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Chemistry P4| A2 only
- Thread starter smzimran
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you deleted the post histephenson007 .... 
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you deleted the post histephenson007 ....
There is no Q3 i) ii) ... do u mean Q3. d i) ii) ??? (In that case, the only possible solution we could agree on was to try the trial and error method.....
)For Q4 c) Because we have to find out which one of these oxidation processes are likely to occur, we need to find out the E cell of both these process. The oxidation with the higher E cell is more likely to occur.
These are 2 solution:
-Fe2+ in acid
-Fe(OH)2 in alkaline
Sorry, internet got dced
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oh yeah , sorry it was 3 d ...
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And this skeletal formulae thingie is not working for me ..
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_43.pdf
Q5(c)
please help
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_43.pdf
Q5(c)
please help
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7c too ... mass spectometry and NMR uhhhhhhhhhhh .... i'm unable to attempt these questions at all despite of going through the topics in OCR and application booklet ... it was tedious studying them maybe that's why i couldn't grasp much ...
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which part is not working?!
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check out part c of Q5... they've asked to draw skeletal formulae... i'm unable to attempt it ... all my skeletal formulae went wrong
histephenson007 can u answer me this one pls!?
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explain may/june 2007 paper 4 q 4 part a n b
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s07_qp_4.pdf
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s07_qp_4.pdf
to find the no. of carbon atoms, always use this formula---> 100/1.1 * (M+2/M)
and if M:M+2 is 3:1 ==> chlorine atom is present
if M:M+2 is 1:1==> bromine atom is present
and for the determining the molecular structure of the organic compound, u have to use the Data Booklet...
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For 7.c)i) You'll hav to use this formula : No. of Carbon atoms = [(100/1.1) * (M+1/M)] . So, you'd get 3 Carbon atoms.
ii) There was M+2 peak present which had similar height to the M peak. This sort of peaks can only be formed with Bromine, because in the booklet, it is the only element we learned to have a 1:1 ratio abundance in its isotopes.
iii) Only one because there are only the M and M+2 peaks were in the spectrum ( because the question gave the M:M+1 ratio, we are to assume that the M+1 peak was solely caused by the 13C isotope). If there were more than one Bromine atoms, there could have been the 1:2:1 peak ratio thingies found.
iv)From 3 Carbons and 1 Bromine, we can get the empirical formula : C3H7Br
In the NMR,
There is one peak with 6H, but the there are only 3 Carbon atoms, so it isn't possible for a benzene ring to be there. So, there must be two -CH3 s on either side of a central carbon.
And the other 1H peak must've been formed by the hydrogen on the central Carbon atom.
So, the structure shouldbe CH3CH(Br)CH3
I recommend reading the chemguide version for NMR. It is very very very helpful
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thanks alotttttttt
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First, we need to get the Ka value from the pKa ..
pKa=-log(Ka)
So, Ka = 10 ^(-4.76)
The acid equation is : CH3COOH <---> (H+) + CH3COO-
So, Ka = ([H+]*[CH3COO-]) / [CH3COOH]
Re-arranging the equation: [H+] = (Ka*[CH3COOH]) / [CH3COO-]
But, we don't know what [CH3COO-] is,
So, we hav to find it with the formula C = {n(H+) - n(OH-)} / V
So, C = (0.1*0.01-0.01*0.25) / 0.02 = 0.075
Then, we can calculate for the H+ with the above reaction. And then pH. My teacher just used some pH = 4.76 + log(0.05/0.075), but I don't understand why.
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Think of it as a free-radical substitution reaction and add chlorine on each Carbon atom. Beware with the left ones.check out part c of Q5... they've asked to draw skeletal formulae... i'm unable to attempt it ... all my skeletal formulae went wrong
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Hey frens, has anyone got any notes on plastics!! thermosetting and thermoplastics..................... if so plz post or plz share the link
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http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_42.pdf
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_ms_42.pdf
Q2 a (i) how did we get the order with respect to H+ ?
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_ms_42.pdf
Q2 a (i) how did we get the order with respect to H+ ?
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By comparing 1 and 2, we get [CH3CHO] is 1st order.
By comparing 2 and 3, we get [CH3OH] is 1st order.
Then by comparing 1 and 4:
[CH3OH] becomes twice large, so does [H+].
We already know that [CH3OH] is 1st order, so it being twice large shall double the rate. But actually, the rate quadruples (4 times large).
The extra doubling effect comes from [H+]. It doubles to give a double effect. Therefore it is 1st order.
why did u subtract the no.of moles??