Buku G.S. Manku Chapter 8 [PDF]

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,4cidt and Bases 271



ll'



(b) NH3, NCla, NFei (c) pyridinc, 2-mcthylpyr.idinc, 3-chloropyridincl (d) NHs, HN(CI{3)2, CHsNHx and (CH3)3N; (o) NRs, whon R : Mo, Et, frr, Uu, iso-pr, frir, aud /"8u. ExlainwhyNhollisilstl'orBbasc,silol.l)a is a rvcak aci.r arrd



o3cloll is



B Redor Systems



a



stronq acid. 12. "Alkalis, oxyacids and amphoterio hydrbxides contain one or ,r'ore oH groups attached to x as x'-o*H".,why is trrcre any dilTcrencc in their bchaviourl 13. why does the prescncc of keto oxygcn increase tho acidity ol' an oxyacid trcmendously, wheroas that of OH doos not? 14. w'hy docs tho acidic charactor ol'hydracids decreasc rvith tho increasing elcctronegativity of notunotal, and that of oxyacids increase? t5. Discussthosignificnncoofthoinductivsandrosonancccflcctsin ths acid strcngth ol'tlro organic carboxylic acids and phenols. 16. Givo suitablo oxamples to demoostrato tho eftbct of the F, B and strain in the molcculos, with relbrence to tho Lowis charactcr. 17, why arc phenols best lbr studying tho effects of electron-withdrawing groups, whereas benzoic acids aro best tbr such studies for the clectron donor groups? 18. Ilbw doos solvolysis allbct tho rcid.baso proportios of compounds? 19. Tho successive hydrolysis condtants for tho metal ious do not change much. For



I



HE2*, tlroso valucs aro 3.70 nnd



20.



21. 22. 23, 24. 25, 26.



to 30. 31.



2..60;



for Zr(lV),O.22,0.62, l.0ianrl



l.l?(pi



vnlucs). Give rcnsons rvhy. Tho hydrolysis constants lbr thc mctal ions having diffsrcnt chargcs arc quitc diftbrcnt. Why? why aro BFs and sFs inert towards hydrolysis, while BCl3 and TbF6 undcrgo roady hydrolysis? What is Poarson's htrd nnd solt acid and basc (HSAI,) conccpt? What aro tho charactcristics ol' a hard acid and a lrard basc? what.arc thc chnrflcteristics of a sot't acid and a soft base? why is mcthylmercury c&tion chosen as the standard lbr the evaluation of the hardness or sol'tn:ss of a base? W'hy is pyridino bordcrlilro baso whilo anrmonia a hnrd basc? Why does CsF roact with Lil, cvcn though both arc ionic? What is synrbiosis? Whnt aru its tpplications? What are thc two currcnt theories prcvailing lbr the IISAB concopt? '. Whnt are thc litnitntlons of tho HSAB conccpt? Explal. thb tcrrn co4iugato acids nrrd cor{ugatc bascs with suitablo cxamplcs. Arrango tho lbllowing in o-rdet of incrcasing acid strength: rsobrrtyric acid, propionic acid, 3-chloropropionic acid and 2rohloropropionic acid. _



l



.



The term oxidotiortwas originally used



il;;;;;;#ffi'o*re.nl



to



represent\



a



process



in



achemical reaction and the t"try



rvas used i6r a]6Eess in wlrich oxygen was rem GFGiffiiocesscs Today tlrese terms ate used



to



which



a



rylyltlu



in *J'ith,,:)(J8,t:.]y1 ill!9IS



wt,utro.u.r. ltedox rcacliols 3rs norv dcscrib:4-



;;;ir;;;r;ot. asa



aS,ents or accept electront are termed .as oxidizing place take reduction''cannot iitair,t.Thc two pto".stit of oxidation and a reaction' in separatcly, but trrttst occur simultancottsty



aod substancc



s thut



HALF.REACTIONS



are called Reactions that involve donation or acceptanc; of the electrons are^also agents'.These oxidizipg or rcducing half-reo.crions for the resPective place at the take can reactions partial These ion-elecyon reaclions. called the species' The electrodes which can supply and remove the electrons from half'reactionsthe of sum ttet overal[ reclox reaction can be written as the the other (reductiorl)-and gain electrons o[ one flor the oxidant lepresenting rcaclion between and (t{.2): Fe3+ Sn2+



'-F



(8.1 )



Fcil+



Snr+



+-



2e-



(8.2)



.E I



Rcdo.v



Systens



2?3



2Fegr



*



Sns+



-'



!psr+



f



gxr+



(8.3) Rcdox reactions can be carried out in spaces separated from each other, the reactants being ,inked only through an eiectric connection, as in a galvanic cell' The rcclox systems



into two harf'reactions. such a



can always, conceptualry, be system:has an advantagein



the redox reactions, and m.ore imporiantly and reducing strcngths of diffcreni specics.



ii-14



(l)



separated barancing



.o,rporing the oxidizing



of



harf-reactions, the



r' (t) Identification oxidizing and tbe reducing species. t/ (2) writing down ofthethehalf-reactiin molccules involved in the reaction. balanced by using free electrons (hence,



oxfficriorr:



thc oxidatio'



of iodide ions lry



hydr.o-ren per.



I- -+ Ie is oxidation, ON changcs from _ I to 0, HrA2 1 llrO is rcduction, ON of O atoru cbanges froru _l to _2. Each'of thcse two half-reactions nrust be balancccj. Hcucc,



2I^ Fl Iz -F 2e-.



(8 4)



is obtained by balancing rhe electric charges by adding two-ttr. . This crectrorrs to thc riglrt hancl sidc (RI{SJ of rhe .q*,ior, ufi., puri;rg .ar,. number of iodine atoms on both sides. For the other harf.reaciion. ions in tlte nredium 1ll'r'hcrc, not undcrgoing rcdox rcaction) have t