Edexcel A2 Chemistry 6ch04/05 JUNE 2015 Watch

rasil23
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#741
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#741
(Original post by Nautic4l)
But they don't give it in the rate eqn?

Okay so why are they all same proton environment? Because they're all adjacent to a C with no H on it? Wait that sounds like it's for the splitting... Oh is it because they're all CH3??

I understand 11 now

Thank you so much!! You are one beautiful human being.
The statement says the rate will quadruple if the conc of pronanone and i2 is doubled, you can't know that for sure as you have to work out the order of the reaction with respect to iodine experimentally, so that statement is not correct.

Yes, because they're all CH3
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Nautic4l
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(Original post by rasil23)
The statement says the rate will quadruple if the conc of pronanone and i2 is doubled, you can't know that for sure as you have to work out the order of the reaction with respect to iodine experimentally, so that statement is not correct.

Yes, because they're all CH3
Oh shizzle I read the Q wrong haha! Yep deffo caught me out

Thank you
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frozo123
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#743
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(Original post by rasil23)
The statement says the rate will quadruple if the conc of pronanone and i2 is doubled, you can't know that for sure as you have to work out the order of the reaction with respect to iodine experimentally, so that statement is not correct.

Yes, because they're all CH3
Hello sorry forgot to reply to you aha
well for weak acids
you are squarerooting Kaxconc of the acid
so everytime you dilute by 10, pH only increases by 0.5
on the other hand for strong acids you just plug in the number into the -log and it increases by 1
they will award you marks by showing it mathematically
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jshah1997
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(Original post by MeeraP07)
For part a...
using Kw --> 10^-14÷0.2x2= 2.5x10^-14
-log(2.5x10^-14)=13.6

you times the conc of strontium hydroxide by 2 because theres two OHs in the formula (Sr(OH)2)

for part b...
moles of nitric acid= 20x1÷1000=0.02
moles of sodium hydroxide= 10x1÷1000=0.01
moles of excess acid= 0.02-0.01=0.01

conc of excess acid= 0.01x1000÷30=1/3 (30 is the total volume btw)
-log(1/3)=0.48
Thank youu!!
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HopefulDentist..
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#745
http://qualifications.pearson.com/co...e_20100127.pdf

how can you decide which method to use for question 8?
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rasil23
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(Original post by HopefulDentist..)
http://qualifications.pearson.com/co...e_20100114.pdf

how can you decide which method to use for question 8?
You sure you linked the right paper :P?
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aisha17
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In one type of HPLC, the stationary phase is non polar and a polar solvent is used as the eluent. Which of the following would travel through the chromatography column most quickly?
A. Tetrachloromethane
B. Chloro methane.
C. Iodine thane
D. Hexane
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rasil23
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#748
(Original post by aisha17)
In one type of HPLC, the stationary phase is non polar and a polar solvent is used as the eluent. Which of the following would travel through the chromatography column most quickly?
A. Tetrachloromethane
B. Chloro methane.
C. Iodine thane
D. Hexane
I think its B because polar solvents will travel more quickly due to the attraction between the solvent and the polar substance?
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HopefulDentist..
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#749
(Original post by rasil23)
You sure you linked the right paper :P?
changed the link now haha
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rasil23
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(Original post by HopefulDentist..)
changed the link now haha
Still hte same
but I went ahead and checked jan 2010 unit 4 question 8, if thats what you mean
The only viable one to check composition of substances is Gas-liquid chromatography, the other ones are just separation techniques?
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HopefulDentist..
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(Original post by rasil23)
Still hte same
but I went ahead and checked jan 2010 unit 4 question 8, if thats what you mean
The only viable one to check composition of substances is Gas-liquid chromatography, the other ones are just separation techniques?
reallly? oh gosh sorry!

ohh okay thankyou!!
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MeeraP07
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#752
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How do you know whether a reaction is zero or second order based on its half life? I understand it for a first order reaction
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cbfks
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(Original post by MeeraP07)
How do you know whether a reaction is zero or second order based on its half life? I understand it for a first order reaction
For a first order reaction half life will remain constant.

For a 2nd order reaction half life will increase.
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aisha17
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(Original post by rasil23)
I think its B because polar solvents will travel more quickly due to the attraction between the solvent and the polar substance?
Yep that's the answer
Thanks, all the best for tomorrow 👍
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Wannabe007
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(Original post by DCMed96)
acts as a catalyst really, the mechanism is given in chemguide, but i think we don't need it for exam tomorrow
http://www.chemguide.co.uk/physical/.../esterify.html

can't believe exam is tomorrow!!
Thank you! I guess I should first check chemguide and then ask here. Yeah, the mechanism is not needed but I just wanted to know so i can remember it better.


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Hairysweets
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#756
(Original post by Nautic4l)
Can anyone help with Jan 10 paper pleaseeee? Jun 10 I've had help with
Jan 10 Q1:

Increasing pressure shifts eql. to the right yes? So more PCl5 is formed.

Mole fractions are just the percentage/ratio that one molecule is representing out of the total, so if more PCl5 is formed: less moles of Cl2 + PCl3 are left. So now the moles of PCl5 are taking a bigger chunk of the total moles (Cl2 + PCl3 + PCl5). Does that make any sense?
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Wahid1
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All we need to know about hplc and glc is basically that 6 marker that came up once right?




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Hairysweets
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(Original post by Wahid1)
All we need to know about hplc and glc is basically that 6 marker that came up once right?




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Could you link me? We haven't been taught this so I'd love to have a go and see what;s needed!
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Wahid1
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(Original post by DCMed96)
Only one N in the slow step, so one N appears in the rate equation,

Question 7, neutral as although conc of H+ and Oh- increase there's no excess of either as both increase by same amount
check http://www.chemguide.co.uk/physical/...ia/kw.html#top
bottom of this page
In that link why can't you simply use equilibrium moles for example three?
2 moles of products and reactants...


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Wahid1
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(Original post by Hairysweets)
Could you link me? We haven't been taught this so I'd love to have a go and see what;s needed!
January 2011 question 21 part c


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