Radiochemistry questions

RHP-516 RADIOCHEMISTRY FINAL EXAM

Read the attached paper and answer all question.

Consult your textbooks, internet, library, etc., but do your own work.

A. “Preparation of sources of spectrometric quality from bulky natural samples requires many chemical operations in order to eliminate interfering elements. This task is particularly difficult for radium, for which few simple and specific separation methods are available.”

1. What is typical oxidation state of radium? Do you need to adjust it to another state prior to analysis? If yes, what oxidation state you need?

2. Explain what the interfering elements are for Ra:

a) name them, b) why and how they interfere;

3. What are the tracer and non-tracer methods for Ra?

4. In the case of a non-tracer method, how is calculated the recover yield of Ra? E) What elements and/or isotopes are used in tracer methods for radium?

5. Explain this statement: a) what are these isotopes, b) when and how they are applied (which separation and detection method), c) how to deal with their activity.

6. Detection of Ra-225. How its concentration is calculated from measured data; what are the interfering isotopes?

B. “Application of 223Ra or 224Ra as tracers requires, however, prior knowledge of their levels in the samples to be analyzed.”

7. Explain this statement: a) what are these isotopes, b) when and how they are applied (which separation and detection method), c) how to deal with their activity.

8. Detection of Ra-225. How its concentration is calculated from measured data; what are the interfering isotopes?

C. Ba-133 for tracing Ra-226:

9. Name all possible problems in using Ba-133 and experimental evidence of these errors.

D. Separation of Ra on hydrous manganese dioxide (scheme):

10. Why ammonium is added to the MnCl2 and KMnO4 solution?

11. Write the equation of their interaction.

12. Permanganate KMnO4 is pink and MnCl2 is colorless. What color will you observe upon addition of ammonia?

13. Why the precipitation step is repeated?

14. After filtration, the filtrate is discarded. What does it contain?

15. What is the compound precipitated and caught on the filter?

16. In the next step, the precipitate is dissolved by addition of the next chemicals. What is the role of each of them?

a) acetic acid

b) ascorbic acid

c) EDTA

17. What is the color of the resulting solution?

18. The filtration step is repeated. Why? What are we removing/retaining in this step?

19. At the next step, the filtrate undergoes treatment with solutions of a barium salt, propanol, Na2SO4 and seeds of BaSO4.

a) What salt of barium besides the seeds of barium sulfate, is added?

b) What is the role of each additive in this step?

20. After this treatment, the third filtration comes. Explain:

a) What does happen here?

b) What are the colors of the filtrated precipitate and the passed-through filtrate?

21. Why both the Ba(by gamma) and Ra(alpha) are counted, and how are these data combined?

22. Write equation or formula for calculation of Ra.

23. What does happen when strong HCl (9M) and a little bit of H2SO4 is added to the filtrate?

24. Explain the separation mechanism on the column with Dowex resin.

25. What is retained and what passes through?

26. Where is U (now separated from Ra)? What does happen when you apply water?

27. What is the role of alcohol in electroplating of radionuclides for alpha spectrometry?

28. What is the emanation method?