Chemistry in Everyday Life: Soaps, Fuels, Plastics, Food Chemistry

Chemistry in everyday life is a high-scoring topic in Kerala PSC exams. Questions test the chemical names, formulas, and uses of common household substances. This note covers everything from soaps to food chemistry.

1. Soaps and Detergents

Feature	Soap	Detergent
Chemical nature	Sodium/potassium salts of fatty acids	Sodium salts of sulphonic acids or alkyl sulphates
Raw material	Animal fats or vegetable oils + NaOH/KOH	Petroleum-based hydrocarbons
Hard water	Does NOT work well (forms scum)	Works well in hard water
Biodegradability	Easily biodegradable	Some are non-biodegradable
Example	Sodium stearate (C17H35COONa)	Sodium lauryl sulphate
Process	Saponification (fat + alkali = soap + glycerol)	Chemical synthesis from petroleum

Types of Soap

Type	Alkali Used	Property
Hard soap (bar soap)	NaOH (sodium hydroxide)	Solid; for bathing and washing
Soft soap (liquid soap)	KOH (potassium hydroxide)	Semi-liquid; for shaving cream, liquid soaps
Medicated soap	NaOH + antiseptic	Contains bithionol or similar
Transparent soap	Dissolved in ethanol	Aesthetic purpose

2. Common Household Chemicals

Common Name	Chemical Name	Formula	Uses
Baking soda	Sodium bicarbonate	NaHCO3	Baking (leavening agent), antacid, fire extinguisher
Washing soda	Sodium carbonate decahydrate	Na2CO3.10H2O	Cleaning, water softening, glass making
Caustic soda	Sodium hydroxide	NaOH	Soap making, drain cleaner, paper industry
Bleaching powder	Calcium hypochlorite	Ca(OCl)2 or CaOCl2	Water purification, disinfectant, bleaching
Plaster of Paris	Calcium sulphate hemihydrate	CaSO4.1/2 H2O	Casts, moulds, chalk
Epsom salt	Magnesium sulphate heptahydrate	MgSO4.7H2O	Purgative, bath salts
Blue vitriol	Copper sulphate pentahydrate	CuSO4.5H2O	Fungicide, electroplating
Common salt	Sodium chloride	NaCl	Food seasoning, preservation
Vinegar	Dilute acetic acid	CH3COOH (4–8%)	Food preservation, cleaning
Lime (quicklime)	Calcium oxide	CaO	White-washing, cement
Slaked lime	Calcium hydroxide	Ca(OH)2	White-washing, water treatment
Marble/Limestone	Calcium carbonate	CaCO3	Construction, antacid

3. Acids and Bases in Daily Life

Common Acids

Acid	Found In	Use
Hydrochloric acid (HCl)	Stomach (gastric juice)	Digestion
Acetic acid (CH3COOH)	Vinegar	Food preservation, cooking
Citric acid	Lemon, orange	Flavouring, preservative
Tartaric acid	Tamarind, grapes	Baking powder ingredient
Oxalic acid	Tomato, spinach	Stain remover
Carbonic acid (H2CO3)	Soda water	Carbonated drinks
Lactic acid	Curd/yoghurt	Fermentation product
Formic acid (HCOOH)	Ant sting, nettle	Causes irritation

Common Bases

Base	Found In	Use
Sodium hydroxide	Drain cleaners	Unblocking pipes
Calcium hydroxide	Lime water	White-washing
Magnesium hydroxide	Milk of Magnesia	Antacid
Ammonium hydroxide	Window cleaners	Cleaning glass
Sodium bicarbonate	Baking soda	Antacid, baking

4. Fertilizers

Type	Examples	Nutrient Provided
Nitrogenous	Urea (NH2CONH2), Ammonium sulphate, Ammonium nitrate	Nitrogen (N) — for leaf growth
Phosphatic	Superphosphate, Triple superphosphate, DAP	Phosphorus (P) — for root growth and flowering
Potassic	Muriate of Potash (KCl), Sulphate of Potash	Potassium (K) — for disease resistance
Complex (NPK)	DAP (Diammonium phosphate), NPK mixtures	Multiple nutrients
Organic	Compost, vermicompost, green manure	All nutrients (slow release)

Fertilizer	Formula	N-P-K Content
Urea	CO(NH2)2	46-0-0
DAP	(NH4)2HPO4	18-46-0
Ammonium sulphate	(NH4)2SO4	21-0-0
Muriate of Potash	KCl	0-0-60

5. Plastics and Polymers

Plastic	Full Name	Uses	Type
PET	Polyethylene terephthalate	Water bottles, food containers	Thermoplastic
HDPE	High-density polyethylene	Milk jugs, pipes	Thermoplastic
PVC	Polyvinyl chloride	Pipes, cables, floor tiles	Thermoplastic
LDPE	Low-density polyethylene	Plastic bags, wraps	Thermoplastic
PP	Polypropylene	Containers, auto parts	Thermoplastic
PS	Polystyrene	Cups, packaging (thermocol)	Thermoplastic
Bakelite	Phenol-formaldehyde resin	Electrical switches, handles	Thermosetting
Teflon	Polytetrafluoroethylene (PTFE)	Non-stick cookware	Thermoplastic
Nylon	Polyamide	Textiles, ropes, toothbrush	Thermoplastic

Thermoplastic vs Thermosetting

Feature	Thermoplastic	Thermosetting
On heating	Softens and can be remoulded	Does not soften; chars
Recyclable	Yes	No
Examples	PVC, polyethylene, nylon	Bakelite, melamine, epoxy
Bonds	Linear/branched chains	Cross-linked networks

6. Fuels

Fuel	Composition	Calorific Value (approx.)	Use
LPG	Butane + Propane	50 MJ/kg	Domestic cooking
CNG	Methane (CH4)	50 MJ/kg	Vehicle fuel
Petrol (Gasoline)	C5–C12 hydrocarbons	45 MJ/kg	Vehicles (SI engines)
Diesel	C13–C25 hydrocarbons	45 MJ/kg	Vehicles (CI engines), generators
Kerosene	C12–C16 hydrocarbons	43 MJ/kg	Lighting, jet fuel
Coal	Carbon (mainly)	25–33 MJ/kg	Power plants, industry
Biogas	Methane + CO2	20–25 MJ/m3	Rural cooking, lighting
Hydrogen	H2	142 MJ/kg (highest)	Rocket fuel, fuel cells

Fuel Facts for PSC

Question	Answer
Highest calorific value fuel	Hydrogen
LPG main components	Butane and Propane
CNG main component	Methane
Octane number measures	Anti-knock quality of petrol
Cetane number measures	Ignition quality of diesel
LPG odour due to	Ethyl mercaptan (added for leak detection)
Incomplete combustion produces	Carbon monoxide (CO) — poisonous

7. Food Chemistry and Preservation

Food Preservatives

Preservative	Chemical	Used In
Common salt	NaCl	Pickles, fish, meat
Sugar	Sucrose	Jams, jellies, murabba
Vinegar	Acetic acid	Pickles, sauces
Sodium benzoate	C6H5COONa	Packaged foods, soft drinks
Potassium metabisulphite	K2S2O5	Squashes, jams
Citric acid	C6H8O7	Soft drinks, canned foods

Food Adulteration

Food Item	Common Adulterant	Detection
Milk	Water, starch	Iodine test (starch turns blue)
Honey	Sugar syrup	Cotton wick test (pure honey burns)
Turmeric	Lead chromate (yellow dye)	HCl test (turns magenta if lead chromate present)
Black pepper	Papaya seeds	Float test in alcohol
Ghee	Vanaspati	Baudouin test

Vitamins — Chemical Names

Vitamin	Chemical Name	Deficiency Disease
A	Retinol	Night blindness
B1	Thiamine	Beriberi
B2	Riboflavin	Cheilosis (cracked lips)
B3	Niacin	Pellagra
B12	Cyanocobalamin	Pernicious anaemia
C	Ascorbic acid	Scurvy
D	Calciferol	Rickets (children), Osteomalacia (adults)
E	Tocopherol	Sterility
K	Phylloquinone	Delayed blood clotting

8. Water Treatment Chemicals

Chemical	Formula	Purpose
Chlorine	Cl2	Disinfection (kills bacteria)
Alum (Potash alum)	K2SO4.Al2(SO4)3.24H2O	Coagulation (settles suspended particles)
Bleaching powder	CaOCl2	Disinfection
Ozone	O3	Advanced disinfection
Activated carbon	C	Removes odour, taste, organic impurities

9. PSC Quick-Fire Facts

Question	Answer
Chemical name of baking soda	Sodium bicarbonate (NaHCO3)
Saponification produces	Soap + Glycerol
Soap does not work in hard water because	Forms insoluble calcium/magnesium stearate (scum)
Most common fertilizer in India	Urea
Non-stick coating is made of	Teflon (PTFE)
Bakelite is a	Thermosetting plastic
LPG leak detected by	Ethyl mercaptan odour
Antacid chemical	Magnesium hydroxide or Sodium bicarbonate
Vinegar is dilute	Acetic acid
Plaster of Paris sets because	Absorbs water and becomes gypsum (CaSO4.2H2O)
Rusting formula	4Fe + 3O2 + 6H2O = 4Fe(OH)3 (simplified: Fe2O3.xH2O)
pH of pure water	7 (neutral)
Acid rain pH	Below 5.6
Blue litmus turns red in	Acid
Red litmus turns blue in	Base
Strongest acid in human body	HCl (in stomach)