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Author Topic: ALL CIE CHEMISTRY DOUBTS HERE !!  (Read 110705 times)

Offline Master_Key

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #510 on: May 07, 2011, 07:31:10 am »
Quote from: EMO123 on May 06, 2011, 03:21:35 pm
master_key
2,4-dinitrophenaylhydrazine also reacts with ketones to give a deep yellpw pr orange precipitate

there fore
y is a aldehyde
so there is only one aldehyde not ketone also present in that combination

:. D is the right answer

hope i helped

There are no ketone groups in that question so i mentioned "Aldehyde".
2,4-dnph reacts with Carbonyl compounds.
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Offline EMO123

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #511 on: May 07, 2011, 10:31:24 am »
Quote from: Master_Key on May 07, 2011, 07:31:10 am
There are no ketone groups in that question so i mentioned "Aldehyde".
2,4-dnph reacts with Carbonyl compounds.
ya you are right but it was just for the reference
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Offline TJ-56

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #512 on: May 13, 2011, 05:09:53 pm »
How do we calculate the value of x in May June 2008 Paper 5 question 2 (f) ?
I plotted the mass of CuO on the y-axis against the mass of the basic carbonate on the x-axis. Now the 2 values to calculate the gradient are 5.70g (basic carbonate, x-axis) and 4.00g (CuO, y-axis). So how exactly do we use these numbers to calculate x ?
Appreciate any help.
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Offline thecandydoll

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #513 on: May 14, 2011, 07:42:59 am »
OCt/Nov 2010 PAPER 53
How do you fill in the table?
DO we need to find conc in solvent a and b?
If so how?
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Offline noor.h92

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #514 on: May 14, 2011, 12:23:48 pm »
Hi,

has anyone done the 2011 biology paper 3. (As-level). In question 1ai- where you have to draw a graph what would be my x-axis and y-axis?
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #515 on: May 14, 2011, 12:27:24 pm »
Quote from: noor.h92 on May 14, 2011, 12:23:48 pm
Hi,

has anyone done the 2011 biology paper 3. (As-level). In question 1ai- where you have to draw a graph what would be my x-axis and y-axis?

2011.... You from the future ?

Also, does this look like the CIE Biology thread ?
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Offline TJ-56

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #516 on: May 14, 2011, 01:42:34 pm »
Quote from: TJ-56 on May 13, 2011, 05:09:53 pm
How do we calculate the value of x in May June 2008 Paper 5 question 2 (f) ?
I plotted the mass of CuO on the y-axis against the mass of the basic carbonate on the x-axis. Now the 2 values to calculate the gradient are 5.70g (basic carbonate, x-axis) and 4.00g (CuO, y-axis). So how exactly do we use these numbers to calculate x ?
Appreciate any help.
Anyone?
I also have a question in the October November 2009 paper: question 1 (d) (table), I found it really confusing, and the ms didnt help a lot. Can someone explain?
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Offline Master_Key

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #517 on: May 14, 2011, 03:52:54 pm »
A short poem.

Ionic Bonding Poem - a snippet of chemical poetry

(anon Y11 student, Whitby Community College, Oct 31st 2002)

How do I long for a full outer shell!

being chlorine having seven, is a horrid hell

but my name is sodium and I have one spare!

I want to lose it, can we not share?

No? for are we not a perfect match

chuck it to me, I promise to catch

then we can live our separate ways

and live with full shells to the end of our days!

and so our tale comes to an end

as positive and negative we shall remain friends
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Offline HUSH1994

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #518 on: May 15, 2011, 06:59:19 am »
Nice one master key, +rep :)
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Offline EMO123

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #519 on: May 15, 2011, 07:04:41 am »
Quote from: Master_Key on May 14, 2011, 03:52:54 pm
A short poem.

Ionic Bonding Poem - a snippet of chemical poetry

(anon Y11 student, Whitby Community College, Oct 31st 2002)

How do I long for a full outer shell!

being chlorine having seven, is a horrid hell

but my name is sodium and I have one spare!

I want to lose it, can we not share?

No? for are we not a perfect match

chuck it to me, I promise to catch

then we can live our separate ways

and live with full shells to the end of our days!

and so our tale comes to an end

as positive and negative we shall remain friends
good poem man
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Offline Master_Key

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #520 on: May 15, 2011, 08:30:54 am »
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Offline EMO123

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #521 on: May 15, 2011, 10:02:40 am »
Quote
Esters are a useful group of compounds due to their distinctive smells. One example
of an ester is ethyl ethanoate, its formation is shown below.

CH3COOH(aq) + C2H5OH(aq)?CH3COO C2H5(aq)
+ H2O(l)

a) Systems like this are described as being a 'dynamic equilibrium'. Explain
the term 'dynamic equilibrium'

b) Write down the expression for the equilibrium constant, Kc, for this reaction.

c) Calculate the value of Kc for this reaction given the equilibrium concentrations below.

[CH3COOH] = 0.08 moldm-3

[C2H5OH] = 0.08 moldm-3

[CH3COO C2H5] = 0.25 moldm-3

[H2O] = 0.1 moldm-3

d) Concentrated sulphuric acid is added to the reaction mixture as it removes water molecules. What effect would this have on the equilibrium position of this system?
need the answer of D)
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Offline EMO123

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #522 on: May 15, 2011, 10:09:32 am »
Quote
2. The Haber-Bosch process is used for the large-scale production of ammonia from
nitrogen and hydrogen gas. The reaction is shown below:

N2(g) + 3H2(g)?2NH3(g)

a) Write an expression for Kp for this reaction.

b) What are the units of Kp for this reaction? (Assume pressure is measured in kPa)

c) When the temperature is raised for this process the proportion of NH3(g) in the mixture decreases. Explain this observation.

d) What effect will an increase in the total pressure have on the equilibrium position?
i have doubt in B)
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Offline aneeta

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #523 on: May 15, 2011, 12:33:26 pm »
OMG OMG!!! IM FREAKING OUT ABOUT PAPER 2 TOMORROW!! x_x ORGANIC IS KILLING ME!! ANY SUGGESTIONS?!
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Offline aldehyde1612

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #524 on: May 15, 2011, 01:50:46 pm »
Quote from: aneeta on May 15, 2011, 12:33:26 pm
OMG OMG!!! IM FREAKING OUT ABOUT PAPER 2 TOMORROW!! x_x ORGANIC IS KILLING ME!! ANY SUGGESTIONS?!
just relax.. and stop freaking out!
I suggest you dont study any chem for now... just quickly skim over your short notes and stuff if you havent done so already. THEN STOP. listen to music and take a walk .. or something, anything and STOP FREAKING OUT. You'll be fine. 

And if tomoro it gets too hectic.. just breaaathe.  ;D
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.We know a little about a lot of things; Just enough to make us dangerous.
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