Chemistry in Everyday Life
Easy Overview
That painkiller you took? The soap you used this morning? The preservatives in your food? That's chemistry in everyday life. This chapter is about how chemicals keep us healthy, clean, and fed — and sometimes cause problems too.
Drugs and chemotherapy
Drugs are chemicals that interact with your body's systems. They can kill pathogens (antibiotics), relieve pain (analgesics), or fight cancer (chemotherapy). Most drugs work by targeting specific enzymes or receptors — like a key fitting into a lock. If you can block the right lock, you can control the disease.
Analgesics and antipyretics
Analgesics relieve pain. Antipyretics reduce fever. Aspirin does both — it's an analgesic and antipyretic. Paracetamol (acetaminophen) is another common one. Aspirin works by inhibiting the enzyme that produces prostaglandins (pain-causing compounds). But too much aspirin causes stomach bleeding. Paracetamol is gentler on the stomach but dangerous to the liver in high doses.
Antimicrobial drugs
Antibiotics kill bacteria. Penicillin was the first — discovered by Alexander Fleming by accident in 1928. It disrupts bacterial cell wall synthesis. Human cells don't have cell walls, so penicillin doesn't hurt us — that's what makes it selectively toxic. Antibiotics don't work on viruses. So don't take them for the flu.
Chemicals in food
Preservatives keep food from spoiling. Sodium benzoate and sodium metabisulfite are common. Artificial sweeteners: saccharin (old school), aspartame (diet soda), sucralose (Splenda). Food colors make things look appetizing. Some are natural (turmeric, beetroot). Some are synthetic and controversial. All of them have safe limits set by food authorities.
Cleansing agents
Soaps are sodium or potassium salts of fatty acids. They clean because one end loves water (hydrophilic) and the other loves grease (hydrophobic). Micelles form — the hydrophobic ends grab oil and dirt, the hydrophilic ends face water, and the dirt gets washed away. Detergents are synthetic soaps that work even in hard water.
Key Points
- •Drugs target specific receptors/enzymes in the body
- •Aspirin: analgesic + antipyretic; inhibits prostaglandin synthesis
- •Penicillin: antibiotic that disrupts bacterial cell wall formation
- •Antibiotics don't work on viruses
- •Preservatives like sodium benzoate prevent microbial growth
- •Artificial sweeteners: saccharin, aspartame, sucralose
- •Soap: hydrophilic head + hydrophobic tail; forms micelles to trap dirt
Practice Questions
- Explain how aspirin works as an analgesic and antipyretic.
- What is the difference between soaps and detergents?
- Discuss the role of chemicals in food preservation.
- How do antimicrobial drugs show selective toxicity?
- What are artificial sweeteners? Give examples and their uses.