chemistry

Subject: chemistry Fri Mar 13, 2009 7:17 pm

hey guys how r ur revision goin......

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haven't started yet.. lol!

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me too!!

will start tmrw...or today at night, if i am not sleepy!! Very Happy

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hey plss tel...wat to do in the analyticsl chem n prac chem part??

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if such a chapter is in your text book, just go through it...and, my teachr told to see the practical chemistry of nineth too...they will ask such things in sect 1 only! tricky ones! if u have the observation book, go through it...

in that metallurgy, there is a big table in my tb about the common ores...

do u know common ores of which elements should be learnt..i.e. the name and the chemical compound!!

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wait..u hav dalal rite??

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no..goyal

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cn u guys plzz tell me wt 2 stdy in metellurgy

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apurva..me too asking the same!! the syll says only aluminium ore in detail and examples of ore and alloys of iron n zinc, but my maam has taught everything!!

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even im confused is there any1 2 say wht 2 study? Question

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even I am confused in metallurgy.......ne1 pls tell wat to study in that........nd wat not.....

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well vry frankly speakiin ill b doin metellurgy only for section a

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yes, our sir is a board examiner. i ll try to post

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thnx deboshree
but make it fast

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deboshree be fast as possible we r waiting 4 ur reply!!!!!!!!!!!

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my sir said.... common ores for iron, aluminium,and zinc.. we shd know.. and uses of them tooo...and he said... for iron.. the uses like railing is needed and for zinc .. tht galvanising property !!!!

hope u got.... wat u guyz neeeded ! Very Happy

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here it is: zinc
CRUSHING AND GRINDING OF ORE TO PROVIDE LARGE SURFACE AREA FOR MAXIMUM REACTION OF REAGENTS

CONCENTRATION OF ORE:IF IT IS ZnS THEN FROTH FLOTATION .IF IT IS ZnCO3 THEN HYDRAULIC WASHING

ROASTING: ZnS: VOLATILE IMPURITIES ARE NOT PRESENT IN THEIR VOLATILE STATE SO ROASTING IS DONE

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ZnS+O2=ZnO + SO2
TEMP IS NEARLY 900 DEGREE CELSIUS.
AT LOW TEMP. ZINC SULPHIDE GETS CONVERYTED TO ZINC SULPHATE WHICH CANNOT BE EASILY REDUCED AND MAKES THE COST HIGH.
AT HIGH TEMP. IF ZINC SULPHATE IS FORMED IT WILL DECOMPOSE TO ZINC OXIDE AND OXYGEN

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CALCINATION IS DONE FOR ZINC CARBONATE. TEMP IS LESS THAN 400 DEGREE CELSIUS
BCOZ AT HIGH TEMP. ZINC CARBONATE MELTS SO LESS TEMP. PREVENTS THIS AND ALSO HELPS IN ITS DECOMPOSITION TO ZINC OXIDE AND CARBON DIOXIDE

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THANXXX A LOT Deboshree...........that was of gr8 help..........
xactly wat I wanted to know.......nd BEST OF LUCK

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there is some more Boris:

REDUCTION OF ZINC OXIDE IS DONE BY REDUCING AGENT- COKE. REDUCTION BY COKE
IS SMELTING.ZINC OXIDE IS TAKEN IN A RETORT WHICH IS STUFFED WITH ZINC OXIDE
AND COKE.HEAT ENERGY IS PROVIDED BY PRODUCER GAS(CO+N2)AT 1400 DEGREE CELSIUS,
ZINC WILL BECOME VOLATILE AND CHANGE TO VAPOURS.THE CARBON MONOXIDE FORMED
(ZNO+C=ZN+CO) WILL REDUCE REMAINING ZINC OXIDE TO ZINC.FROM THE RETORT VAPOURS
OF ZINC, CO. CO2 ARE EVOLVED, ALL THESE REACH THE CONDENSER AND CO2 BEING AN
OXIDISING AGENT CAN CHANGE ZINC TO ITS OXIDE SO WE TAKE MOLTEN LEAD TO ABSORB
ZINC VAPOURS TO AVOID ITS OXIDATION.ZINC OBTAINED IS IMPURE AND IS CALLED ZINC
SPELTER.THIS IS 97.75% PURE WE NEED TO REFINE ZINC. MAJOR IMPURITIES ARE:
CADMIUM- BOILING PT.(B.P.) IS 767 DEGREE CELSIUS, Pb-1600 DEGREE CELSIUS ,Fe –
3000 DEGREE CELSIUS. REFINING IS DONE BY DISTILLATION. FOR FIRST
DISTILLATION,TEMP.IS 1000 DEGREE CELSIUS SO CADMIUM AND ZINC(920 DEGREE
CELSIUS) ARE DISTILLED OUT THEN THESE TWO SUBSTANCES ARE TAKEN FOR
DISTILLATION.THEN TEMP. IS 800 DEGREE CELSIUS AT WHICH CADMIUM IS DISTILLED OUT AND 99.99%PURE ZINC
IS OBTAINED.WE CAN ALSO ELECTRICALLY REFINE ZINC. IN THIS TAKE IMPURE ZINC
METAL AS ANODE,PURE ZINC METAL IS CATHODE,ZINC SALT HAVING LEAST DISCHARGING
PROPERTY-ZINC SULPHATE.

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i ll post the iron metallurgy tomorrow. Be patient with me.Sorry

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Thanks a lot again deboshree.........nd no need to be sorry......u did a gr8 work.......waitin for posts abt iron.........

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but hey....extraction of zinc not in sylabus

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ya anu ur right even i 2 wanted 2 say the same