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Author Topic: Chemistry Help HERE ONLY !!  (Read 106026 times)

Offline hummer618

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #75 on: May 25, 2009, 09:48:11 pm »
guys there is a rumour, saying that there will be no


- Organinc chemistry,
- Reactivity Series
- moles
-Endo or Exo thermic thingys

however will be

Rates of Reactions,
Bonding
and da rest


ur welcome


i am soo bloody confident
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Offline twilight

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Re: Chemistry Help HERE ONLY !!
« Reply #76 on: May 25, 2009, 09:51:40 pm »
u will b knowing the total oxidation state of the compound ...
if its a compound .. then the oxidation state is zero
if its an ion then the oxidation state is the final charge on that ion

now suppose we take KMnO4  .. the final oxidation sate is zero .. because there is no overall charge on the compound
suppose u wanna get the oxidation number of Mn .. assume it to be x
we know that K is +1 , and O is -2 ....    this is how u do it
   (+1) + x + (-2)(4)  = 0
solve algebrically so x = 7
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Offline godfather93

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Re: Chemistry Help HERE ONLY !!
« Reply #77 on: May 25, 2009, 10:01:37 pm »
Quote from: twilight on May 25, 2009, 09:51:40 pm
u will b knowing the total oxidation state of the compound ...
if its a compound .. then the oxidation state is zero
if its an ion then the oxidation state is the final charge on that ion

now suppose we take KMnO4  .. the final oxidation sate is zero .. because there is no overall charge on the compound
suppose u wanna get the oxidation number of Mn .. assume it to be x
we know that K is +1 , and O is -2 ....    this is how u do it
   (+1) + x + (-2)(4)  = 0
solve algebrically so x = 7
thank u so much 4 ur response. (+rep) i read the same method in one of the other sites and i understand very well now.
this is the site i used
http://www.chemguide.co.uk/inorganic/redox/oxidnstates.html

do u know what is the oxidation state? as in what is it meant to represent in an atom.
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Offline cockyxrocker

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Re: Chemistry Help HERE ONLY !!
« Reply #78 on: May 26, 2009, 07:13:10 am »
hey could anyone gimme the list of water soluble and insoluble gases
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #79 on: May 26, 2009, 08:35:51 am »
Quote from: cockyxrocker on May 26, 2009, 07:13:10 am
hey could anyone gimme the list of water soluble and insoluble gases

well common ones that dissolve are

Hydrogen chloride
Hydrogen sulphide
Ammonia
Oxygen
Carbon dioxide
Nitrogen dioxide
Chlorine gas
Carbon monoxide
nitrous oxide

Actually most gases dissolve in water but have different values of solubility. But those gases are complex so I think these should be enough for our syllabus

Ill try to get a full list if possible
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #80 on: May 26, 2009, 09:16:35 am »
By the way,all amphotric dissolves
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Offline Naruto

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #81 on: May 26, 2009, 12:29:47 pm »
@ Monica and Shogun
thank u guyz for your guidance +rep for both of you :)

@hummer618
well i havent heard about that kind of rumour before.... so sorry cant say anything. but i think that you should prepare for these topics.
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Offline Bessy

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #82 on: May 26, 2009, 03:09:18 pm »
 our teacher made a summary according to the syllabus.
 and i just review it +reading the organic part word by word before the mock exam
 and i get A   just a few marks more to get A *
 so if you know very well about syllabus and+ read some important chapter carefully
 u will succeed.
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Offline annie_angel

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #83 on: May 26, 2009, 03:29:04 pm »
Quote from: Monica on May 25, 2009, 06:12:54 pm
Quote from: Naruto on May 25, 2009, 06:09:07 pm
ahan true!! but i meant that which one is more improtant to study first for revision.

ok i guess:

1)Organic chemistry
2)Metals
3)Electrolysis
4)Rust prevention
5)Sulphur, Air, Water, Carbohydrates


I think.... all will come...but Metals is an important topic...

6) mole concept
7)redox reactions
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Offline Shogun

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #84 on: May 26, 2009, 04:15:23 pm »
Quote from: hummer618 on May 25, 2009, 09:48:11 pm
guys there is a rumour, saying that there will be no


- Organinc chemistry,
- Reactivity Series
- moles
-Endo or Exo thermic thingys

however will be

Rates of Reactions,
Bonding
and da rest


ur welcome


i am soo bloody confident


no way man the life of paper 3 runs on these thing, what im saying is tht without this, there really isnt any paper 3.
 Organinc chemistry,
- Reactivity Series
- moles
-Endo or Exo thermic thingys

these are always there in paper3 chemistry
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one who masters both the pen and paper is indeed a true warrior.

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Offline gonnagetana

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #85 on: May 26, 2009, 04:21:41 pm »
Hey, does anyone know what colour change occurs when potassium iodide is reduced??? Its in the syllabus, you gotta know this!!!!
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Offline Shogun

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #86 on: May 26, 2009, 05:13:22 pm »
usually turns yellow i think
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one who masters both the pen and paper is indeed a true warrior.

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Offline lana

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Re: Chemistry Help HERE ONLY !!
« Reply #87 on: May 26, 2009, 05:25:19 pm »
hi all ... i'v been stuck trying to solve this question since forever please somebody help it's in October\November 2001 question 3 a
Thanks aloot :)
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Offline sweetsh

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Re: Chemistry Help HERE ONLY !!
« Reply #88 on: May 26, 2009, 05:34:33 pm »
Okay here is it.
They are 5-25
Because for 3CO2 it was 15cm3
15/3 =5
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Offline lana

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Re: Chemistry Help HERE ONLY !!
« Reply #89 on: May 26, 2009, 05:39:33 pm »
and from were did we get the 25 ?
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