Surface Chemistry and Colloids - One Line Questions

1. Colloidal particles have a size range typically between: — 1 nm and 100 nm
2. Which of the following is an example of an interface where surface chemistry is relevant? — A solid-gas interface.
3. What is an 'aerosol' in the context of colloids? — A liquid dispersed in a gas.
4. The formation of a colored layer on the surface of a metal when exposed to air is an example of: — Adsorption
5. In adsorption, the substance on whose surface accumulation occurs is termed: — Adsorbent
6. Adsorption is a process where substances accumulate on the surface of another substance. What is the substance that accumulates called? — Adsorbate
7. What is the term for the phenomenon where substances are taken up by the bulk of another substance? — Absorption
8. The formation of micelles by soap molecules in water above the critical micelle concentration (CMC) is an example of: — Colloid formation
9. The Langmuir adsorption isotherm is based on a theoretical model. A key assumption of the Langmuir model is: — Adsorption occurs at specific, localized sites and is reversible.
10. A solid dispersed in a gas, like smoke or dust particles in air, is called a(n): — Aerosol
11. The zigzag, random movement of colloidal particles suspended in a fluid is known as: — Brownian movement
12. Which type of adsorption involves the formation of weak van der Waals forces between adsorbate and adsorbent? — Physisorption
13. According to the Hardy-Schulze rule, for the coagulation of a positive colloid, the coagulating power of anions increases in the order: — Cl- < SO4(2-) < PO4(3-)
14. What is the term for the formation of a gel from a sol? — Gelation
15. The process of destabilizing a colloidal solution by causing the dispersed particles to aggregate and settle down is called: — Coagulation or Flocculation
16. Why do colloidal solutions exhibit the Tyndall effect, while true solutions do not? — Colloidal particles are larger than the wavelength of visible light and scatter it.
17. Which of the following is a method for preparing colloids? — Condensation methods
18. Purification of colloidal solutions from soluble impurities is achieved by: — Dialysis
19. Colloidal particles carry an electric charge. This charge can be positive or negative. This phenomenon is known as: — Colloidal charge
20. Fog and mist are examples of: — Aerosols
21. Which type of colloid is formed when a liquid is dispersed in a solid? — Gel
22. Which factor generally favors physisorption? — Low temperature
23. The enthalpy change during physisorption is typically: — Slightly exothermic (small negative value).
24. When a gas is adsorbed on a solid surface, the entropy of the gas: — Decreases
25. Emulsifiers are substances that help stabilize emulsions. They work by: — Decreasing the interfacial tension and forming a protective layer.
26. According to the Freundlich adsorption isotherm, at very low pressures, the amount adsorbed is approximately: — Directly proportional to pressure
27. Catalysis is often explained in terms of surface chemistry. The catalytic activity of a solid catalyst is due to: — The presence of free valencies on its surface
28. The adsorption of gases on solid surfaces is often described by an equation relating the amount adsorbed to the pressure at a constant temperature. This is known as: — Freundlich equation
29. Ultrafiltration is a technique used to separate colloidal particles from the dispersion medium by using a filter with pores of specific size. These pores are: — Smaller than colloidal particles but larger than dissolved molecules
30. Which of the following is an example of a lyophilic colloid? — Starch sol
31. An example of a 'sol' colloid is: — Paint
32. Hardy-Schulze rule states that for the coagulation of a negative colloid, the coagulating power of cations increases in the order: — Na+ < Mg2+ < Al3+
33. Which method is typically used to prepare colloids like sulfur or arsenic sulfide? — Double decomposition
34. The process of converting a precipitate into a colloidal solution by shaking it with a suitable electrolyte in the presence of a small amount of a new electrolyte is called: — Peptization
35. The Freundlich adsorption isotherm is an empirical relationship. It is expressed as x/m = kP^(1/n). What does 'x/m' represent? — Amount of gas adsorbed per unit mass of adsorbent
36. Which of the following is a common application of adsorption? — All of the above
37. Which of the following is NOT a type of colloid based on the physical state of the dispersed phase and dispersion medium? — Solid liquid
38. Milk is an example of which type of colloid? — Emulsion
39. Lyophobic colloids are generally: — Unstable and require special methods for preparation
40. In the context of colloids, what is the dispersed phase? — The particles that are scattered throughout the medium.
41. What is the dispersion medium in a colloidal system? — The phase in which the dispersed particles are distributed.
42. What is the primary focus of surface chemistry? — The study of chemical reactions and phenomena occurring at interfaces.
43. The Tyndall effect is the scattering of light by colloidal particles. This effect is observed when: — The wavelength of light is comparable to the size of colloidal particles.
44. What is the role of activated charcoal in gas masks? — To adsorb poisonous gases from the air.
45. Which of the following is a difference between true solutions and colloidal solutions? — True solutions do not show Tyndall effect, while colloidal solutions do.
46. When an electric field is applied across a colloidal solution, the charged colloidal particles move towards the oppositely charged electrode. This process is called: — Electrophoresis
47. The process of removing dissolved impurities from a colloidal solution by diffusion through a semi-permeable membrane is called: — Dialysis
48. Chemisorption is characterized by: — Formation of chemical bonds and high activation energy.
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