Surface Chemistry Exercises

University:
Minnesota State University Moorhead
Course:
CHEM-150 | General Chemistry I
Academic year:

2022
Views:

214

Pages:

2
Author:

Hidalgokr1

SURFACE CHEMISTRY EXERCISE – I Q.1 UNSOLVED PROBLEMS Illustrate with examples : (i) Lyophillic and lyophobic solutions, (ii) Multimolecular and macromolecular colloids. (iii) Homogeneous and heterogeneous catalysis. Q.2 What are the two classes of emulsions ? Give one example of each class. State one activity to test the type of an emulsion. Q.3 How do size of particles of adsorbent, pressure of gas and prevailing temperature influence the extent of adsorption of a gas on a solid? Q.4 Explain the following observation: (a) Lyophilic colloid is more stable than lyophobic colloid. (b) Coagulation takes place when sodium chloride solution is added to a colloidal solution of ferric hydroxide, (c) Sky appears blue in colour. Q.5 What is meant by adsorption isotherm ? What is the effect of pressure on physical adsorption? Explain freundlich adsorption isotherm Q.6 (a) What are micelles ? How do they differ from ordinary colloidal particles ? Give two example of micelles forming substances. (b) State Hardy-Schulze rule. Q.7 Define adsorption. Write any two features which distinguish physisorption from chemisorption. Q.8 Explain the following terms with a suitable example in each case: (i) Shape - selective catalysis (ii) Dialysis (iii) Emulsification (iv) Tyndall effect Page # 79 SURFACE CHEMISTRY EXERCISE – II BOARD PROBLEMS Q.1 What causes Brownian movement of a colloidal solution? Q.2 Which has a higher enthalpy of absorption physisorption or chemisorption? Q.3 Describe electrophoresis briefly. Q.4 Why does physisorption decrease with the increase of temperature Q.5 In chemisorption why x/m initially increases and then decreases with rise in temperature? Q.6 Distinguish between homogeneous and heterogeneous catalysis. What role does adsorption play in heterogeneous catalysis? Q.7 Distinguish between micelles and colloidal particles. Give one example of each. Q.8 What is the 'coagulation process? Q.9 What happens in the following activities and why? Q.10 (i) An electrolyte is added to a hydrated ferric oxide sol in water. (ii) A beam of light is passed through a colloidal solution. (iii) An electric current is passed through a colloidal solution. Describe the following: (i) Q.11 Tyndall effect (ii) Shape-selective catalysis What is meant by coagulation of a colloidal solution? Name any method by which coagulation of lyopholic sols can be carried out. Q.12 Define the following (i) Peptization Q.13 (ii) reversible sols Classify colloids where the dispersion medium is water. State their characteristics and write an example of each of these classes. Q.14 Explain what is observed when (i) an electric current is passed through a sol (ii) a beam of light is passed through a sol. (iii) an electrolyte (say NaCl) is added to freeic hydroxide sol. Q.15 Define 'peptization'. Q.16 Write three distinct features of chemisorptions which are not found in physisorptions. Q.17 What is meant by coagulation of a colloidal solution ? Name any method by which coagulation of Q.18 lyophobic sols can be carried out. What is especially observed when a beam of light is passed through a colloidal solution ? Q.19 Define the following terms with an example in each case : (i) Macromolecular sol (ii) Peptization (iii) Emulsion