Chemistry in Everyday Life looks at the chemicals we use daily and how they work in the body and around us. It covers drugs and how they act on enzyme or receptor targets (antacids, antihistamines, tranquilizers, analgesics, antimicrobials), plus food additives like preservatives, sweeteners and antioxidants, and cleansing agents such as soaps and detergents. For NEET it is a high-yield, mostly fact-based chapter where direct recall of drug classes, examples and definitions fetches quick marks.
Class 12 Chemistry · Chapter 16 – swipe through all 9 cards to understand the whole chapter.
How Drugs Work
Drugs are small chemicals that bind a body macromolecule (enzyme or receptor) to give a biological response.
Selective binding → treats disease with minimal side effects.
- Enzyme targets: drug = inhibitor (competitive at active site vs non-competitive/allosteric)
- Receptor targets: agonist mimics the messenger, antagonist blocks it
- Competitive inhibition is reversed by adding more substrate; non-competitive is not
Four Ways to Classify Drugs
The same drug can be sorted by what it does, how it acts, its shape, or the exact protein it hits.
Classification by molecular target is most useful for medicinal chemists.
- Pharmacological effect: what the patient feels (e.g. all analgesics relieve pain)
- Drug action: the mechanism (e.g. antihistamines act on histamine)
- Molecular target groups drugs by the same protein → same mechanism → guides new drug design
Antacids & Antihistamines
Antacids cut excess stomach acid; antihistamines block histamine’s allergy action.
H1-blocking antihistamines do NOT reduce acid — acid runs through H2.
- Metal hydroxides/NaHCO3 only neutralise acid, don’t control its release
- Cimetidine (Tagamet) & Ranitidine (Zantac) block H2 receptors → stop acid release
- Omeprazole/lansoprazole = proton pump inhibitors; Brompheniramine/Terfenadine block H1
Tranquilizers
Psychotherapeutic drugs that relieve stress, anxiety and mental disease.
Barbiturates (veronal, luminal) are hypnotic/sleep-inducing, not painkillers.
- Antidepressants: Iproniazid, Phenelzine
- Anti-anxiety: Equanil (also lowers high BP), Chlordiazepoxide, Meprobamate, Valium (diazepam)
- Barbiturates are derivatives of barbituric acid; act as hypnotics
Analgesics
Painkillers that reduce pain without unconsciousness, confusion or paralysis.
Morphine relieves severe pain but is addictive; overdose → stupor, coma, death.
- Non-narcotic (non-addictive): aspirin, paracetamol
- Narcotic (opioid): morphine, codeine, heroin — for postoperative/cancer/terminal pain
- Low-dose aspirin reduces platelet aggregation → helps prevent heart attacks
Antibiotics
Substances made wholly or partly by microbes that act against other microbes.
First antibiotic = Penicillin (Fleming); Salvarsan (arsenic, Ehrlich) treated syphilis.
- Bactericidal: penicillin, ofloxacin, aminoglycosides
- Bacteriostatic: tetracycline, chloramphenicol, erythromycin, sulphonamides
- Penicillin G = narrow spectrum; chloramphenicol/tetracycline = broad spectrum
Antiseptics vs Disinfectants
Antiseptics go on living tissue; disinfectants go on non-living objects.
Same substance can be both — strength sets the role.
- Antiseptics: Dettol (chloroxylenol + terpineol), tincture of iodine, 0.2% boric acid (eyewash)
- Disinfectants: 1% phenol; chlorine 0.2-0.4 ppm in water; SO2
- Antiseptic = wounds/skin; disinfectant = floors/instruments — never swap them
Chemicals in Food
Additives preserve, sweeten and protect food without supplying real nutrition.
Aspartame = cold foods only (unstable on heating); sucralose is cookable.
- Preservatives: salt, sugar, sodium benzoate (C6H5COONa), sorbic/propanoic acid salts
- Saccharin & sucralose are heat-stable; aspartame decomposes on heating
- Antioxidants (BHT, BHA, SO2) are oxidised before the food → prevent rancidity
Soaps & Detergents
Cleansing agents have an oil-loving tail and a water-loving head, so they drag grease into water.
Soap fails in hard water (Ca2⁺/Mg2⁺ scum); detergents’ Ca/Mg salts stay soluble.
- Soap = Na/K salt of long-chain fatty acid; cleans by forming micelles
- Detergents: anionic (laundry/toothpaste), cationic (conditioners/germicides), non-ionic (dishwashing)
- Straight-chain detergents are biodegradable; branched-chain are non-biodegradable pollutants
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Frequently Asked Questions
A drug is any chemical of low molecular mass (about 100 to 500 u) that interacts with a macromolecular target in the body to produce a biological response. When a drug is used for the diagnosis, prevention or treatment of disease it is called a medicine, and using chemicals to treat disease is called chemotherapy.
Both kill or stop microorganisms, but antiseptics are applied to living tissue such as wounds and skin, while disinfectants are used on non-living objects like floors and instruments. The same substance can act as both depending on concentration, for example phenol is an antiseptic at about 0.2 percent and a disinfectant at 1 percent.
Soaps are sodium or potassium salts of long-chain fatty acids, made by saponification, which is heating an oil or fat with NaOH to give soap and glycerol. In hard water the calcium and magnesium ions form an insoluble scum with soap, so detergents are preferred because their calcium and magnesium salts stay soluble.
Antacids neutralise or reduce excess stomach acid and raise the pH, for example metal hydroxides or H2 blockers like ranitidine and cimetidine. Antihistamines block the action of histamine at H1 receptors to relieve allergy symptoms, and these H1 antihistamines do not reduce stomach acid because acid release is mediated through H2 receptors.
Yes, it is part of the Class 12 NEET syllabus and is considered scoring because most questions are direct recall of drug classes, named examples and definitions rather than calculations. Focus on classification of drugs, antibiotics versus antiseptics and disinfectants, food additives and the soap versus detergent comparison.