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Author Topic: Chemistry Help HERE ONLY !!  (Read 107540 times)

Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #435 on: May 30, 2009, 12:56:11 pm »
Quote from: thukon on May 30, 2009, 12:53:22 pm
Quote from: LilWayne on May 30, 2009, 12:45:53 pm
Quote from: 12345abc on May 30, 2009, 12:37:07 pm
here's some problems i had:
1.how do we write overall equations,e.g for habers process?
2. rust prevention-the mechanisms
3.why is a crucible in which magnesium oxide is being made covered with a lid?
4.colour of flame when there is incomplete combustion?
5.what reacts at room temp. with ethanol and ethanoic acid?
 A. CaCO3     B.CuO     C.CH3OH     D.Na
6.what are synthetic macromolecules?


please help!!! ???

1) i dont understand wat u mean!!
2)to prevent rust u could, paint the object, greasing or oiling, plastic coating, chromium plating, galvanizing with zinc, using stainless steel (which is corrosion resistant)
3)depends on the process if ur heating molten or aqueous substances then to prevent the splashing out of materials
4)orange = complete.. blue= incomplete
5) C), i think, cuz its the only organic substance  ( ASK SOMEONE ELSE CUZ IM NOT SURE!!)
6)these are man-made polyamide and polyester eg. nylon and terylene

Lil wayne, uve got the flames mixed up. Blue is complete. Red or orange is incomplete.
The answer is not C for the other thing. I m sure, because C is methanol. Im pretty sure methanol and ethanol dont react at room temp, but i dont know the answer.

ohh yeah i just realized, if its not methanol, could it be CuO , cuz it can oxidise ethanol into ethanoic acid, right?
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #436 on: May 30, 2009, 12:57:01 pm »
Quote from: zara on May 30, 2009, 12:55:03 pm
wait a min...
twilight said that red/orange in case of incomplete combustion....
lilwayne says:orange for complete combustion..

so now whch one is correct??

im mistaken zara
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #437 on: May 30, 2009, 01:03:16 pm »
Quote from: 12345abc on May 30, 2009, 12:37:07 pm
here's some problems i had:
1.how do we write overall equations,e.g for habers process?
2. rust prevention-the mechanisms
3.why is a crucible in which magnesium oxide is being made covered with a lid?
4.colour of flame when there is incomplete combustion?
5.what reacts at room temp. with ethanol and ethanoic acid?
 A. CaCO3     B.CuO     C.CH3OH     D.Na
6.what are synthetic macromolecules?


please help!!! ???
1.N2(g) + 3H2(g)  2NH3(g).
2.painting,galvanising,sacrificial protection, coating with plastic,using oil or grease
3.stops smoke from escaping
4.as twilight rightly said
5. with ethanol- D
with ethanoic acid-A,B,C and D
6.synthetic polymers- nylon,terylene and the like
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zara

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Re: Chemistry Help HERE ONLY !!
« Reply #438 on: May 30, 2009, 01:05:08 pm »
its Na whch reacts with ethanol and ethanoic acid at room temperature...
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #439 on: May 30, 2009, 01:06:54 pm »
Quote from: zara on May 30, 2009, 01:05:08 pm
its Na whch reacts with ethanol and ethanoic acid at room temperature...

oh so it asks which 1 reacts with both.....yeah so then Na
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Offline AN10

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Re: Chemistry Help HERE ONLY !!
« Reply #440 on: May 30, 2009, 01:08:25 pm »
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??
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Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #441 on: May 30, 2009, 01:10:11 pm »
Quote from: AN10 on May 30, 2009, 01:08:25 pm
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??

because thats what the scientists found out when they did tests on them, lol
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Offline thukon

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Re: Chemistry Help HERE ONLY !!
« Reply #442 on: May 30, 2009, 01:12:54 pm »
Quote from: AN10 on May 30, 2009, 01:08:25 pm
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??
Yeah lilwaynes right. Its one of those unexplainable things youd probably only learn why in college.

@nid. What do sodium and ethanol form when reacted? And sodium and ethanoic acid?
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Offline thukon

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Re: Chemistry Help HERE ONLY !!
« Reply #443 on: May 30, 2009, 01:22:07 pm »
@nid. U said ethanoic acid reacts with all 4. What do they form? Are they all addition reactions?
Im going afk. Sorry.
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Offline AN10

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Re: Chemistry Help HERE ONLY !!
« Reply #444 on: May 30, 2009, 01:23:07 pm »
Quote from: LilWayne on May 30, 2009, 01:10:11 pm
Quote from: AN10 on May 30, 2009, 01:08:25 pm
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??

because thats what the scientists found out when they did tests on them, lol
LoL..!!
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #445 on: May 30, 2009, 01:23:36 pm »
Quote from: thukon on May 30, 2009, 01:12:54 pm
Quote from: AN10 on May 30, 2009, 01:08:25 pm
why the melting point of alkali metals decreases down the group but of the halogens it increases down the group??
Yeah lilwaynes right. Its one of those unexplainable things youd probably only learn why in college.

@nid. What do sodium and ethanol form when reacted? And sodium and ethanoic acid?

with ethanol u get sodium ethoxide (CH3CH2ONa but we don't have alkoxides in our syllabus)and hydrogen is liberated

sodium ethanoate and hydrogen with ethanoic acid
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Offline thukon

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Re: Chemistry Help HERE ONLY !!
« Reply #446 on: May 30, 2009, 01:26:13 pm »
OMG ALKOXIDE?? IM GONNA DIE NOW. but whatever as long as its not in our syllabus. I figured out the sodium ethanoate while waiting for a response, but what about the other 3? U said it reacts with A B C and D.
AFK for real now bye.
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Offline crypsAnity

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Re: Chemistry Help HERE ONLY !!
« Reply #447 on: May 30, 2009, 01:40:46 pm »
Okay,, I am sort of confused .. umm.. do we have to know about the Faraday Constant and all for Chemistry? as in ..in calculations in electolysis ..
because I sort of just checked the syllabus.. couldnt find anything in it .. but its in my book .. n well its a cambridge one =S ..and though i know there are loadsa stuff in it which aint in the syllabus but i our teacher still tells us to study stuff to be on the safe side.. but i honestly dont have time to study all tht.. so pleaseee anyone tell me if they are iN!
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #448 on: May 30, 2009, 01:45:51 pm »
Quote from: thukon on May 30, 2009, 01:26:13 pm
OMG ALKOXIDE?? IM GONNA DIE NOW. but whatever as long as its not in our syllabus. I figured out the sodium ethanoate while waiting for a response, but what about the other 3? U said it reacts with A B C and D.
AFK for real now bye.

with ethanoic acid

ethanol forms ethyl ethanoate
calcium carbonate forms calium ethanoate, carbon dioxide and water
copper oxide forms copper ethanoate and water

my speed's too slow....sorry for the delay

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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #449 on: May 30, 2009, 01:49:54 pm »
Quote from: crypsanity on May 30, 2009, 01:40:46 pm
Okay,, I am sort of confused .. umm.. do we have to know about the Faraday Constant and all for Chemistry? as in ..in calculations in electolysis ..
because I sort of just checked the syllabus.. couldnt find anything in it .. but its in my book .. n well its a cambridge one =S ..and though i know there are loadsa stuff in it which aint in the syllabus but i our teacher still tells us to study stuff to be on the safe side.. but i honestly dont have time to study all tht.. so pleaseee anyone tell me if they are iN!
not for chem but for physics.......so chill 8)
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