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Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 246759 times)

Amelia

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #780 on: March 14, 2011, 04:17:13 pm »
Quote from: vicoden on March 13, 2011, 07:24:00 pm
Hi, I would like to know how to use the anti-clockwise rule to help me predict whether a reaction will occur.
 i hope someone can explain for me i tried to read about it alot but i cant seem to understand how the arrows help to predict whether a reaction will occur or no ): ?

here are examples :

Using the anti-clockwise rule:
( image attached down )

The reverse reaction is favored, so MnO2 and HCL will not react.


how did they figure out just by arrows that it will not react D: ???



Good explanation here - http://www.chemistry-react.org/go/Faq/Faq_28302.html
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Offline Blizz_rb93

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #781 on: March 15, 2011, 04:44:21 pm »
Can anybody help me understand 2 things

1) Dot & Cross Diagrams, i just want to get the basic idea of what were supposed to do here cuz sometimes they get confusing :(

2) Ionic equations, how do we write ionic equations?

Thank you =)
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Amelia

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #782 on: March 15, 2011, 05:35:58 pm »
Quote from: Blizz_rb93 on March 15, 2011, 04:44:21 pm
Can anybody help me understand 2 things

1) Dot & Cross Diagrams, i just want to get the basic idea of what were supposed to do here cuz sometimes they get confusing :(


It's simple enough.  ;)
Dot and Cross diagrams are used to show the electronic configuratoins of elements and ions. The elements of one element in the compund are shown by dots, those of the second element by crosses.



Quote
2) Ionic equations, how do we write ionic equations?

Thank you =)

Here -  http://wiki.answers.com/Q/How_do_you_write_a_net_ionic_equation
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Offline SoONa

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #783 on: March 15, 2011, 08:01:07 pm »
Hey ... so i really need to know what experiments and subjects i need to know for unit 3 ?????
thanks in advance
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Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #784 on: March 16, 2011, 03:04:15 pm »
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Offline SoONa

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #785 on: March 16, 2011, 03:23:26 pm »
Thank UUUUUUUUU it definetly helps ;D i see the light now  :P
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Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #786 on: March 16, 2011, 05:18:00 pm »
Quote from: SoONa on March 16, 2011, 03:23:26 pm
Thank UUUUUUUUU it definetly helps ;D i see the light now  :P

LOL :D your welcome  :D
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Offline Blizz_rb93

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #787 on: March 16, 2011, 05:46:35 pm »
can anyone let me know good websites for chemistry??
right now i need some help in the moles section, and everything related to it

thank you



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Amelia

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #788 on: March 16, 2011, 06:35:27 pm »
Quote from: Blizz_rb93 on March 16, 2011, 05:46:35 pm
can anyone let me know good websites for chemistry??
right now i need some help in the moles section, and everything related to it

thank you


Check these - http://www.chemguide.co.uk/
                    http://www.docbrown.info/page04/4_73calcs.htm

I hope they help.  :)
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Offline EMO123

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #789 on: March 16, 2011, 07:11:10 pm »
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Offline ~ Miss Relina ~

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #790 on: March 17, 2011, 11:30:50 pm »
are we supposed to know formation of nitric acid , extraction and electrolysis of aluminium ,electrolysis of brine to form clorine in the new edxecel specification of as-level or not [plz reply to me soon
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elemis

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #791 on: March 18, 2011, 03:18:18 am »
Quote from: Relina on March 17, 2011, 11:30:50 pm
are we supposed to know formation of nitric acid , extraction and electrolysis of aluminium ,electrolysis of brine to form clorine in the new edxecel specification of as-level or not [plz reply to me soon

Download the syllabus :  http://www.edexcel.com/migrationdocuments/GCE%20New%20GCE/International-spec-Chemistry.pdf
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**RoRo**

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #792 on: March 18, 2011, 02:55:03 pm »
In hybridization, when considering ethene, the C=C has a sigma bond formed by sp3-sp3 overlap and a pi bond formed by sp2-sp2 overlap, does the pi bond bring the two atoms closer to each other and hence the bond length of C=C becomes less than that of C-C?

& does a shorter bond mean that there's more attraction between the two atoms and that more energy will be required to separate them?
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Amelia

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #793 on: March 18, 2011, 04:13:05 pm »
Quote from: The Secret on March 18, 2011, 02:55:03 pm
In hybridization, when considering ethene, the C=C has a sigma bond formed by sp3-sp3 overlap and a pi bond formed by sp2-sp2 overlap, does the pi bond bring the two atoms closer to each other and hence the bond length of C=C becomes less than that of C-C?

& does a shorter bond mean that there's more attraction between the two atoms and that more energy will be required to separate them?


A double bond is composed of one single sp-sp bond and a second pi-pi bond, the first bond is already holding the atoms together, the pi-pi bond increases the strength of the bond and so draws the atoms closer together. This also results in the sp-sp bond strengthening as orbital overlap increases.

Greater the attraction between the nuclei and the electrons smaller will be the distance between them and so, yes; the double bond requires more energy to seperate them. 
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**RoRo**

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #794 on: March 18, 2011, 06:57:14 pm »
Quote from: Amelia on March 18, 2011, 04:13:05 pm

A double bond is composed of one single sp-sp bond and a second pi-pi bond, the first bond is already holding the atoms together, the pi-pi bond increases the strength of the bond and so draws the atoms closer together. This also results in the sp-sp bond strengthening as orbital overlap increases.

Greater the attraction between the nuclei and the electrons smaller will be the distance between them and so, yes; the double bond requires more energy to seperate them. 

Okay, thank you! :)

May I just confirm one more thing?

The products of incomplete combustion, I recall from IG's that it was carbon monoxide and water, but in my edexcel AS chemistry textbook, it says carbon [soot], carbondioxide and carbonmonoxide, so which one is right?
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