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chem now........

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pavan
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PostSubject: chem now........ Fri Mar 13, 2009 10:57 pm

Can u guyz help me out.......plzzzzz
(!)Explain y dil.sulphuric acid is a strnger acid thn conc. sulphuric acid??????????? Mad Embarassed
(~)give one use of pottasium hydroxide...

shud we kno to calc the PH of solns???????(if conc . of it is givn) No No No
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PostSubject: Re: chem now........ Sat Mar 14, 2009 11:13 am

1) actually, the question should be wrong...coz, the strength of an acid does NOT depend upon its concentration...in my text, its given in a big box, that a strng acid will remain strng even if it is dilute .

or, since the question is asked, we have to answer! so, i think its because the mobility of the ions increases? Suspect i dunno!!

2) KOH is used in soap manufacture

3) no...PH is not in syll. just knw that, above 7 is alkali, below 7 is acid and 7 is neutral.

ALL the best!
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pavan
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PostSubject: Re: chem now........ Sat Mar 14, 2009 12:03 pm

may b anu.......but im stil in doubt Mad
anyway....ALL THE BEST FRTHE EXAMS
thnx for anss


vat s formalin?????give its use
give a use of carbon tetrachloride
vat si denaturated alchohl?????/


Last edited by pavan on Sat Mar 14, 2009 12:11 pm; edited 1 time in total (Reason for editing : to add some quests)
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Arya Nair
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PostSubject: Re: chem now........ Sat Mar 14, 2009 7:49 pm

thanks for the answers
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abhi_1993
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PostSubject: ans Sun Mar 15, 2009 12:33 am

i know im a total stranger...but i thought i shud help..
well...dil sulphuric acid is strongr than conc.H2SO4 bcoz pH of an acid is determined by the concentration of H3O+(hydronium) ions in solution....so...dil. H2SO4 will furnish more H30+ ions dan conc.H2SO4(bcoz of water)..and hence it will have a lower pH.....dats wy its stronger
we dont have formalin according 2 d scope of our syllabus(we dont hav aldehydes)...but anyway..its 40% HCHO in CH3OH...used as antiseptic, disinfectant,etc..
n use of carbon tetrachloride is dat its a solvent(for organic compounds ofcourse)


Last edited by abhi_1993 on Sun Mar 15, 2009 1:23 am; edited 1 time in total
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PostSubject: Re: chem now........ Sun Mar 15, 2009 12:44 am

i 4gt to mention..im not very sure ....but..denatured alcohol is ethyl alcohol made unfit 4 drinkin by adding methanol,CuSO4(gives it a blue colour) and pyridine(which stinks)...dey do that as it is used in industries n dey dont want ppl to drink it...so dey make it look strange(blue) n make it stink(by use of pyridine)!!
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Teju
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PostSubject: Re: chem now........ Sun Mar 15, 2009 1:33 am

tnxx anu n abhi 4 ur answers
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deboshree
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PostSubject: Re: chem now........ Sun Mar 15, 2009 8:28 am

oh abhi , denatured alcohol is absolutely correct. it is exactly -word by word same to what our sir has told
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pavan
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PostSubject: Re: chem now........ Sun Mar 15, 2009 11:11 am

thx abhi...
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Anirudh The Conquerer
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PostSubject: Re: chem now........ Sun Mar 15, 2009 12:15 pm

concentration of the acid depends on the no. of H+ ions.
concentrated acid contains less no. of water molecules which is a polar solvent so rate of dissociation of H+ ions is less but in a dilute acid more no. of water molecules so rate of dissociation of H+ is more thus it is more acidic than the concentrated H2SO4

what is gas carbon?Question
what is "Le Chatelier's principal"? Question
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PostSubject: Re: chem now........ Sun Mar 15, 2009 2:15 pm

hey anirudh , no. of H+ is the degree of ionization na....concentration is just the amount of water present in a given sample of a solution

still not convinced.....maybe we should write these answers only if they ask in the board...i hope they dont give it!
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PostSubject: Re: chem now........ Sun Mar 15, 2009 6:36 pm

uh...about H+ ions...actually i believe they cannot exist themselves as they react with water to give H3O+ions(ie. hydronium ions)...more the concentration of hydronium ions more acidic it is....
gas carbon is another form of carbon...dont need to know much about it...beyond our scope...just need to know that it is used
Le chatelier's principle...the details are beyond our scope...but it says that wen the reaction is exothermic, reaction is favoured by decreasing temperature and when the resulting volume is less than the reactants( eg. N2+3H2-->2NH3 dat means 4(3+1) vols of reactants give 2 vols of ammonia)..it is favoured by increase in pressure...the reason is a little complicated...its somthing about it opposing the system and counteracting the change...
but you cannot decrease the temp so much that it slows the reaction...so optimum temp is used...n high pressure may damage stuff...so optimum pressure is used accordingly....
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Midhun Sarath
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PostSubject: Re: chem now........ Sun Mar 15, 2009 9:13 pm

tnx abhi Very Happy
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Midhun Sarath
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PostSubject: Re: chem now........ Sun Mar 15, 2009 9:14 pm

ani.. ur 2nd doubt is out of syll ?
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abhi_1993
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PostSubject: Re: chem now........ Sun Mar 15, 2009 9:18 pm

no...the le chatelier's principle is in syllabus...but the details are not
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Hari
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PostSubject: Re: chem now........ Sun Mar 15, 2009 10:14 pm

le chatelier's priciple:::::: if a reaction is exothermic it is favoured by lowering the temrature(better yield)
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nikhita
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PostSubject: Re: chem now........ Sun Mar 15, 2009 10:23 pm

hey guys thanx 4 ur asnwers Smile
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Midhun Sarath
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PostSubject: Re: chem now........ Sun Mar 15, 2009 10:34 pm

tnx hari Very Happy
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Anirudh The Conquerer
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PostSubject: Re: chem now........ Mon Mar 16, 2009 10:11 am

thnx guys Very Happy Very Happy Very Happy Very Happy Very Happy Very Happy
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PostSubject: Re: chem now........ Mon Mar 16, 2009 10:13 am

thnx guys Very Happy Very Happy Very Happy Very Happy Very Happy Very Happy
all the best for ur exams
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