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(i) Explain Intermediatecompound formation theory (ii) Writeshortnoteson ultra filtration |
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Answer» Solution :(I) The intermediatecompound formation theory : A catalyst actsby providinga new pathwith lowenergyof activation . In homogeneouscatalysedreactions a catalyst maycombine with one or more reactantto forman intermediatewhich reats withother reactant or decomposeto giveproducts and the catalyst is regenerated . Consider the reactions : ` A + B to AB ` A + C ` to`AC ( intermediate ) C is thecatalyst ` AC + B to AB + C` Activation energies for THEREACTIONS (2) and (3) areloweredcomparedto THATOF (1) . Hencethe formation anddecompositionof the intermediateaccelerate rate of the reaction . Examples : The mechaismof Fridealcraftsreaction is givenbelow : `C_(6) H_(6) + CH_(3)CIoverset("anhydrous")overset(AlCI_(3))toC_6H_(5)CH_(3) + HCI` The action of catalyst is explained as follows ` CH_(3)CI + AICI_(3) to[CH_(3)]^(+) [AICI_(4)]^(-)` It is an intermediate ` C_(6)H_(6)+ [CH_(3)^(+)] [AICI_(4)]^(-) to C_(6)H_(5)CH_(3) + AICI_(3) + HCI` (ii) Ultrafiltration (i) The pores of ordinary filterpaperspermit the passageof colloidalsolutions (ii) In ultrafiltrations , the membranes are made by usingcolloidion cellophane or visiking (iii) Whena colloidalsolution is filtered usingsucha filter, colloidalparticlesare separatedon thefilter and theimpuritiesare removedas washings. (iv) The processis QUICKENED by APPLICATION of pressure. (v) THe separation of sol particlesfromelectrolyte by filteration through an ultrafilter is called ultrafilitration . |
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