Give reason why addition of alum purify the water
Answers
Answer:
Alum has a negative charge and tends to disperse in water very fast and very well (Because it's a colloid).
This causes it to join up with all of the offending particles and neutralize them. Now that the particles don't have any repelling charges, they tend to clump together into 'flocs'.
The increased size as well as the lack of repelling charges cause the alum particles to settle down at the bottom or rise up and float in the water.
After the particles are neutralized, they clump together because of the London Dispersion Force which are part of the Van der Waals forces. Basically, weak intermolecular force arising from quantum-induced instantaneous polarization multipoles in molecules causes even nonpolar particles to attract each other due to the correlated movements of the electrons in interacting molecules. Then they settles down.
Explanation: the alum is needed to add in impure water becoz
- the particles are all similar and ionized so therefore they have a similar charge(positive) causing them repel each other and stay separate
- And becoz they are so small the gravitational force acting on them is not very strong either.
- Also the dust particles previously disappeared in the air have lot of kinetic energy already