Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 268730 times)

Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1200 on: May 26, 2011, 03:25:16 pm »
why do we use acidifed potassium dichromate to oxidise ethanol?

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1201 on: May 26, 2011, 03:32:35 pm »
why do we use acidifed potassium dichromate to oxidise ethanol?

The Hydrogen ions from the acid aid the change of oxidation state of the Chromium which in turn enables oxidation.

Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1202 on: May 26, 2011, 03:42:07 pm »
The Hydrogen ions from the acid aid the change of oxidation state of the Chromium which in turn enables oxidation.
rgght the hydrogen ion in the acid react with the metal ion( POTASSIUM )in potassium dichromate n den Chromium ions are formed

Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1203 on: May 26, 2011, 04:06:46 pm »
we dont have to write half equation to show the colour changes in test for aldehyde and ketones

For tollens reagents or the Benedict solution ?

Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1204 on: May 26, 2011, 04:35:14 pm »
we dont have to write half equation to show the colour changes in test for aldehyde and ketones

For tollens reagents or the Benedict solution ?
Nah i dont think so...Just know the colour change
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Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1205 on: May 26, 2011, 04:46:09 pm »
For which organic molecules do we need to know the shapes and angles??
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Offline ~ Miss Relina ~

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1206 on: May 26, 2011, 06:08:33 pm »
Nah i dont think so...Just know the colour change
can u say the color change 8)
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Offline Aadeez || Zafar

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1207 on: May 26, 2011, 06:10:49 pm »
can u say the color change 8)

tollens reagant reacts with aldehyde to give silver mirrosing and benedicts reagant react with aldehyde to give red ppt. while ketones do not react with tollens nor with benedicts



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Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1208 on: May 26, 2011, 06:21:28 pm »
Hey i was pretending to be Smart -,- :P

Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1209 on: May 26, 2011, 06:24:56 pm »
For which organic molecules do we need to know the shapes and angles??

WOOT according to my memory you should know the shape Not the angles of organic ONLY

Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1210 on: May 26, 2011, 07:12:27 pm »
I need Definition for ;

Neucleophile

Electrophile

Free radical

Thanks :)

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Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1211 on: May 26, 2011, 07:19:53 pm »
I need Definition for ;

Neucleophile

Electrophile

Free radical

Thanks :)




Neucleophile :are ions or molecules with a lone pair of electrons that attack positive ions or positive centers in the molecule

Electrophiles :are reactive ions and molecules which attack negative ions or the negative centers in the molecules

Free radicals :are highly reactive single atoms, or a group of atoms with unpaired electrons

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1212 on: May 26, 2011, 07:29:34 pm »
Don't neucelophiles form dative covalent bonds too ?
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Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1213 on: May 26, 2011, 09:00:59 pm »
Don't neucelophiles form dative covalent bonds too ?


No it doesnt

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1214 on: May 27, 2011, 04:19:58 am »

Neucleophile :are ions or molecules with a lone pair of electrons that attack positive ions or positive centers in the molecule

Electrophiles :are reactive ions and molecules which attack negative ions or the negative centers in the molecules

Free radicals :are highly reactive single atoms, or a group of atoms with unpaired electrons

thanxx dear +rep