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Author Topic: ALL CIE CHEMISTRY DOUBTS HERE !!  (Read 122936 times)

Offline HUSH1994

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #420 on: April 14, 2011, 08:23:44 am »
Good Luck :)
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Offline Master_Key

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #421 on: April 14, 2011, 08:53:27 am »
I need notes on REACTIONS OF ALDEHYDES AND REACTION MECHANISM OF ALDEHYDES. Can anyone pls help?
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Offline Aadeez || Zafar

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #422 on: April 14, 2011, 10:43:01 am »
ya i would give u in school,

in fact the reaction mechanism of all the organic reaction categorised by functional group
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Offline red_911

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #423 on: April 14, 2011, 02:42:30 pm »
•   Helium has the highest first ionisation energy why not hydrogen ? ???
cause it has only one electron
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Offline Arthur Bon Zavi

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #424 on: April 14, 2011, 02:45:45 pm »
Quote from: red_911 on April 14, 2011, 02:42:30 pm
•   Helium has the highest first ionisation energy why not hydrogen ? ???
cause it has only one electron

It is a noble/inert gas. Does not react and easily form ion.

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Offline Master_Key

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #425 on: April 14, 2011, 03:14:17 pm »
Quote from: red_911 on April 14, 2011, 02:42:30 pm
•   Helium has the highest first ionisation energy why not hydrogen ? ???
cause it has only one electron

Ionization energies increase from left to right. This is a trend in periodic table.
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Offline xlane

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #426 on: April 14, 2011, 10:41:41 pm »
how to find the oxidation state of  the element in the hydride n chloride ?? h2S , SCl2....
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Offline Vin

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #427 on: April 14, 2011, 10:52:46 pm »
Quote from: xlane on April 14, 2011, 10:41:41 pm
how to find the oxidation state of  the element in the hydride n chloride ?? h2S , SCl2....

You know the oxi. state of hydrogen, i,e +1
Take oxi. state of S = x

so,

2 x (+1) + x = 0
x = -2

as oxi. state of all compounds = 0

Do the same for the other compound. Oxi. state of Cl = -1.
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Offline HUSH1994

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #428 on: April 15, 2011, 05:44:11 am »
ON 2008 Q2,i tried it many times but its always wrong,can anyone help please?
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #429 on: April 15, 2011, 06:03:20 am »
Quote from: ~~!$!HUSH!$!~~ on April 15, 2011, 05:44:11 am
ON 2008 Q2,i tried it many times but its always wrong,can anyone help please?

Show me your workings.
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Offline HUSH1994

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #430 on: April 15, 2011, 06:05:32 am »
Thanks man,but no problem,i already solved it :)
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Offline Master_Key

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #431 on: April 15, 2011, 12:18:03 pm »
CIE Chemistry 9701 - O/N 2010

qp12

Question 22.

Please someone help and can you give me notes on reactions of aldehydes.
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #432 on: April 15, 2011, 12:46:16 pm »
Quote from: Master_Key on April 15, 2011, 12:18:03 pm
CIE Chemistry 9701 - O/N 2010

qp12

Question 22.

Please someone help and can you give me notes on reactions of aldehydes.

In the first scenario you will EVENTUALLY get a 2-hydroxy carboxylic compound. Think in terms of nucleophilic adittion of a CN- ion  and hence you should be able to determine the structure.

The second scenario is straight forward oxidation of an aldehyde to a carboxylic acid.
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Offline Master_Key

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #433 on: April 15, 2011, 02:17:58 pm »
Quote from: Ari Ben Canaan on April 15, 2011, 12:46:16 pm
In the first scenario you will EVENTUALLY get a 2-hydroxy carboxylic compound. Think in terms of nucleophilic adittion of a CN- ion  and hence you should be able to determine the structure.

The second scenario is straight forward oxidation of an aldehyde to a carboxylic acid.
Ari, I am getting the difference as 14. How could it be 16?

Can you plz explain.
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elemis

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Re: ALL CIE CHEMISTRY DOUBTS HERE !!
« Reply #434 on: April 15, 2011, 02:36:58 pm »
Quote from: Master_Key on April 15, 2011, 02:17:58 pm
Ari, I am getting the difference as 14. How could it be 16?

Can you plz explain.

When you react an ethanal with HCN you get 2-hydroxy propanenitrile. Hydrolysis of this gives you 2- hydroxypropanoic acid (RMM = 90)

Oxidation of propanal gives propanoic acid (RMM =74)

Do the subtraction....
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