Acid, Base & Salt — Detailed Notes (Page 1: Acids)

Classification of Acids

• Chemically, acids can be grouped into two broad classes based on their source.
  • Organic acids
  • Derived from living organisms, especially fruits & vegetables.
  • Edible and often nutritionally essential.
  • Example: Ascorbic acid $\text{(Vitamin C)}$.
    • Deficiency → disease: Scurvy (bleeding gums, weakness, delayed wound–healing).
  • Mineral (inorganic) acids
  • Obtained from naturally occurring mineral deposits.
  • Typically non-edible and corrosive; can severely damage human tissue on contact.
  • Key examples and their formulae:
    • Hydrochloric acid $HCl$
    • Sulphuric acid $H<em>2SO</em>4$
    • Phosphoric acid $H<em>3PO</em>4$
    • Nitric acid $HNO_3$
    • Perchloric acid $HClO_4$

Ethical & Social Dimension: Acid Attacks

• Mineral acids are sometimes misused in violent crimes ("acid throwing").
  • Consequences: severe burns, permanent disfigurement, psychological trauma.
  • Legal response: very stringent punishment, up to the death penalty.
• Dual harm:
  1. Human suffering.
  2. Wastage of valuable industrial chemicals.
• Suggested civic actions to curb the crime:
  • Public protests & awareness campaigns.
  • Poster distribution to educate communities about hazards & legal stakes.

Everyday & Industrial Applications of Acids

• Domestic / Common-life uses
  • Toilet cleaners → contain strong acids for scale removal.
  • Carbolic acid (phenol) sometimes sprinkled around houses to deter snakes.
• Jewelry manufacture
  • Goldsmiths employ $HNO_3$ for cleaning and refining gold ornaments.
• Energy storage
  • Lead–acid batteries (cars, IPS, microphones, solar-cell banks) rely on $H<em>2SO</em>4$ as electrolyte.
• Digestive physiology
  • Human stomach secretes hydrochloric acid $HCl$ → converts pepsinogen to pepsin & aids protein digestion.

Centrality of Sulphuric Acid $H<em>2SO</em>4$

• Core feedstock for fertilizer production.
• Precursor in manufacturing:
  • Detergents
  • Paints & pigments
  • Pharmaceuticals
  • Insecticides
  • Paper & pulp
  • Explosives
  • Rayon (viscose process)
• Economic insight: Nation’s level of industrialization is often gauged by its annual $H<em>2SO</em>4$ consumption.

Selected Mineral Acids & Specific Roles

• $HCl$
  • Steel pickling (removing rust & oxide scale).
  • Leather processing (tanning preparation stages).
  • Pharmaceutical intermediates.
• $HNO_3$
  • Fertilizer synthesis (e.g.
    ammonium nitrate).
  • Explosives: TNT, nitroglycerine.
  • Metallurgy: leaching to extract gold & other precious metals.
  • Propellant oxidizer in rocket fuels.
• $H<em>3PO</em>4$ (mentioned contextually as mineral acid though individual uses not detailed in transcript; widely used in soft-drinks, rust-proofing, fertilizers).
• $HClO_4$ (powerful oxidizer in specialized industrial labs).

Practical & Safety Takeaways

• Always handle mineral acids with appropriate PPE: gloves, goggles, lab coat.
• Neutralization & proper storage are critical to prevent accidents.
• Public vigilance and education are vital to deter acid-related crimes and encourage responsible industrial usage.