Amitwantedtorenovate hisoffice.Hewantedto installdoors/ windowsmade up of ironbut hisfriendsuggestedhimtouse windows/doorsmade upofaluminium. Amitaccepted thesuggestionofhisfriend. Afterreadingthe abovepassage,answerthe followingquestions : (i) Whatvaluesaresuggested byAmit'sfriendwhichchangedhismindtousewindows/doorsmadeup ofaluminium insteadoriron ? (ii) Giveone principleoreeachofironandaluminium. (iii) How isironandaluminiumobtainedfrom theirrespectiveores ?

Amitwantedtorenovate hisoffice.Hewantedto installdoors/ windowsmade up

1.	Amitwantedtorenovate hisoffice.Hewantedto installdoors/ windowsmade up of ironbut hisfriendsuggestedhimtouse windows/doorsmade upofaluminium. Amitaccepted thesuggestionofhisfriend. Afterreadingthe abovepassage,answerthe followingquestions : (i) Whatvaluesaresuggested byAmit'sfriendwhichchangedhismindtousewindows/doorsmadeup ofaluminium insteadoriron ? (ii) Giveone principleoreeachofironandaluminium. (iii) How isironandaluminiumobtainedfrom theirrespectiveores ?
Answer» Solution :(i) Iron is pronetocorrosionbyrustingwhenexposedto air andmoisture. Therefore,toprotect itfromrusting, ironwindows/doorshavetobe paintedperiodecally.Inconstrast,whenexposedto air andmoisture,aluminiumformsan impervious coatof` Al_2O_3 `whichprotectsthe metalfrom furthercorrosion. Besides this,aluminiumframesandpanelslookmoredecorativethan THOSEOF ironandalsopaintingisnotrequired. (II) Theprincipleore ofironishaematite` (Fe_2O_3) `whilethat ofaluminium isbauxite` (Al_2O_3)`. (III) Ironisobtainedbyreductionofpurified` Fe_2O_3 `with coke inablastfurnace butaluminiumbeingmoreelectropositivethanironcannotbereducedbycoketo aluminiummetalbutinsteaditformsaluminiumcarbide `2Al_2O_3(s) + 9C (s) overset ("Heat") to Al_4C_3(s) +6CO (g) ` Therefore,AL isobtained by electroysis offusedpurified` Al _2 O _3`towhichcryolite` (Na_3AlF_6) ` and fluorspar`(CaF_2) `havebeen addedtomakealuminaagoodconductorofelectricityandalsotoreducethemeltingpointofthe MIX.