« previous next »
Pages: 1 ... 4 5 [6] 7 8 ... 56   Go Down

Author Topic: Chemistry Help HERE ONLY !!  (Read 107273 times)

Offline hummer618

  • Newbie
  • *
  • Posts: 33
  • Reputation: -1
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
Logged

Offline twilight

  • SF Senior Citizen
  • *****
  • Posts: 681
  • Reputation: 55
  • Gender: Female
  • wut u r in life depends on wut u choose..
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
Logged
Words and hearts should be handled with care
For words mis-spoken and hearts when broken are the hardest things to repair

Offline godfather93

  • SF Senior Citizen
  • *****
  • Posts: 720
  • Reputation: 799
  • Gender: Male
  • Tomorrow is a day that changes everyday
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.
Logged

Offline cockyxrocker

  • Newbie
  • *
  • Posts: 32
  • Reputation: 7
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
Logged

nid404

  • Guest
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
Logged

Offline Shogun

  • SF Geek
  • ****
  • Posts: 495
  • Reputation: 25
  • Gender: Male
  • the heavens cry within the arrival of the best
Re: Chemistry Help HERE ONLY !!
« Reply #80 on: May 26, 2009, 09:16:35 am »
By the way,all amphotric dissolves
Logged
one who masters both the pen and paper is indeed a true warrior.

\m/metal head\m/

Offline Naruto

  • SF Citizen
  • ***
  • Posts: 203
  • Reputation: 19
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.
Logged

Offline Bessy

  • Newbie
  • *
  • Posts: 29
  • Reputation: 7
  • Gender: Female
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.
Logged

Offline annie_angel

  • i m not an artist; just a painter...[ths is so random]
  • SF Geek
  • ****
  • Posts: 475
  • Reputation: 352
  • Gender: Female
  • --->>>Time is nothing but a Precious Enemy<<<---
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
Logged
Dont tell God how BIG your storm is...;tell your storm how BIG your GOD is.^_^

Offline Shogun

  • SF Geek
  • ****
  • Posts: 495
  • Reputation: 25
  • Gender: Male
  • the heavens cry within the arrival of the best
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
Logged
one who masters both the pen and paper is indeed a true warrior.

\m/metal head\m/

Offline gonnagetana

  • Newbie
  • *
  • Posts: 21
  • Reputation: -1
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!!!!
Logged

Offline Shogun

  • SF Geek
  • ****
  • Posts: 495
  • Reputation: 25
  • Gender: Male
  • the heavens cry within the arrival of the best
Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #86 on: May 26, 2009, 05:13:22 pm »
usually turns yellow i think
Logged
one who masters both the pen and paper is indeed a true warrior.

\m/metal head\m/

Offline lana

  • SF Immigrant
  • **
  • Posts: 112
  • Reputation: 916
  • Gender: Female
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 :)
Logged
''To be yourself in a world that is constantly trying to make you something else is the greatest accomplishment.''

Offline sweetsh

  • Retired Adminstrator
  • SF V.I.P
  • ********
  • Posts: 7049
  • Reputation: 65535
  • Gender: Female
  • *Freedom
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
Logged

Offline lana

  • SF Immigrant
  • **
  • Posts: 112
  • Reputation: 916
  • Gender: Female
Re: Chemistry Help HERE ONLY !!
« Reply #89 on: May 26, 2009, 05:39:33 pm »
and from were did we get the 25 ?
Logged
''To be yourself in a world that is constantly trying to make you something else is the greatest accomplishment.''
Pages: 1 ... 4 5 [6] 7 8 ... 56   Go Up
« previous next »