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Author Topic: Chemistry Help HERE ONLY !!  (Read 106012 times)

Offline Roza

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Re: Chemistry Help HERE ONLY !!
« Reply #45 on: May 25, 2009, 10:12:06 am »
Quote from: ManaH on May 25, 2009, 10:05:09 am
Quote from: Roza on May 25, 2009, 10:01:21 am
Quote from: ManaH on May 25, 2009, 08:39:12 am
I need help in chemistry  oct/nov 08 second varient paper
Q 7ai)
i actually got this question for my mocks

here's the working
volume of oxygen left
according to question             according to equation
1 mol                                         6.5 mol
if 20cm3                                           x??
so 20 x 6.5 = 130cm3

150-130 = 20cm3

so volume of oxygen left = 20cm3

volume of carbondioxide formed

1                       4
20                     x??
so 20 x 4 = 80

volume of carbondioxide formed = 80cm3
Thankyou but wont we use the formulaa???
n umm why did u subtracted it form 150?

no there is no need to use a formulae

n oxygen is in excess n we want to find the volume of oxygen left at the end of experiment
so 150-130= 20
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Offline MaNa

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Re: Chemistry Help HERE ONLY !!
« Reply #46 on: May 25, 2009, 10:14:33 am »
Quote from: Roza on May 25, 2009, 10:12:06 am
Quote from: ManaH on May 25, 2009, 10:05:09 am
Quote from: Roza on May 25, 2009, 10:01:21 am
Quote from: ManaH on May 25, 2009, 08:39:12 am
I need help in chemistry  oct/nov 08 second varient paper
Q 7ai)
i actually got this question for my mocks

here's the working
volume of oxygen left
according to question             according to equation
1 mol                                         6.5 mol
if 20cm3                                           x??
so 20 x 6.5 = 130cm3

150-130 = 20cm3

so volume of oxygen left = 20cm3

volume of carbondioxide formed

1                       4
20                     x??
so 20 x 4 = 80

volume of carbondioxide formed = 80cm3
Thankyou but wont we use the formulaa???
n umm why did u subtracted it form 150?

no there is no need to use a formulae

n oxygen is in excess n we want to find the volume of oxygen left at the end of experiment
so 150-130= 20
alright thankyou
+ rep for u ;D
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Offline Aishath

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Re: Chemistry Help HERE ONLY !!
« Reply #47 on: May 25, 2009, 12:12:33 pm »
hey everyone...
can someone explain to me titration briefly cos i am not really gud at topic..
Thanks
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #48 on: May 25, 2009, 12:21:02 pm »
Titration

An accurately measured volume of a solution is normally placed in a conical flask and the other in a burette. The solution from the burette is added slowly until the solution in the flask has completely been used up by the reaction. This is shown by the use of an indicator. The volume of the solution used can then be read off the burette scale.

This technique is most commonly used for acid-base reactions
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Offline Aishath

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Re: Chemistry Help HERE ONLY !!
« Reply #49 on: May 25, 2009, 12:25:28 pm »
thanks nid404!!!
great explanation!!! i understood it well....

+ rep for u! ;)
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Offline annie_angel

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Re: Chemistry Help HERE ONLY !!
« Reply #50 on: May 25, 2009, 12:28:10 pm »
wat are macromolecular structures and giant molecular stictures?i keep on 4getting these 2 all the tym...:(
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Offline hyebyekadal

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Re: Chemistry Help HERE ONLY !!
« Reply #51 on: May 25, 2009, 12:31:11 pm »
macromolecules diamonds  silica and germanium(i think about that not too sure)
giant molecular structures i think are just like giant molecules i guess
im not too sure myself!! i better go revise again myself!
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #52 on: May 25, 2009, 12:34:21 pm »
I believe both are the same-giant and macro

can u give me the exact question. w8 hybye said was right in a way. if your talking about giant covalent molecules then it's diamond, silica,graphite


germanium is an element so that is wrong
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Offline MaNa

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Re: Chemistry Help HERE ONLY !!
« Reply #53 on: May 25, 2009, 12:35:08 pm »
Quote from: annie_angel on May 25, 2009, 12:28:10 pm
wat are macromolecular structures and giant molecular stictures?i keep on 4getting these 2 all the tym...:(
MAcro molecules:they are giant covelant sturcures which have million of atoms held together by covelent bond
like diamond , siliconoxide(sand) , graphite etc
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Offline annie_angel

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Re: Chemistry Help HERE ONLY !!
« Reply #54 on: May 25, 2009, 12:36:59 pm »
Quote from: nid404 on May 25, 2009, 12:34:21 pm
I believe both are the same-giant and macro

can u give me the exact question. w8 hybye said was right in a way. if your talking about giant covalent molecules then it's diamond, silica,graphite


germanium is an element so that is wrong
its not a question...i just need da meanings... ;D
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Offline godfather93

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Re: Chemistry Help HERE ONLY !!
« Reply #55 on: May 25, 2009, 12:40:26 pm »
a giant molecule is called a macro molecule. hence, it is the same thing.
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Offline annie_angel

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Re: Chemistry Help HERE ONLY !!
« Reply #56 on: May 25, 2009, 12:42:25 pm »
really?cuz these two were writtn separately in one of my book...
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #57 on: May 25, 2009, 12:42:45 pm »
k here u go

According to my collins A-Z chemistry dictionary
 
A macromolecule is a term usually used for molecules with a relative molecular mass value greater than 1000, namely polymers such as carbohydrates and plastics, and molecules such as proteins and nucleic acids.
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Offline annie_angel

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Re: Chemistry Help HERE ONLY !!
« Reply #58 on: May 25, 2009, 12:44:34 pm »
thank u all!!atleast they turned out to be easier now...:D...+rep
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Offline afarooq

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Re: Chemistry Help HERE ONLY !!
« Reply #59 on: May 25, 2009, 01:41:48 pm »
The Kinetic Theory explains the properties of solids, liquids and gases in terms of the
movement of particles.
Liquids and gases both take up the shape of the container but a gas always fills the
container. Explain this, using the ideas of the Kinetic Theory.


A question from the m/j 2002 paper, but i dont understand it, please help!
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