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Author Topic: ALL CIE CHEMISTRY DOUBTS HERE !!  (Read 122930 times)

Offline $H00t!N& $t@r

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #345 on: January 25, 2011, 06:00:00 pm »
I'm having some trouble with calculating enthalpy change.
is the formula products - reactants or is it the other way round?  ???
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"If A equals success, then the formula is:
A=X+Y+Z, X is work. Y is play. Z is keep your mouth shut"- Albert Einstein

elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #346 on: January 25, 2011, 06:14:11 pm »
Quote from: $H00t!N& $t@r on January 25, 2011, 06:00:00 pm
I'm having some trouble with calculating enthalpy change.
is the formula products - reactants or is it the other way round?  ???


Enthalpy change of reaction = reactants - products
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Offline $H00t!N& $t@r

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #347 on: January 25, 2011, 06:27:34 pm »
pls check this website... im getting confused beacuse of this
http://www.science.uwaterloo.ca/~cchieh/cact/c120/heatreac.html
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"If A equals success, then the formula is:
A=X+Y+Z, X is work. Y is play. Z is keep your mouth shut"- Albert Einstein

elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #348 on: January 26, 2011, 02:38:16 am »
Quote from: $H00t!N& $t@r on January 25, 2011, 06:27:34 pm
pls check this website... im getting confused beacuse of this
http://www.science.uwaterloo.ca/~cchieh/cact/c120/heatreac.html

Enthalpy change of reaction and enthalpy change of formation are dfferent.
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Amelia

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #349 on: January 28, 2011, 07:14:19 pm »
Quote from: Sue T on January 25, 2011, 07:47:32 am
got it  ;) thank you - sorry 4 th trouble  :)

No problem. ;D

Quote from: thecandydoll on January 25, 2011, 02:35:26 pm
Heyy!
I need resources and help in Chemistry P5  Got no idea.No IDEA how to attempt this paper.

Practise Past Papers.

Here are some tips - http://answers.yahoo.com/question/index?qid=20081211153457AAmQNJl
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #350 on: February 04, 2011, 11:00:59 am »
Questions 23,26,29 and 30



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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #351 on: February 04, 2011, 12:57:52 pm »
Anyone ?
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #352 on: February 04, 2011, 01:38:40 pm »
QUestion 9

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Offline Amii

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #353 on: February 04, 2011, 02:04:38 pm »
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #354 on: February 04, 2011, 02:20:52 pm »
Quote from: Amii on February 04, 2011, 02:04:38 pm
C lowest activation energy

Stupid me.

And the rest, please ?
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Offline Amii

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #355 on: February 04, 2011, 02:22:07 pm »
Quote from: Ari Ben Canaan on February 04, 2011, 11:00:59 am
Questions 23,26,29 and 30
Not AT ALL sure

30) B - Butan-2-ol
On hydration can form But-1-ene,trans-but-2-ene and cis-but-2-ene (3 alkenes)

Butan-1-ol will form only But-1-ene(1 alkene)

2-methylpropan-1-ol and 2-methylpropan-2-ol will form 2-methylpropene (1 akene)I guess  :-\




  
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Offline Amii

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #356 on: February 04, 2011, 02:24:55 pm »
Quote from: Ari Ben Canaan on February 04, 2011, 02:20:52 pm
Stupid me.

And the rest, please ?
I don't take CIE. I called my tuition teacher but she was busy.

So if possible I wil check those rest questions with her later.
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #357 on: February 04, 2011, 05:17:26 pm »
For question 3 (a) (ii) why is it +22 KJ/mol ??

Shouldnt it be 410*4 +151 + (-299-3*410-299) ??

There are 4 C-H bonds broken but the MS pretends only one is broken.


 
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Amelia

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #358 on: February 04, 2011, 05:32:53 pm »
^ It's not pretending.

CH4 + I2 --> CH3I + HI

Only one C-H bond is broken to form H-I.

The rest are still intact -> CH3I
« Last Edit: February 04, 2011, 09:14:40 pm by Hamlet »
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #359 on: February 05, 2011, 11:45:44 am »
I've identified the chiral centres by drawing a red square next to them.

Am I correct ?
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