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UPPCS Chemistry Gap Sheet: Applied Chemicals, Preservation and Explosives.

UPPCS has asked 22 of these. 3 have not been asked yet. Lock the first list, then read the second: it holds what UPPCS has not used yet.

First, the concept

A chemical use follows a mechanism: preservatives slow spoilage, fungicides affect fungi, and photographic salts respond to light. Cold storage slows reactions and microbial growth; it does not sterilise food.

Some substances appear in historical uses that are unsafe or obsolete today. Learn identity and classification without treating them as practical advice. Explosives release energy rapidly; chemical-warfare agents are toxic substances, not necessarily explosives.

✅ Already asked (22)

Preservation and useful chemicals

  • Sodium benzoate · C₆H₅COONa; preservative used in suitable acidic foods and drinks.
  • Benzoic acid · C₆H₅COOH; preservative in suitable acidic products.
  • Refrigeration · Slows biochemical reactions and microbial growth.
  • Pasteurisation · Controlled heating reduces pathogens; not complete sterilisation.
  • Silver bromide · AgBr; light-sensitive photographic material.
  • Silver iodide · AgI; used as a cloud-seeding material.
  • Bordeaux mixture · Copper sulphate and slaked lime in water; fungicide.
  • Ethephon · Releases ethylene; a plant growth regulator associated with ripening.
  • Zinc phosphide · Zn₃P₂; rodenticide, not zinc sulphide.
  • Gammexane · Associated with gamma-HCH, also called lindane; an organochlorine insecticide.
  • Eosin · Dye used in some red inks and biological stains.

Explosive identities

  • Gunpowder · Traditional black powder contains potassium nitrate, charcoal and sulphur.
  • TNT · Trinitrotoluene; explosive.
  • RDX · Cyclotrimethylenetrinitramine; explosive.
  • Nitroglycerin · Glyceryl trinitrate; historically called Nobel oil.
  • Dynamite · Historically nitroglycerin absorbed in a porous carrier.
  • Amatol · TNT and ammonium nitrate mixture.
  • Nitrocellulose · Nitrated cellulose; used in propellants and explosives.

Toxic agents and refrigerants

  • Methyl isocyanate · CH₃NCO; chemical involved in the Bhopal gas disaster.
  • Sulphur mustard · A blister agent; commonly a liquid at room temperature despite the name mustard gas.
  • Sarin · Organophosphorus nerve agent; distinct from mustard agent.
  • CFC refrigerants · Chlorofluorocarbons can damage stratospheric ozone; older refrigerants included CFC-12.

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Preservation and useful chemicals: 3

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⚠️ Silver iodide is used in cloud seeding; silver bromide in photographic emulsions. MIC is isocyanate, not isocyanide.

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