7a7a.docx

E3mar

Question 1 (Colloids)

Amr Gamal

Write (T) for true statements and (F) for false one 1. CMC are Example for Coarse dispersion 2. Colloidal dispersion form True solution 3. A colloidal dispersion can be separated from a coarse dispersion by filtration 4. A dispersion of particle size less than 1nm can be seen under electron microscope 5. dispersion of water in oil or oil in water are examples of lyophobic colloids 6. the process of dialysis can be hastened by applying potential difference with renewing the outer liquid from time to time 7. Sulphur is dissolved in water then by adding alcohol give colloidal Sulphur 8. cations are less hydrated than anions 9. Stern potential called Nernst potential 10. the potential at surface layer called zeta potential and measured by zeta meter 11. by increasing zeta potential, stability decreases 12. decrease zeta potential means that repulsion force is more than attraction force 13. Ca+2 as electrolyte increase in stability of colloidal system more than Na+ 14. movement of charged particles through liquid under the effect of applied potential difference called electro-osmosis 15. according to Brownian motion, by increasing particle size, velocity increases 16. True solution scatter light and appear clear while colloidal not 17. Both Repulsive force and attraction force are inversely proportional to distance between particles 18. Attraction force called energy barrier 19. Amino acids exhibit only negative charge upon hydrolysis 20. Amino acids exhibit only negative charge upon hydrolysis in acid media 21. Amino acids exhibit only positive charge upon hydrolysis in acid media 22. electrostatic stabilization Involve adding polymer to system which adsorb surface and prevent the particles coming into close contact 23. Because of their size they may be separated from molecular particles by technique of separation called diffusion 24. In case of normal micelle, both oil soluble and water-soluble drugs can be used ‫مهمه‬ 1

E3mar

Question 1 (Colloids)

Amr Gamal

Answers 1 F 11 F 21 T

2 F 12 F 22 F

3 T 13 F 23 F

4 F 14 F 24 F

5 T 15 F

6 T 16 F

7 F 17 T

Choose the correct answer 1.To impart a negative charge to AgI colloid the following method use a) b) c) d) e)

Colloidal mill ion dissolution Dispersion method Add excess NaI Both b and d

2. To prepare acacia colloidal dispersion the following method used a) b) c) d) e)

ultrasonic treatment Electric arc crystallization All the above None of the above

3. Addition of sodium thiosulphate will produce a) b) c) d) e)

Colloidal cupper Colloidal sulphur Coarse precipitate H2 S Na2So4

4. in order to hasten the dialysis process, one of the following is true a) b) c) d) e)

Stirring Addition of colloids Use of molecular dispersion a and b b and c 2

8 F 18 F

9 F 19 F

10 F 20 F

E3mar

Question 1 (Colloids)

Amr Gamal

5. one of the pharmaceutical applications of dialysis is a) b) c) d)

artificial kidney machine artificial membrane preparation of colloids all are true

6. Micelle aggregates of non-ionic surfactant in non-polar solvent considered as ‫مهمه‬ a) b) c) d) e)

Association colloids Inverted micelle Normal micelle All are true a and b

7. If zeta potential of a colloid is +70, this indicates a) b) c) d) e)

Low stability Moderate stability Both a and b High salt concentration None of the above

8. Addition of calcium chloride to colloidal preparation can: a) b) c) d) e)

Increase stability Reduce zeta potential twice the effect of sodium chloride Shrink the double layer thickness All are true Only b and c are true

9. Steric stabilization of colloid involves a) b) c) d) e)

NaCl addition Thickening of double layer Addition of polymer Increase in zeta potential a and c

10. One of the following is considered true about colloids a) Diffuse rapidly 3

E3mar b) c) d) e)

Question 1 (Colloids)

Amr Gamal

Size is greater than 1 um Show Tyndall effect Don't scatter light Coagulate with polymer

11. An electric potential may be used to increase the rate of movement of ionic impurities through a semipermeable membrane, this technique called a) b) c) d)

Electro dialysis Dialysis Electro-osmosis Electrophoresis

12. Regarding the following reaction: AgNo3 +Nal  AgI+ NaNO3 if the reaction is carried out with excess silver nitrate a) b) c) d)

The colloidal particle will assume a positive charge The colloidal particle will a negative charge The colloidal particle will be surrounded by positively charged ions B and c

13. Solution of protein and starch in water are examples of a) b) c) d)

Lyophilic colloids Lyophobic colloids Hydrophilic colloids Hydrophobic colloids

14. The movement of a charged particle through a liquid under the influence of an applied potential difference is known as a) b) c) d)

Zeta potential Streaming potential Electrophoresis Electro-osmosis

15. Brownian movement of particles ‫مهم‬ a) b) c) d)

Assist sedimentation Prevent sedimentation Increase sedimentation Doesn't affect sedimentation 4

E3mar

Question 1 (Colloids)

Amr Gamal

16. Maximum sedimentation volume is obtained when zeta potential is a) b) c) d)

Zero Negative Positive None of the above

17. Which of the following cannot form colloid spontaneously? a) b) c) d)

Lyophilic colloids Lyophobic colloids Micelle colloids Association

18. In the DLVO theory, normal thermal motion may be sufficient to overcome the energy barrier that leads to irreversible particle aggregation the name of this energy barrier is which of the following a) b) c) d)

Primary minimum Primary maximum Secondary minimum Secondary maximum

19. The difference in potential between the actual surface and the electro neutral region of the solution a) b) c) d)

Electro kinetic potential Nernst potential Electro dynamic potential b and c

20. Brownian motion can be increased by a) b) c) d)

Increasing the viscosity of the dispersing phase Decreasing the radius of particles Increase the particle size a and b

21. The addition of electrolyte to colloidal solution will cause a) Compression of the double layer b) Increasing the zeta potential 5

E3mar

Question 1 (Colloids)

Amr Gamal

c) Deeping the primary maximum d) Lowering the secondary minimum 22. Can pass through filter paper a) b) c) d) e)

Colloidal dispersion Molecular dispersion Coarse dispersion a and b b and c

23. all of the above are examples of colloidal dispersion except a) b) c) d)

protein gum acacia insulin RBCS

24. By sheathing coarse materials between stationary cone and rapidly rotating cone of Colloidal mill, this method called a) b) c) d)

Colloidal mil Condensation method Electric arc None of the above

25. ………. Is used in syphilis treatment a) b) c) d)

Colloidal cupper Colloidal mercury Colloidal gold Colloidal calomel

26. indicate which of the following statement is true when electrolyte is added to coarse to coarse dispersion a) b) c) d)

The double thickness around particles increased Repulsion between particles increase Van der walls forces between particles are decreased The height of primary maximum is decreased

6

E3mar

Question 1 (Colloids)

Amr Gamal

27. light scattering in colloid system is known as a) b) c) d)

Brownian Tyndall effect Coagulation Electrophoresis

1 E 11 A 21 A

2 E 12 A 22 d

3 b 13 a 23 d

4 a 14 c 24 a

5 a 15 b 25 b

6 e 16 a 26 d

Compare 1. Molecular dispersion and Colloidal Dispersion 2. Coagulation and flocculation 3. Electrophoresis and Electro-osmosis Write short notes about Electric double layer with drawing

7

7 e 17 b 27 b

8 e 18 b

9 c 19 d

10 c 20 B