Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 256868 times)

Offline AS01

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1635 on: January 09, 2012, 07:06:05 pm »
its the same here too i finished doing all of the past papers and i don't have any left can you plz email me some of the questions on chemistry too.
by the way how come you know everything have you completed your A levels?

Offline AS01

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1636 on: January 12, 2012, 07:19:49 pm »
hey can you plz say be what is the equation of bond enthalpy and mean bond enthalpy?
i know there  definition. but the way they ask in exam i am unable to recognise whether which is bond enthalpy and which one is not.
for example for the reaction given below
1/4CH4(g)=>1/4C(g)+H(g)
why is this the mean bond enthalpy of CH4 bond not CH4(g)=>C(g)+2H2(g)?
plz explain this in detail.

Offline AS01

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1637 on: January 12, 2012, 07:23:08 pm »
The human body contains around 0.025 g of iodine molecules, I2. Which of the
following shows the number of iodine atoms in 0.025 g of I2?
The Avogadro constant is 6.02 × 1023 mol–1.
Why the answer is this:-
0.025/126.9*6.02*10^23

not 0.025/253.8*6.02*10^23?

Offline Blizz_rb93

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1638 on: January 13, 2012, 01:47:32 am »
The human body contains around 0.025 g of iodine molecules, I2. Which of the
following shows the number of iodine atoms in 0.025 g of I2?
The Avogadro constant is 6.02 × 1023 mol–1.
Why the answer is this:-
0.025/126.9*6.02*10^23

not 0.025/253.8*6.02*10^23?


i was wondering the same thing :/

& i have smth also

this is from Jan 2011 unit 1

question 3:

The Avogadro constant is 6.0 x 10^23 mol-1. Therefore the numbers of atoms in 1 mol of carbon dioxide is :

why is the answer 1.8 x 10^24 and not 6.0 x 10^23 :/


Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1639 on: January 13, 2012, 11:33:21 am »
The human body contains around 0.025 g of iodine molecules, I2. Which of the
following shows the number of iodine atoms in 0.025 g of I2?
The Avogadro constant is 6.02 × 1023 mol–1.
Why the answer is this:-
0.025/126.9*6.02*10^23

not 0.025/253.8*6.02*10^23?


I suppose because the question asks for atoms of iodine and not molecules?
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Offline Deadly_king

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1640 on: January 13, 2012, 06:29:57 pm »
I suppose because the question asks for atoms of iodine and not molecules?

Exactly ;)

Each I2 molecule consists of 2 Iodine atoms ;)

Offline MKh

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1641 on: January 14, 2012, 11:39:07 am »
Exactly ;)

Each I2 molecule consists of 2 Iodine atoms ;)

Hi, just wanted to ask if u have done A2 Chemistry? Have you got any resources to prepare for the preparation question of the international written alternative to practical paper?
Any useful tips r also welcome.
Thanks in advance.

Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1642 on: January 14, 2012, 11:41:06 am »
He's a college student ,and besides he did CIE  not Edexcel (:
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Offline Deadly_king

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1643 on: January 14, 2012, 02:36:24 pm »
Hi, just wanted to ask if u have done A2 Chemistry? Have you got any resources to prepare for the preparation question of the international written alternative to practical paper?
Any useful tips r also welcome.
Thanks in advance.

I have completed my A2 Chemistry a year ago so I may not remember everything , am afraid. And yeah, I did CIE, not EDEXCEL ;)

Am sorry I don't even know how your paper is especially the Alternative to Practicals for in my time I had done Practicals itself  :-\

But you can ask any doubt and I'll try to help as much as  I can Insha Allah :)

Thanks Miss Invisble ;)

Offline MKh

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1644 on: January 14, 2012, 06:10:34 pm »
^Oh yes, I knew that u did ur A/Ls from the CIE board but just wanted to confirm if u did A/L Chem as well.

Sure, INSHA ALLAH.

Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1645 on: January 16, 2012, 08:07:10 pm »
Can anyone give me a better explaination for this question. I dont understand the markscheme :S

Q: Explain why primary and tertiary bromoalkanes are hydrolyssed by different mechanisms.

It is from June 2010 unit 4

Thanks
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Offline Deadly_king

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1646 on: January 17, 2012, 01:02:01 pm »
Can anyone give me a better explaination for this question. I dont understand the markscheme :S

Q: Explain why primary and tertiary bromoalkanes are hydrolyssed by different mechanisms.

It is from June 2010 unit 4

Thanks

I had the same doubt some time ago :P

Check my thread :P

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1647 on: January 17, 2012, 03:01:54 pm »
anyone sat unit 6 B exam ????

I need to discuss it but cann't find anyone........so I just was wonderiing if anyone can inbox me or somethnig.... :-\
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Offline MKh

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1648 on: January 17, 2012, 03:57:36 pm »
anyone sat unit 6 B exam ????

I need to discuss it but cann't find anyone........so I just was wonderiing if anyone can inbox me or somethnig.... :-\

I sat for the Chemistry unit 6b exam. How did urz go, dear?

Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1649 on: January 17, 2012, 04:40:04 pm »
If you are a man who degrades women then allow me to respectfully remind you that you came from ONE

Reminder to myself: Stop worrying and start working

SF magazine 2012 - Download here