Question

DR HALL'S QUESTIONS

Answer ALL questions of this section. Total marks for this section is 30. All questions are worth 5 marks, therefore, I demand an appropriately detailed answer to each question otherwise I will give a negative review. DO NOT COPY AND PASTE FROM ONLINE!!!!

1. Discuss the principles of operation of a Time of Flight Mass Analyser (TOF). Make use of labeled diagrams and schematics, where appropriate, to help explain your answer.

2. Select the correct method of thermal analysis to study the following physical processes and provide a reason for your choice:

               (i)         Measuring a glass transition temperature, Tg.

               (ii)        Determining pharmaceutical purity.

                                    (iii)       Comparisons of paint samples

3. Select the correct method of thermal analysis to study the following physical processes and provide a reason for your choice:

The composition of a mixed metal oxalate sample

Measuring a melting temperature, Tm, and

Comparison of synthetic fibers.

4. Sketch the voltage-time curves (waveforms) employed in the following types of voltammetry;

linear sweep voltammetry,

cyclic voltammetry, and

differential pulse voltammetry.

5. Ion selective electrodes are the only analytical technique for which you can utilize a two-point calibration curve. Explain the reasons for this.

6. The DSC trace of polyethylene terephthalate, PET, is shown below. Account for the thermal transitions shown on the thermogram.

0 165.7°C 7.91 cal/g 33.0 J/g 235.5°C 83.9°C -3 33.3° J/g 85.9°C 150.6°C 7.96 cal/g Use of generic equation -6 250.2°C 60 80 100 20 40 60 80200220 240 260 280 Temperature,C Differential scanning calorimetry output from a thermal instrument showing the thermal transition for polyethylene terphthalate.

Answer 1

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