Surface chemistry deals with the study of the phenomena occurring at the surface of the boundary separating two bulk phases. Adsorption is the process of attracting and holding a substance’s molecules on the surface of a liquid or a solid resulting in a higher surface concentration of the molecules. Adsorbate is a molecule of solid which is adsorbed on the surface and the substance on which it is adsorbed is called adsorbent. Desorption is the removal of adsorbed substances from the surface. Occlusion is adsorption of gases on the surface of solid.
1. Which one of the following is an example of adsorption?
- ammonia in contact with water
- anhydrous CaCl2 with water
- silica gel in contact with water vapours
- all of these
2. At 15oC out of H2, CH4, CO2, NH3, which gas will be adsorbed maximum by charcoal?
3. Which of the following colloids are solvent hating?
- none of these
4. If the dispersed phase is a liquid and the dispersion medium is solid, the colloid is known as
5. The process of separating a crystalloid, from a colloid by filtration is called
6. The movement of colloidal particles towards the oppositely charged electrodes on passing electric current is known as
- Tyndall effect
- Brownian movement
- None of these
7. An emulsifier is a substance which
- stabilizes the emulsion
- coagulates the emulsion
- retards the dispersion of liquid in liquid
- causes homogenesis of emulsion
8. Homogeneous catalysis does mean
- Reactants and goods have to be at the same level
- Catalyst and reactants must be in the same phase
- The reaction mixture must be formed homogeneously during
- The reaction mixture distribution must be homogeneous
9. Which of the following kinds of catalysis can be explained by the adsorption theory?
- enzyme catalysis
- homogeneous catalysis
- acid base catalysis
- heterogeneous catalysis
10. The volume of gases H2, CH4, CO2 and NH3 adsorbed by 1 gm charcoal at 293 K can be given in the order?
- CH4 > CO2 > NH3 > H2
- CO2 > NH3 > H2 > CH4
- NH3 > CO2 > H2 > CH4
- NH3 > CO2 > CH4 > H2