76584
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http://www.ocr.org.uk/qualifications...y-a-h034-h434/
The paper is june 2012 and the question is 5b, the last question on the paper. You should see it if you scroll down the page and click past paper, theres markschemes to. I don't understand how you get the answer even with the mark scheme, For example Where it says the answer is ch3--c=o for the peak at 2.2 I dont understand how you know whether its CH2, CH3, CH etc..
Another exampleI dont understand how you know 2.8ppm either where it is a benzene ring than CH or CH2...how do you know which and why? Could someone maybe answer the entire question and explain it thanks
eak at 2.8 shows C6H5–CH OR C6H5–CH2eak at 2.8 shows C6H5–CH OR C6H5–CH
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username986184
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(Original post by 76584)
http://www.ocr.org.uk/qualifications...y-a-h034-h434/
The paper is june 2012 and the question is 5b, the last question on the paper. You should see it if you scroll down the page and click past paper, theres markschemes to. I don't understand how you get the answer even with the mark scheme, For example Where it says the answer is ch3--c=o for the peak at 2.2 I dont understand how you know whether its CH2, CH3, CH etc.. Because the integration is 3 so it's methyl
Another exampleI dont understand how you know 2.8ppm either where it is a benzene ring than CH or CH2...how do you know which and why? Cant understand what you are asking hereCould someone maybe answer the entire question and explain it thanks
eak at 2.8 shows C6H5–CH OR C6H5–CH2eak at 2.8 shows C6H5–CH OR C6H5–CH
see above
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76584
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(Original post by TeachChemistry)
see above
Sorry i'll try to be more clear. Basically in the markscheme it says the peak at 2.8ppm is c6h5-CH2 or instead of the ch2 it can be just ch. So basically a carbon with one or two hydrogens is attached to the benzene ring. My question is how would i find this out from the information given? As i got a nearly identical answer but in my answer i put the ester group first then the carbon chain but the mark scheme did the opposite and did the carbon chain and then the ester group after it.So i guess my question is how do you know the order of the structure and second the last two points in the mark scheme for 2.8ppm and 4.4ppm, how do you know how many hydrogens to attach to the carbon because i wouldnt know whether it was ch ch2 or ch3
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username986184
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(Original post by 76584)
Sorry i'll try to be more clear. Basically in the markscheme it says the peak at 2.8ppm is c6h5-CH2 or instead of the ch2 it can be just ch. So basically a carbon with one or two hydrogens is attached to the benzene ring. My question is how would i find this out from the information given? As i got a nearly identical answer but in my answer i put the ester group first then the carbon chain but the mark scheme did the opposite and did the carbon chain and then the ester group after it.So i guess my question is how do you know the order of the structure and second the last two points in the mark scheme for 2.8ppm and 4.4ppm, how do you know how many hydrogens to attach to the carbon because i wouldnt know whether it was ch ch2 or ch3
you are mis-interpreting the MS. What it says is

Peak at 2.8 shows C6H5–CH OR C6H5–CH2 
Just require C6H5–CH as testing environment here

In other words, it is enough to identify the environment from your data sheet without specifically saying there are two protons in that environment in this particular compound.

Please post a picture of the final structure YOU arrived at then I will be able to tell you why it does not fit the data.
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Again, the key is the numbers to the right of each peak... Above the spectrum is the line: "The numbers on the NMR spectrum represent the relative peak areas". These numbers tell you how many H atoms there are in each environment.

i.e. there are 2x H atoms attached to the C attached to the benzene ring.
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(Original post by TeachChemistry)
you are mis-interpreting the MS. What it says is

Peak at 2.8 shows C6H5–CH OR C6H5–CH2 
Just require C6H5–CH as testing environment here

In other words, it is enough to identify the environment from your data sheet without specifically saying there are two protons in that environment in this particular compound.

Please post a picture of the final structure YOU arrived at then I will be able to tell you why it does not fit the data.
hey these are the pictures http://imgur.com/a/DwhAI thats my answer to the question..i think i got around 5 not sure
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(Original post by 76584)
hey these are the pictures http://imgur.com/a/DwhAI thats my answer to the question..i think i got around 5 not sure
See attached.
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(Original post by TeachChemistry)
See attached.
thanks for the help, i think i get it now. Really appreciate it
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