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Offline Ghost Of Highbury

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chemistry doubt~
« on: November 10, 2009, 06:01:40 am »
N2 + 3H2 --> 2NH3         /_\H = –92 kJ/mol

(a) On the same axes draw energy profile diagrams to show both the catalysed and the
uncatalysed reaction. Label the diagram to show
• the catalysed and uncatalysed reactions,
• the reactants and products,
• the enthalpy change for the reaction.

what are energy profile diagrams??

can anyone plz draw and attach it here. THANKS A LOT!
« Last Edit: November 10, 2009, 06:19:10 am by A@di »
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Offline @d!_†oX!©

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Re: chemistry doubt~
« Reply #1 on: November 10, 2009, 06:34:22 am »
dude...energy profile diagram is when u show the energies of the reactants and their products once thay have reacted....You will have an idea of whit it look like from the diagram below....u must have doen it in class...
now all u gotta do to this diagram is...
just replace "REACTANTS" from the diagram with "N2 + 3H2"
and "PRODUCTS" with "2NH3"
the label for the catalysed and uncatalysed reactions are already there...
and i dont think u need to know the exact enthalpy change for these reactions at IG'z

tell me if u still need an EXACT diagram for this...
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Offline Ghost Of Highbury

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Re: chemistry doubt~
« Reply #2 on: November 10, 2009, 06:41:33 am »
SOMETHING LIKE THIS? if so, where do i label the catalysed and uncatylsed reactions? do i have to make another set?
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Offline @d!_†oX!©

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Re: chemistry doubt~
« Reply #3 on: November 10, 2009, 06:44:15 am »
sorry dude...i forgot to attach the file...nd not that way...cuz u show reactants having more energy tan products at the start...which isn't true...they have more energy but it first increases till the activation energy nd then decreases to the energy of products...see this nd tell me if u got it now...
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Offline @d!_†oX!©

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Re: chemistry doubt~
« Reply #4 on: November 10, 2009, 06:45:11 am »
u have to show that rise in energy cuz otherwise u cannot differentiate btwn a catalysed reaction and uncatalysed reaction
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Offline Ghost Of Highbury

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Re: chemistry doubt~
« Reply #5 on: November 10, 2009, 06:49:28 am »
the catalyst helps break the bonds, is this the reason y less activation energy is required?
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Offline @d!_†oX!©

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Re: chemistry doubt~
« Reply #6 on: November 10, 2009, 06:51:35 am »
no the catalyst provide a mutual surface for the gases to react i this reaction...so they come closer nd collide more frequently...so as a result their activation energy is reduced....
this is why the catlyst makes a reaction go faster cuz it reduces the activation energy of the reaction and thus provides a short-cut..
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Offline dlehddud

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Re: chemistry doubt~
« Reply #7 on: November 10, 2009, 09:41:55 am »
hey guys
for 2006 chem ppr 3 mj,
question4 d)
i'm quite positive the answers Ge2H8..
bt the ms says Ge2H6..
i thought valency for germanium was 4+? y wuld it end up wid 6 hydrogens per 2 germaniums?
dat wuld mean germanium has a valency of 3+!!
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Offline @d!_†oX!©

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Re: chemistry doubt~
« Reply #8 on: November 10, 2009, 09:47:14 am »
dude even i thought Ge2H8 for the answer applying the same concept as u did...
but if u read the question again....it says saturated hydrides of carbon are called alkanes...
nd then it asks us to write the formula for the hydride of germanium...
so for this...we'll apply the same general molecular formula of alkanes and thus the answer will be Ge2H6
tell me if u still don't get it...
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Offline dlehddud

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Re: chemistry doubt~
« Reply #9 on: November 10, 2009, 10:11:27 am »
wait.. then wat is the exact defintion of hydrides?
nd doesn't the alkane formula only work for ALKANES? it's the general formula for members of the alkane homologous series isn't it?
y wuld it apply for a covalent structure?
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Offline dlehddud

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Re: chemistry doubt~
« Reply #10 on: November 10, 2009, 10:21:23 am »
NNOOOO!! I got it!  ;D ;D
lol adi toxic  u shuldnt think so complicated ><
think about it! they are both nonmetals with positive valences, so they wuld form a covalent bond with each other rite?
think if it was Ge2H8, we're saying we have TWO GeH4.. but if the whole COMPOUND has to have 2 Ge atoms, then every atom has to be bonded with each other rite?
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Offline @d!_†oX!©

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Re: chemistry doubt~
« Reply #11 on: November 10, 2009, 10:22:56 am »
wait dude...if u don't understand the above thing...i'll give u another explnation...this one's easier to comprehend
see...u are thinking of Ge having a velency of 4
so a compound wid one Ge shud be GeH4
nd yes u are right at that
but when there are 2 Ge
then??
see the diagram
shudn't it be like this??
yes it has to be...
so now u know that a compound wid 2 Ge will have this structure which shows Ge2H6

now can u see the link...it is following the GMF of alkanes

the reason is because alkanes are single bond compounds of carbon and hydrogen and here only carbon has been replaced by Germanium

do u get it now dude??
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Offline dlehddud

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Re: chemistry doubt~
« Reply #12 on: November 10, 2009, 10:28:01 am »
Quote from: @d!_†oX!© on November 10, 2009, 10:22:56 am
wait dude...if u don't understand the above thing...i'll give u another explnation...this one's easier to comprehend
see...u are thinking of Ge having a velency of 4
so a compound wid one Ge shud be GeH4
nd yes u are right at that
but when there are 2 Ge
then??
see the diagram
shudn't it be like this??
yes it has to be...
so now u know that a compound wid 2 Ge will have this structure which shows Ge2H6

now can u see the link...it is following the GMF of alkanes

the reason is because alkanes are single bond compounds of carbon and hydrogen and here only carbon has been replaced by Germanium

do u get it now dude??


o rite!! cos germanium and carbon have the same valency there like the same element? yu just have to replace them rite? lol
i get it now
nd dats wot i was saying! about the diagram, just replace the lines with x and o's nd yu get a covalent diagram!
altho there was no way i was going to think that up in the exam lol
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Offline @d!_†oX!©

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Re: chemistry doubt~
« Reply #13 on: November 10, 2009, 10:30:02 am »
glad that u got it....
nd yeah :P even i wudn't think so much in an examination  hall...
get some more doubts if u have any
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