2014年5月IB化学SL真题下载-Paper3

2014年5月IB化学SL真题下载-Paper3

1. (a) Describe the essential difference between the emission spectrum of sodium and the absorption spectrum of sodium.

(b) Identify the fi ve missing components in the following table.

(c) Other than to identify the presence of a particular element, state one use of atomic absorption spectroscopy.

 

2. (a) The mass spectrum of iodoethane, C2H5I, shows three prominent peaks with m/z values of 156, 127 and 29. Identify the ions responsible for each of these three prominent peaks. 

156:

127:

29:

(b) Bromine contains two isotopes, 79Br and 81Br, in approximately equal amounts. Predict the m/z values of the prominent peaks in the mass spectrum of bromoethane, C2H5Br.

 

3. A sample is known to contain three different amino acids. After carrying out paper chromatography using a solvent made up of propan-1-ol, water and ammonia, the following chromatogram was obtained once the spots had been developed with ninhydrin.

(a) Calculate the Rf values for the two spots. 

Spot 1:

Spot 2:

(b) Suggest a reason why only two spots are present.

(c) Suggest how the chromatography experiment with the same sample could be altered in order to obtain three spots.

4. Two students were provided with three different isomers of C3H6O2.

They were asked to suggest how the isomers could be distinguished and positively identified from each other using spectroscopic techniques. Student A said that they could be positively identifi ed just from their infrared spectra. Student B said that they could be positively identified just from the number of peaks and the areas under each peak in their 1H NMR spectra.

Evaluate these two claims and suggest how any possible limitations could be overcome using the same spectroscopic technique.

Student A / Infrared:

Student B / 1H NMR:

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