■ Vodacom 4G 20:13 21% := ACA470S Assignment Done Û ACA470S Assignment Due: 12 April 2024 Total: 30 Q1. Give reasons for the following practices in voltammetry and polarographic analysis. (6) (a) Degassing of the solution before analysis. (b) Use of large excess of an inert electrolyte 50 to 100 times more concentrated than analyte. (c) Utilisation of two or three electrodes for analysis. Q2. Explain why the following scenarios occur in voltammetry/polarography? (a) Why square wave voltammetry (SWV) is the commonest technique used? (b) Why is pulsed voltammetry more sensitive than linear sweep voltammetry? (c) Why is mercury electrode with its exceptional properties is not universally used? (9) Q3. Aluoride ISE immersed in 1 x 10-2 mol dm³ solution of sodium fluoride gives a potential of 35,2 mV and when it is immersed in a tooth paste solution it gives a potential of 30,2 mV. What is the concentration of fluoride ion in the toothpaste (4) Q4. The concentration of Cr (IV) in seawater was determined by polarography as follows; A 50.0 mL sample was analysed, resulting with a peak current of 0.886 microamps. After addition of a 5.00 microliter spike of 10.0 ppm Cr (IV) in the sample, a measured peak current of the resulting solution was 2.52 microamps. Calculate the ppm Cr (IV) in the sample of seawater. (5) Q5. What are the applications of the following stripping techniques. Explain your answer. (6) (a) Anodic stripping (b) Cathodic stripping (c) Absorptive stripping
■ Vodacom 4G 20:13 21% := ACA470S Assignment Done Û ACA470S Assignment Due: 12 April 2024 Total: 30 Q1. Give reasons for the following practices in voltammetry and polarographic analysis. (6) (a) Degassing of the solution before analysis. (b) Use of large excess of an inert electrolyte 50 to 100 times more concentrated than analyte. (c) Utilisation of two or three electrodes for analysis. Q2. Explain why the following scenarios occur in voltammetry/polarography? (a) Why square wave voltammetry (SWV) is the commonest technique used? (b) Why is pulsed voltammetry more sensitive than linear sweep voltammetry? (c) Why is mercury electrode with its exceptional properties is not universally used? (9) Q3. Aluoride ISE immersed in 1 x 10-2 mol dm³ solution of sodium fluoride gives a potential of 35,2 mV and when it is immersed in a tooth paste solution it gives a potential of 30,2 mV. What is the concentration of fluoride ion in the toothpaste (4) Q4. The concentration of Cr (IV) in seawater was determined by polarography as follows; A 50.0 mL sample was analysed, resulting with a peak current of 0.886 microamps. After addition of a 5.00 microliter spike of 10.0 ppm Cr (IV) in the sample, a measured peak current of the resulting solution was 2.52 microamps. Calculate the ppm Cr (IV) in the sample of seawater. (5) Q5. What are the applications of the following stripping techniques. Explain your answer. (6) (a) Anodic stripping (b) Cathodic stripping (c) Absorptive stripping
Chapter27: Molecular Fluorescence Spectroscopy
Section: Chapter Questions
Problem 27.11QAP
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