa1 = -2.8, pKa2 = 1.99

• Conjugate Base: Bisulfate (HSO₄⁻)

• Viscosity: 26.7 cP (20°C)

• Vapor Pressure: 0.001 mmHg (20°C)

Structure

Sulfuric acid has a tetrahedral molecular geometry with a central sulfur atom bonded to four oxygen atoms. The bond lengths are approximately 142.2 pm for S=O and 157.4 pm for S-O. The O-H bond length is 97 pm.

Preparation

• Contact Process: The most common industrial method for producing sulfuric acid. It involves the catalytic oxidation of sulfur dioxide (SO₂) to sulfur trioxide (SO₃), which is then absorbed in water to form sulfuric acid:

$${\text{<span style="font-family: Diphylleia;">SO</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">2</span>}}<span\; style="font-family:\; Diphylleia;">+</span>{\text{<span style="font-family: Diphylleia;">O</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">2</span>}}<span\; style="font-family:\; Diphylleia;">\to </span>{\text{<span style="font-family: Diphylleia;">SO</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">3</span>}}\backslash text\{SO\}\_2\; +\; \backslash text\{O\}\_2\; \backslash rightarrow\; \backslash text\{SO\}\_3$$

$${\text{<span style="font-family: Diphylleia;">SO</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">3</span>}}<span\; style="font-family:\; Diphylleia;">+</span>{\text{<span style="font-family: Diphylleia;">H</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">2</span>}}\text{<span style="font-family: Diphylleia;">O</span>}<span\; style="font-family:\; Diphylleia;">\to </span>{\text{<span style="font-family: Diphylleia;">H</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">2</span>}}{\text{<span style="font-family: Diphylleia;">SO</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">4</span>}}\backslash text\{SO\}\_3\; +\; \backslash text\{H\}\_2\backslash text\{O\}\; \backslash rightarrow\; \backslash text\{H\}\_2\backslash text\{SO\}\_4$$

• Chamber Process: An older method that has largely been replaced by the contact process. It involves the oxidation of sulfur dioxide in the presence of nitrogen oxides as catalysts.

Uses

• Fertilizers: Sulfuric acid is widely used in the production of phosphate fertilizers, such as superphosphate and ammonium sulfate.

• Chemical Manufacturing: Used in the production of various chemicals, including hydrochloric acid, nitric acid, sulfate salts, synthetic detergents, dyes, pigments, explosives, and pharmaceuticals.

• Petroleum Refining: Employed in the refining of petroleum to remove impurities.

• Metal Processing: Used in the pickling of metals to remove rust and scale.

• Batteries: Serves as the electrolyte in lead-acid storage batteries.

• Cleaning Agent: Used as a cleaning agent in industries to remove rust from steel and iron.

• Catalyst: Acts as a catalyst in various chemical reactions, such as the conversion of cyclohexanone oxime to caprolactam for nylon production.

Safety and Hazards

• Hazard Statements: H314 (Causes severe skin burns and eye damage)

• Precautionary Statements: P260 (Do not breathe dust/fume/gas/mist/vapors/spray), P264 (Wash thoroughly after handling), P280 (Wear protective gloves/protective clothing/eye protection/face protection), P301+P330+P331 (IF SWALLOWED: Rinse mouth. Do NOT induce vomiting), P303+P361+P353 (IF ON SKIN (or hair): Remove/take off immediately all contaminated clothing. Rinse skin with water/shower), P304+P340 (IF INHALED: Remove person to fresh air and keep comfortable for breathing), P305+P351+P338 (IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing), P310 (Immediately call a POISON CENTER or doctor/physician), P321 (Specific treatment), P363 (Wash contaminated clothing before reuse), P405 (Store locked up), P501 (Dispose of contents/container in accordance with local/regional/national/international regulations)

• NFPA 704 (Fire Diamond): 3 (Health), 0 (Flammability), 2 (Reactivity), W (Water-reactive), OX (Oxidizer)

• Lethal Dose (LD50): 2140 mg/kg (rat, oral)

Environmental Impact

Sulfuric acid is a significant environmental pollutant and can contribute to acid rain. It is highly corrosive and can cause severe damage to aquatic life and vegetation. Proper handling and disposal are essential to minimize its environmental impact.

Handling and Storage

• Handling: Use in well-ventilated areas; avoid inhalation and contact with skin and eyes; use appropriate personal protective equipment (PPE).

• Storage: Store in tightly sealed containers made of corrosion-resistant materials; keep away from incompatible substances such as bases and oxidizers.

Historical Background

Sulfuric acid, also known as oil of vitriol, has been known