Chemistry in Everyday Life
Chemistry in Everyday Life
This domain tests drugs and their targets, food additives, cleansing agents and their mode of action.
Core rules
- Analgesics relieve pain (aspirin, paracetamol); antibiotics treat bacterial infections (penicillin); antacids neutralise stomach acid (ranitidine); antihistamines block histamine receptors.
- Antiseptics are applied to living tissue; disinfectants are used on non-living surfaces.
- Artificial sweeteners include saccharin, aspartame and sucralose. Aspartame is unsuitable for cooking because it hydrolyses.
- Soaps are sodium or potassium salts of fatty acids; they form micelles and emulsify grease.
- Detergents are sulphonates; they work in hard water because their calcium salts are soluble.
- Preservatives (sodium benzoate, vinegar), antioxidants and flavours are food additives.
Worked example Classify aspirin, penicillin, ranitidine and chlorpheniramine. Aspirin is an analgesic and antipyretic; penicillin is an antibiotic; ranitidine is an antacid (H₂-receptor blocker); chlorpheniramine is an antihistamine. Matching each to its pharmacological target avoids the common error of grouping all drugs as antibiotics.
Traps
- Calling all detergents biodegradable; branched alkylbenzene sulphonates are poorly biodegradable.
- Saying soaps work in hard water.
- Confusing antiseptic and disinfectant use.