Chemistry of actinides

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1. Chemistry of actinides CECH-303 UNIT-3(B) BY- Ms MAYURI R SOMPURA HJD INSTITUTE - KUTCH

2. SYMBOLS AND NAMES OF ACTINIDES:-

3. TRANSURANIC ELEMENTS :- Elements beyond uranium (Z=92) are known as transuranic elements. Preparation of transuranic elements :-

4. TRANSURANIC ELEMENTS :- Preparation of transuranic elements :-

5. Extraction of thorium :- Ores : - ores Chemical name Thorianite Thorium oxide Thorite Thorite silicate Cheralite Silicates and phosphates of Th , Ca, Ce monazite Phosphates of Ce, Y, La, Th

6. Extraction of thorium :- ores : - Indian monazite sand is topmost grade in the world ( seacoast of Kerala state ). Extraction of thorium is difficult because rare earth elements are present in the ore. They resemble their chemical properties with thorium.

7. Extraction of thorium :- Concentration and formation of ThO 2 :- The ore is freed from major chunks of siliceous impurities either by mechanical washing or by magnetic separation. Treated with conc. Sulphuric acid in cast iron pans. The pasty mass is added to cold water and stirred – impurities like sand and other minerals settle down. The clean top solution is separated which contains phosphates of thorium and rare earth elements. This acidic solution is neutralized with alkali. We here get precipitates of thorium phosphate.

8. Extraction of thorium :- Concentration and formation of ThO 2 :- The precipitates are removed, dissolved in minimum quantity of acid. It is then neutralized again to get phosphate of thorium as precipitate. It is dissolved in conc. Nitric acid 6 M. Treated with KIO3 ( potassium iodate )to get thorium iodate. The precipitate is dissolved in HCl and re-precipitated with oxalic acid. It gives thorium oxalate. Thorium oxalate is ignited to give thorium oxide.

9. Preparation of thorium :- Metallic extraction is difficult because metal is highly reactive in its molten state.

10. Preparation of thorium :- Metallic extraction is difficult because metal is highly reactive in its molten state.

11. Properties of thorium :- Melting point is -1750℃. Amorphous as well as crystalline. At very low temperature it shows super conducting properties. Burns brilliantly with sparks ( ThO 2 ) Highly electropositive. Combines with hydrogen vigourously forming ThH4 Thorium is radioactive.

12. Uses of thorium :- Fuel rod manufacture for atomic reactors. Thorium oxide is used in preparation of incandescent gas. Medically used in treatment of cancer. Thorium nitrate is used to estimate fluorides volumetrically using methyl red indicator. Only ThO 2 is a stable compound of thorium.