Everyday Chemistry
Chemistry · रोजमर्रा का रसायन
📋Quick Overview
Chemistry is all around us — from soaps and detergents to medicines and food preservatives. This chapter covers everyday applications of chemistry: cleaning agents, hard vs soft water, water purification, common medicines, and fertilizers. These topics are frequently asked in RRB and SSC exams.
📖Soaps vs Detergents
📖Hard vs Soft Water
- •Hard water contains dissolved salts of Ca²⁺ and Mg²⁺ (calcium/magnesium bicarbonates, sulphates, chlorides)
- •Soft water lathers easily with soap; Hard water does NOT (forms scum)
- •Temporary hardness: due to bicarbonates Ca(HCO₃)₂, Mg(HCO₃)₂ → removed by boiling
- •Permanent hardness: due to sulphates/chlorides CaSO₄, MgCl₂ → removed by washing soda (Na₂CO₃) or ion exchange
📖Common Medicines — Classification
| Type | Function | Examples |
|---|---|---|
| Analgesic | Pain reliever (no loss of consciousness) | Aspirin, Paracetamol, Ibuprofen |
| Antipyretic | Reduces fever | Paracetamol, Aspirin, Ibuprofen |
| Antibiotic | Kills or stops growth of bacteria | Penicillin (Alexander Fleming), Streptomycin, Amoxicillin |
| Antiseptic | Applied on wounds to prevent infection | Dettol, Savlon, Hydrogen peroxide, Iodine (tincture) |
| Antacid | Neutralizes excess stomach acid | NaHCO₃ (baking soda), Mg(OH)₂ (milk of magnesia), Ranitidine |
| Anaesthetic | Causes loss of sensation/consciousness | Chloroform, Ether, Nitrous oxide (N₂O) |
| Antihistamine | Treats allergies | Cetirizine, Diphenhydramine |
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Penicillin — first antibiotic, discovered by Alexander Fleming in 1928 from Penicillium mould. He won Nobel Prize in 1945.
📖Food Preservatives & Water Purification
- •Common food preservatives: Salt (NaCl), Sugar, Vinegar (acetic acid), Sodium benzoate, Potassium metabisulphite, Oil/spices
- •Water purification methods: Boiling, Chlorination (Cl₂ or bleaching powder), Filtration, Distillation, UV treatment, RO (Reverse Osmosis)
- •Alum (Potash alum, K₂SO₄·Al₂(SO₄)₃·24H₂O) is used to settle impurities (coagulation)
📖Fertilizers vs Pesticides
- •Fertilizers provide nutrients (NPK: Nitrogen, Phosphorus, Potassium) to plants for growth
- •Urea [CO(NH₂)₂] = most used nitrogen fertilizer (46% N)
- •DAP (Di-Ammonium Phosphate) = source of N and P
- •Pesticides kill pests; Insecticides kill insects; Fungicides kill fungi; Herbicides kill weeds
- •DDT = first synthetic insecticide (by Paul Muller, Nobel 1948) — now banned (bioaccumulation)