Q1.
Can you think of any other coagulation processes used in everyday life?
Answer
Yes — coagulation is at work in the kitchen, at the water works, and even in your own body.
| Everyday process | Coagulant used | What clumps together |
|---|---|---|
| Making paneer or chhena from milk | Lemon juice or vinegar (an acid) | Milk proteins clump and separate from the whey |
| Setting curd from milk | Lactic acid made by the bacteria in the starter | Milk proteins form a soft solid network |
| Purifying drinking water at a water works | Alum (fitkari) | Fine clay and silt particles form settleable flocs |
| Sewage treatment | Alum or other coagulants | Suspended solids settle out before filtration |
| Blood clotting over a cut | The body’s own clotting proteins | Blood cells are trapped in a fibrous mesh, sealing the wound |
| Setting an egg while cooking | Heat | Egg proteins clump into a solid white |
Why a coagulant is needed: The fine particles in muddy water all carry the same kind of electric charge, so they repel one another and stay separated and suspended. A coagulant neutralises that charge. Once the repulsion is gone, particles that collide stick together instead of bouncing apart, and they grow into flocs heavy enough for gravity to pull down. In milk the same idea works through acid: adding lemon juice changes the surface of the protein particles so they stop repelling and clump into paneer.