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FILL IN THE BLANKS QUESTIONS, , , , , , , , , , , , , , 1. In adsorption chromatography, the stationa:, phase is and the mobile phase is a y 2 8. ORE eS, Re ne Open ne sed i fh Go, 2. In adsorption chromatography, the distribution a The wt ee, coefficient generally depends upon on and Fetention volume ~, of the substance Of the solution tet, 3. The process of - Occurs when the column 4: Column effeciency Beneralty, $s Uvigated with a solvent: the Fength/ width ratio of eta 5, 4. Solvents are used cither to transfer the mixture! aoe in oo pal, of the column or for bringin about the process mnproves by the panicls, 08 ai oe adsorbent. te, 5. A polar compound is one that is held by..., phase., 6. A non-polar compound tends to move forward, in the .......... phase., , 8. The more polar the adsorbed solute, the .........., the mobile phase must be, if it is going to be, a suitable eluting agent., , 9. Adsorption is generally not suitable for separation of .......... compounds., , 10. Transfer of a mixture to the adsorbent column, is usually carried out by making use of .........., solvent. eee ers, , 11. Adsorption is generally invo i forces _, , Answers : (1) Solid, Gas, Liquid (2) Fa pecsaig ent @G) one, , Stationary (6) Mobile (7) Elution (8) More polar Spanos (16) Increases (17), , Cassar (19) Long (20) Slightly wide (1) Aci, Swonghy (22) Alea, , proportional (19) Long (20) Slightly acidic (2 ‘ _—, , MULTI CHOICE QUESTIONS =, |. Chromatographic analysis was pe sae, by Tswett as an analytical tool for This, of various pigments from plant args pepe, chromatographic technique was Oo ., (a) Adsorption (1 (b) Absorption =, (c) Partition D (d) Ion exchang ;, , 2. For a successful separation by column, , , , , , , , , , , (a) Column dimensions, (b) Mobile liquid phase, (c) Stationary phase O (4) All, , or il vate
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oo —_, wer: Adsorption and partition are based on polarity difference, . in polarity, It becomes more difficult 10 elute very polar Tnotosndds fon doe eteotent, oh, tion 14. Why the general adsorption sequence of functional groups also follows polarity, , + Recause the extent of adsorption can b, nswer ? Because Pulon can be quantitatively predicted according to t ;, follows that solvents will follow a similar polarity order a pS Se Soe, , inf, Fe estion 18, Why adsorption is not generally useful for separation of polar compounds, , Answer: The more polar the adsorbed solute, the more polar the mobile phase must be if it is going, be a suitable cluting agent, In other words, the binding is so strong that the eluting agents do not, possess sufficient polarity to overcome this binding., , Question 16, What is cluotropic series,, , Answer : A grouping of solvents in order of chromatographic strength is called eluotropic senes., , Question 17, What is the basis of separation by adsorption chromatography, , Answer : Separations based on adsorption chromatography depend on the equilibria that govern the, gsiribution of the various solute species between the solvent and the surface of the solid, , 18. Arrange the compounds acid, carbonyl compound, ester, hydrocarbon and alcohol in, , decreasing tendency to be adsorbed,, , Answer : Acid > alcohol > carbonyl > ester > hydrocarbon,, , TRUE / FALSE QUESTIONS, 1. Chromatography is one of the widely used complete elution of the zones., physicochemical methods of separation of in- 9. In general, column adsorption chromatography, organic and organic substances related in their is less difficult to carry out than column parcomposition and properties. tition chromatography., 2 Separation of mixtures by chromatographic 10, Adsorption chromatography is suitable for, methods relies on the distribution of chemical large amounts of sample., species between two phases, a stationary phase ‘ eo : a, and a mobile phase which is allowed to flow Mt. mgainyy adsorption is easier than parti3 omy Se ee. et 12. Polarity increases with an increase in number, . In chromatographic methods separation is gen- of functional groups and decreases with invom achieved through different racngone jhe crease in carbon content,, stationary phase with respect to ‘, and molecules of the mixture concerned, 13. eer sami sequence for an adsorbent fol, 4. Column very, sr ee ee one 14. Anhydrous alumina is a poor chromatographic, of samples. ~, , 5. Chromatographic columns come in different 15. A polarity related factor can be used to corre, late solvents as eluting phases in adsorption, , sizes, shapes, designs,and are made from glass hromatography., , OF some chemical inert material, Compounds containing certain fenctional, 6. The length to diameter ratio of the column — 16 Contos es rcagly adsorbed than others, , should atleast be 10 cm or larger. 17. The nature of adsorbent is influential in deter, 7. If the mixture contains closely related compoRents, long col while chromatography, ; moe reop hyo gegen 18. aeore ‘the separation of a senator, , Tue (8) True (9) True (10) True (11), etme, , , , , , , , , 2 mf, , a =i ail, , b
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1 DANAUS Ag yous ENS}, ID) D |
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= CHROMATOGRAPHY, , and obtain the chromatogram Repeat the experiment using 50% water, 50% ethyl alcohol and 100% Water, eluents. Compare the data for the three eluting agents, SHORT ANSWER QUESTIONS, Question 1, How separation 1s achieved in chromatographic methods, Answer: It is achieved through different sorbability of the stationary phase with respect to the j, and molecules of the mixture concerned. Different sorption degree affects the rate of Passage of the, components, leading to their special separation,, Question 2, Why chromatography ensures 4 more effective separation of substances as Compared to, other methods., Answer : Chromatography is characterised by a very large interface area and a dynamic way Of op., eration, These two features ensure a more effective separation of substances., , Question 3. Give the principle of column chromatography., , Answer : In all applications of column chromatography, the mixture to be separated is introduced a., a small concentrated sample at the top of the column followed by the addition of liquid mobile phase, known as eluting agent. If the separation is due to adsorption, it depends on the interactions between the, solute and the adsorbed surface and the solvent. If the separation is due to partition, it depends on distr,, bution of solute between the mobile and stationary phase., , Question 4. The term chromatography was first proposed by Tswett although it is difficult to define, chromatography in recent years because of variety of systems and techniques to it has been applied., , Answer : The term chromatography means colour writing. In all early applications, the procedure was, limited to the separation of coloured substances that could be identified by their appearance. , Question 5. What is adsorption isotherm., , Answer : The relationship between the concentration of the compound adsorbed to its concentration, in a solvent is given by a curve called an adsorption isotherm., , Question 6. What is the main function of a column., , Answer : To support the stationary phase (adsorbent or stationary liquid on an inert support) and, permit control of solvent input and effluent collection., , Question 7. Give atleast two disadvantages of too long columns., , Answer ; If the column is too long excessive volumes of mobile phase are required before the com, ponents of the mixture emerge from the column, (b) The zone in the column may broden due to diffesioe, in all possible directions,, , Question 8. Although an excessively slow rate of flow can sometimes lead to zone broadening., in general, a slow flow rate is generally preferred over a fast one., , Answer : Too fast flow rate often leads to a non-equilibrium system and extensive tailing., Question 9. What is slurry packing of a column. -», Answer : Column packing dispersed in the eluting agent or sample solvent is called slurry pote, Question 10, Channeled or loosely packed columns provide poor or insufficient separatiom®, Answer : Because the sample and mobile phase seek out the part of least resistance., Question 11, What is the disadvantage of packing the column too tightly., , Answer : Packing the column too tight! f suc, Pressure drop across the column, ely hinders the flow of the motile phase and OOS, , Question 12. The polarity of the mobile phase can be varied widely in adsorption, , Answer : Because miscibility with a stationary liquid, phase is not involved., Question 13. Adsorption is used for non-polar or less polar molecules while pa, , polar molecules., ‘feaime <9 v, , C-108
