Why does leather get hardened after tanning?
Animal hide is colloidal in nature and has positively charged particles. When it is soaked in tanin (negatively charged), a colloid, it results in mutual coagulation and gets harden. Thus, leather get hardened after tanning.
How does the precipitation of colloidal smoke take place in Cottrell precipitator?
In Cottrell precipitator, smoke particles (charged) are passed through a chamber containing plates with charge opposite to the smoke particles, smoke particles lose their charge on the plates and get precipitated.
How will you distinguish between dispersed phase and dispersion medium in an emulsion?
To distinguish between dispersed phase and dispersion medium we increase the concentration of any one dispersion medium or dispersed phase then notice the change. When dispersion medium is added to an emulsion, it gets diluted to any extent. But on adding dispersed phase it forms a separate layer, if added in excess.
On the basis of Hardy-schulze rule explain why the coagulating power of phosphate is higher than chloride?
Minimum quantity of an electrolyte required to cause precipitation of a sol is called its coagulating value. Greater the charge on flocculating ion and smaller is the amount of electrolyte required for precipitation, higher is the coagulating power of coagulating ion (Hardy-Schulze Law).
Phosphate ion bear - 3 charge while chloride ion carries only -1 charge and due to high charge phosphate ion has high coagulating power than that of chloride ion.
Why does bleeding stop by rubbing moist alum?
Blood is a colloidal sol. When we rub the injured part with moist alum then coagulation of blood takes place. Hence, main reason is coagulation, which stops the bleeding.