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Chemistry ppr 4 doubt

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nid404:

--- Quote from: moon on September 20, 2010, 06:55:18 pm ---why is the aminoacid  -ala - repeated twice and not  -gly-?

--- End quote ---

like I said it doesn't matter. Only the starting n terminal should be met and terminal end should be lys.

Greed444:
can anyone help on OCT/NOV 2007, Q5a, Q9a & Q9C(ii)

Deadly_king:

--- Quote from: Greed444 on September 24, 2010, 05:35:44 pm ---can anyone help on OCT/NOV 2007, Q5a, Q9a & Q9C(ii)

--- End quote ---

5. You should use the half ionic equations from the data booklet.

MnO4- + 8H+ + 5e ----> Mn2+ + 4H2O

H2O2 ----> O2 + 2H+ +2e

Then multiply the first equation by 2 while the second one is multiplies by 5 so as to balance the charges(electrons)

So you will obtain :
2MnO4- + 6H+ + 5H2O ----> 2Mn2+ + 8H2O + 5O2

NOTE : You will obtain 16H+ on the reactants side and 10H+ on the product size. Hence overall it will be only 6H+ on the reactants side.

Hope it helps.:)

Am still working on the two others.

Deadly_king:
9(a). Its quite complicated for me to explain that. I mean I cannot just give you the answer like that since you will not understand anything.

Take a look at this : http://www.chemguide.co.uk/analysis/nmr/background.html#top

From what you understand, then have a look at the marking scheme. Try to see if you understand how it works. Then put it in your own words. It will be better for you since you will understand what you are writing :)

9(c)(ii)
From the first part it is found that G contains 4 carbon atoms.

So now we interprete the spectra ( Am starting from the right)

First peak is a triplet with chemical shift of about 1.4 : It suggests a R--CH2--R ( from data booklet)
Second peak is a single peak with chemical shift 2 : It suggests a CH3--COOR
Third peak is a quartet with chemical shift about 4.3 : It suggests a CH3--R

Therefore by combining all these G is found to be ethyl ethanoate.

NOTE :If you don't understand how NMR works you'll not understand how i obtained the answer.

So do have a look at the notes first :)

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