CIE Nov 2013 v3 Paper 4 Q8

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Examiners For Use Instrumental analysis plays an increasingly important role in modern chemistry. Two important techniques are NMR spectroscopy and X-ray crystallography. 16 (a) Both techniques use part of the electromagnetic spectrum. Which technique uses radiation with the longer wavelength, and in which part of the spectrum is it found?[1] (b) NMR spectroscopy provides detailed information about protons, but X-ray crystallography is unable to detect them. Explain these facts.[2] (c) The protein found in hair contains the amino acid cysteine, C3H7SNO2. Crystalline cysteine was examined using X-ray crystallography. State which atom produced the strongest re ection, explaining your answer.[1] (d) Compound P is an alcohol that can be converted into compound Q in the following reaction sequence. PCxH6OQ Spectral analyses of P and Q were carried out. (i) The mass spectrum of P shows an M : M+1 peak ratio of 4.5 : 0.15. Calculate the number of carbon atoms in P.UCLES 2013 9701/43/O/N/13<br /> Examiners For Use The NMR spectra of P and Q are shown below. 17 6 5/ ppm 11 10 12 10 6/ ppm (ii) In the spectrum of P, clearly label the peak due to the OH group with an X. (iii) State how many different proton environments are present in compound Q.(iv) What evidence is there in these spectra that P is a primary rather than a secondary alcohol?(v) Draw a structure for Q.UCLES 2013 9701/43/O/N/13 [Turn over [6] [Total: 10]<br />

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