Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 253787 times)

Offline dk bose

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1695 on: April 17, 2012, 09:23:24 am »
i have got an urgent doubt..here it is..- A 1.0 mol dm-3 solution of rubidium chloride is made when 1 mole of rubidiun chloride is added to water.RbCl (s)+aq- Rb+(aq)+Cl-
At 298K,the enthalpy change on dissolving is +19kj mol-1.
(a)Calculate the entropy change in the system

Offline dk bose

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1696 on: April 17, 2012, 09:32:56 am »
i have got an urgent doubt..here it is..- A 1.0 mol dm-3 solution of rubidium chloride is made when 1 mole of rubidium chloride is added to water.RbCl (s)+aq- Rb+(aq)+Cl-
At 298K,the enthalpy change on dissolving is +19kj mol-1.
(a)Calculate the entropy change in the system
plzzzz solve this doubt and post the solutions as fast as possible...plzzz help me people!!!!!!

Offline KJ1995

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1697 on: May 01, 2012, 07:54:22 pm »
Hello guys, i would really appreciate your help.

How should i study Unit 6B chemistry. Are there any helpful books, please post the download links.. And what practicals should i know from AS and A2 for Unit 6B

Many thanks

Offline MKh

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1698 on: May 03, 2012, 10:58:51 am »
How should i study Unit 6B chemistry. Are there any helpful books, please post the download links.. And what practicals should i know from AS and A2 for Unit 6B
The Chemistry laboratory skills II exam consists of 3 sections: qualitative analysis (identfying unknown compounds), quantitative analysis (calculations, graphs etc.) and Preparation (explaining the steps in a given experimental procedure for carrying out a preparation) of organic and inorganic compounds.

Check the Practical Assessment section in the Edexcel A2 Chemistry Revision Guide which is available for download in here in SF - use the search engine to search for the download link.
You will find very helpful information in that section. From the Revison Guide, I quote:

Qualitative analysis
Chemical reactions and tests that may be included in this section include:
- Any of those listed for Unit 3 (therefore you will also have to check the qualilative analysis section of the Edexcel AS Chemistry Revision Guide which is also available for free download here in SF)
- The reactions of the transition metal ions in solution with aqueous sodium hydroxide and with aqueous ammonia both added untl in excess (see pg 81 of guide)
- Ligand exchange reactions in copper (II) complexes (pg 79 of guide)
- The redox chemistry of chromium (pg 78 of guide)


[And the list goes on. It is better if you check the Guide itself]

Quantitative analysis
At least one of the following will be included in this assessment:
- pH titration
- Following the rate of a reaction
- Potassium manganate (VII) titration
- Finding the activation energy of a reaction


Preparation
Laboratory practices needed for preparation:
- Those developed at AS, such as heating under reflux and distillation
- Purification of an impure solid product by recrystallization from hot, saturated solvent
- Melting temperature determination
- Drying solid by filtration under reduced pressure - using a Buchner funnel and flask


Do make sure that you know how to draw labelled diagrams for the apparatus used to carry out distillation, reflux, filtration under reduced pressure and the ones used to determine melting and boiling temperature of a compound

Hope this helps.

Offline -Cornea

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1699 on: September 28, 2012, 02:02:35 pm »
is anyone over here doing AL chemistry if so i need a proof for bohr's theory of atomic structure it's not actually a proof it's the steps from where did we we get tht 109678 number ....Thanks in advance :)
« Last Edit: September 28, 2012, 02:04:12 pm by -Cornea »
Laughter is the shock absorber that eases the blow of life ! =)

Offline Deadly_king

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1700 on: September 28, 2012, 02:38:49 pm »
is anyone over here doing AL chemistry if so i need a proof for bohr's theory of atomic structure it's not actually a proof it's the steps from where did we we get tht 109678 number ....Thanks in advance :)

It's just a constant which you need to use ;)

I doubt you need to know how it is obtained!

http://library.thinkquest.org/19662/low/eng/model-bohr.html

Offline baditude

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1701 on: December 11, 2012, 04:41:38 pm »
Can  someone please help me with January 2010, unit 4 Question 26
ASAP please, i've got an exam tomorrow.

Offline Deadly_king

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1702 on: December 13, 2012, 02:04:19 pm »
Can  someone please help me with January 2010, unit 4 Question 26
ASAP please, i've got an exam tomorrow.

I don't have the paper :/

Can you post the question itself or provide a link to the paper?

Offline Maheen.S

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1703 on: December 18, 2012, 07:35:25 pm »
hey could anyone please link me to 'edexcel george facer teacher guide' for A2 bio and Physics...i got it for A2 chem...(AS if possible for chem and physics)....pleaseeee anyone?? :) thanks!

Offline Za_shadow

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1704 on: December 31, 2012, 01:05:54 pm »
plzzzz helppp mee

jan 09 question 23 c i )
why did he multiply 2*0.01/2 *100
and didn't multiply 30*0.5/30 *100

jan 2010 Q5  why A  i don't understand the question :(

and Q6 why A not C

May 2010 Q4 (a) why B ??????

May 2011 Q8 why C ???

and Q9 why C ???

really appreciate anyy helpp and thank u veryyyyy mucchhhh

Amelia

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1705 on: December 31, 2012, 03:05:25 pm »
plzzzz helppp mee

jan 09 question 23 c i )
why did he multiply 2*0.01/2 *100
and didn't multiply 30*0.5/30 *100

jan 2010 Q5  why A  i don't understand the question :(

and Q6 why A not C

May 2010 Q4 (a) why B ??????

May 2011 Q8 why C ???

and Q9 why C ???

really appreciate anyy helpp and thank u veryyyyy mucchhhh

I'm sorry, but can you post the links of the question paper or the questions itself? It will be easier to answer. Thank you and sorry.


Offline NotAbod

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1707 on: January 02, 2013, 03:50:45 pm »
First question: If you are to take initial and final reading, error is multiplied by 2. This applies to balance, burette etc.
No idea about the rest, I suck at unit 1 Chemistry. :(

Offline DrThamooth

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1708 on: May 10, 2013, 09:56:24 pm »
Hii all ,
I really need the CGP chemistry A2 guide
i cannot find it anywhere x_x
if any of you have the link maybe or you can upload it , it would really be appreciated ..
thank you :D

Offline Amany ali

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1709 on: May 12, 2013, 06:11:00 am »
CAN Anybody teach me how to draw hesses law cycle ...??? i donno a bi of it :/  ??? ???