Chemistry 1 Marks Question

All the particles in a colloidal sol carry the same charge and hence keep on repelling each other and cannot aggregate together to form bigger particles.

Colloidal solutions exhibit Tyndall effect because the size of the colloidal particles (1nm–1000nm) is such that they can scatter light.

If the adsorbate is held on the surface of the adsorbent as a result of chemical reaction forming surface compounds, it is called chemical adsorption.

Emulsions can be diluted to any extent on adding dispersion medium. The dispersed phase forms a separate layer if added in excess.

ZSM–5 (Zeolite Sieve with molecular porosity 5).

Smoke is passed through charged plates so that unburnt charged carbon particles get settled between the charged plate leaving behind air free from pollutants.

Kraft temperature is the minimum temperature above which the formation of micelles takes place.

It is a process by which colloidal solutions containing ionic impurities are purified. The colloidal solution containing ionic impurities is placed in a bag of parchment paper in distilled water in electric field. The ions come out through parchment paper and the sol is purified.

Aquasol and solid aerosol both have solid as the dispersed phase. They differ in dispersion medium. Aquasols have water as the dispersion medium while aerosols have gas as the dispersion medium.

It is important to remove CO in the synthesis of ammonia as CO adversely affects the activity of the iron catalyst, used in Haber’s process.

Higher is the critical temperature of a gas, greater is the ease of liquefication, i.e., greater are the van der Waal's forces of attraction and hence greater is the adsorption.

In this process, colloidal solutions are purified by carrying out filtration through special types of graded filters called ultra-filters. Filter paper allows the passage of electrolyte but does not allow the passage of colloidal particles.

A colloidal solution having water as the dispersion medium and a solid as the dispersed phase is called a hydrosol.
For example: starch sol or gold sol.

A colloidal solution having a gas as the dispersion medium and a solid as the dispersed phase is called an aerosol.
For example: fog.

It is a 4% solution of nitrocellulose in a mixture of alcohol and ether.

Sorption is the process in which adsorption and absorption take place simultaneously, e.g., dyeing of cotton fibres by azo dyes.

Rough surface of a catalyst provides more surface area for adsorption.

White precipitate of silver chloride becomes coloured due to adsorption of pigments of eosin dye.

The movement of colloidal particles under the influence of an applied electric field is known as electrophoresis. Positively charged particles move to the cathode, while negatively charged particles move towards the anode. As the particles reach oppositely charged electrodes, they become neutral and get coagulated.

Electrophoresis is due to charge on colloidal particles, the charged particles move towards one of the electrodes in electric field.

The adsorption of gases on the surface of metals is called occlusion.

Colloids can be classified on various bases:
On the basis of the nature of the interaction between the dispersed phase and dispersion medium, the colloids can be classified as lyophilic (solvent attracting) and lyophobic (solvent repelling).

Adsorption is surface phenomenon therefore adsorption is directly proportional to the surface area.
Finely divided substance has greater surface area. Greater is the surface area of the adsorbent, greater would be its absorbent power. That is why a finely divided surface is more effective as an absorbent.

A catalytic reaction which depends upon the pore structure of the catalyst and on the size of the reactant and the product molecules is called shape-selective catalysis. For example, catalysis by zeolites is a shape-selective catalysis. The pore size present in the zeolites ranges from 260-740pm. Thus, molecules having a pore size more than this cannot enter the zeolite and undergo the reaction.

Ice-cream is an emulsion. Gelatin is emulsifying agent which is used to stabilize the emulsion so it is added to ice-creams.

The process of settling down of colloidal particles i.e., conversion of a colloid into a precipitate is called coagulation.

Common salt (a typical crystalloid in an aqueous medium) behaves as a colloid in a benzene medium. Hence, we can say that a colloidal substance does not represent a separate class of substances. When the size of the solute particle lies between 1 nm and 1000 nm, it behaves as a colloid.
Hence, we can say that colloid is not a substance but a state of the substance which is dependent on the size of the particle. A colloidal state is intermediate between a true solution and a suspension.

Powderded substance are more effective adsorbent than their crystalline forms because when a substance is powdered its surface area increase and physisorption is directly proportional to the surface area of adsorbent

Gelatin stabilises the colloidal solution of gold. Gold sol is lyophobic sol or solvent repelling sol.