Author Topic: Chemistry Help HERE ONLY !!  (Read 106252 times)

Offline aquarian93

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #375 on: May 30, 2009, 08:39:44 am »
omg, i ws hoping we dnt hav to :(
yes its annoying cuz its jus too much of memorizing :(
*sigh*

Offline aquarian93

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Re: Chemistry Help HERE ONLY !!
« Reply #376 on: May 30, 2009, 08:40:54 am »
so we hav to memorize da percentages and stuff? :(
i was hoping we don hav to :(

Offline SGVaibhav

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Re: MOLES
« Reply #377 on: May 30, 2009, 08:57:47 am »
please ask this in the chemistry thread.

Offline SGVaibhav

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #378 on: May 30, 2009, 08:58:35 am »
im not locking this thread, but please ask in the chemistry thread.

Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #379 on: May 30, 2009, 09:03:03 am »
so we hav to memorize da percentages and stuff? :(
i was hoping we don hav to :(

tht, yup ithink u gotta learn the percentage of substance contained in different type and steal

the property of so2 which helps is bleaching is paper making. now aquarian the explaination u recieved for this was how it helps, but in many past papers it says y this property is importanat , u gotta right cuz it helps in making paper. but if they say why its used to make paper, then the answer would be the explaination of AN10
one who masters both the pen and paper is indeed a true warrior.

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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #380 on: May 30, 2009, 09:12:13 am »
hey guys,

as the chemsitry exam is on the 1st of june, u must all be revising, and u MUST have some questions,

so if u have any CHEMISTRY questions, post them here and hopefully some one will help.

Gd Luck  :)



Hey Q80BOY
can u plz explain me extraction of aluminium ???


hey. extraction of aluminium works like this:
1)MOLTEN bauxite (aluminium oxide) is added to the vessel as an electrolyte.
2)sodium hydroxide is added to remove impurities like iron(II)oxides and sand.
3)since the boiling point of aluminium oxide is 2000oC, this will waste gr8 amount of energy. so to avoid this, cryolite is added to reduce its boiling point to 900oC.
4)then elctrolysis takes place, where aluminium becomes the cation and goes towards the cathode and settels at the bottom (as it is more dense) where it is extracted from.
5)the hot oxygen gas becomes an anion, rises towards the anode. Now the anode and cathode is made out f graphite(carbon), so the hot oxygen at the anode reacts with the carbon made anode to form carbon dioxide and eventually wear off. so then the anode shoul eventually be replaced.

well thts all, hope u understand, now they may ask u y carbon cannot be used to displace the oxygen from aluminium oxide to get aluminium. the answer,it wont happen, cuz carbon is more reactive than auminium(refer the reactivity series)

anything else u nedd just ask me ;D
« Last Edit: May 30, 2009, 09:16:43 am by Shogun »
one who masters both the pen and paper is indeed a true warrior.

\m/metal head\m/

Offline X Abdulrahman X

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Re: Chemistry Help HERE ONLY !!
« Reply #381 on: May 30, 2009, 09:15:22 am »
very nice explaination, + rep :]
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #382 on: May 30, 2009, 09:18:06 am »
Thanks, i made a mistake where i wrote tht aluminiuim settles at the bottom cuz it is "less dense" it should ve been "more dense" but dnt worry i modified it, (just to infrom)
one who masters both the pen and paper is indeed a true warrior.

\m/metal head\m/

zara

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Re: Chemistry Help HERE ONLY !!
« Reply #383 on: May 30, 2009, 09:35:06 am »
im reallii confused in naming the alcohols...cn summon tll me plz.. ???
i need an explanation..
Thanks..

Offline Tutu_93

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Re: Chemistry Help HERE ONLY !!
« Reply #384 on: May 30, 2009, 10:32:04 am »
I have a dought in may june 2008 ( second variant) q 4 ii in balancing
I worked it out and i got this Li2O+ H2so4 = Li2SO4+ H2O
But in the marking scheme it is Li2O + H2SO4  Li2SO4 + 2H2O  ?? can i knw y ??? ???

zara

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Re: Chemistry Help HERE ONLY !!
« Reply #385 on: May 30, 2009, 10:35:18 am »
okay...so now where did all the chemistry geniuses went??

n y did my rep go down??

Offline saifalan

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Re: MOLES
« Reply #386 on: May 30, 2009, 10:37:07 am »
Sgv merge it with any Chem topics. I wuld have done it myself but dont knw which to merge it with.
Why so seroisee ??

Offline aquarian93

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Re: Chemistry Help HERE ONLY !!
« Reply #387 on: May 30, 2009, 10:37:48 am »
im reallii confused in naming the alcohols...cn summon tll me plz.. ???
i need an explanation..
Thanks..

OH is the functional group, so all alcohols need hav the "OH" in their symbol.

the first one is CH3OH - Methanol (which can make u blind)
the second one is C2H5OH - Ethanol
the third on is C3H7OH - Propanol
the fourth one is C4H9OH - Butanol
the fifth one is C5H11OH - Pentanol
the sixth one is C6H13OH - Hexanol

and so on


zara

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Re: Chemistry Help HERE ONLY !!
« Reply #388 on: May 30, 2009, 10:42:26 am »
no i didnt mean this...
i meant to ask about the naming of the isomers of alcohols???
how to do that...
like for alkenes isomers we 1st chk where the double bond comes n gets the lowest number and then depending on it the alkyl group is numbered..

so how to do this naming for the isomers of alcohols???

plz help..

Offline SGVaibhav

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Re: MOLES
« Reply #389 on: May 30, 2009, 10:49:47 am »
hmm i have never tried.
so i am scared, what if i do some huge error.
it has to be merged with the thread "Chemistry Help HERE ONLY !!"