Chemistry 1 Marks Question

We add alum to purify water as alum coagulates the colloidal impurities present in water, so that these impurities get settle down and remove by decantation or filtration. Thus, water gets purified by adding alum to water.

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.

(a) Colloids have a larger surface area. Therefore, they get easily absorbed and digested.
(b) In emulsion the dispersion medium is a liquid while in gel the dispersion medium is a solid.

Brownian Movement : When viewed through an ultramicroscope, colloidal particles are seen continuously moving in a zig-zag way. Robert Brown in 1827 observed such a movement of pollen grains suspended in water and hence, it is called Brownian movement.

1. Nature of gas, 2. Nature of adsorbent, 3. Effect of temperature, 4. Effect of pressure, 5. Activation of adsorbent.

The number of milligram of a protective colloid which protect 10 mL of a gold sol (containing .06 gram gold per litre) from coagulation on the addition of 1 mL 10% sodium chloride solution.

Invertase, Xymase.

If the solutions are taken in a glass beaker and light is focussed on them, the colloidal solution will scatter light due to Tyndall effect and the path of light becomes visible but no scattering occurs in true solution.

Zeolites are shape-selective catalyst, e.g., a zeolite called ZSM-5 converts alcohols to gasoline.

Effect of pressure : On increasing the pressure of the adsorbate gas the rate of adsorption increases.
Effect of temperature : Since adsorption is an exothermic process so with rise in temperature the extent of adsorption decreases.

During adsorption the residual forces of the surface decreases i.e., surface energy decreases which appears as heat, so it is a exothermic process.

Soap molecules adsorbed on the dirty (oily) surface and try to emulsify it. Soap micelles solubilize the insoluble dirty/greasy material.

Catalyst provide a new path to the reactant molecules which have low activation energy so the rate of reaction becomes fast.

The removal of adsorbed substance from the surface of adsorbate is called desorption.

Adsorption is a surface phenomenon because substance accumulate at the surface.