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| Rhodium | Rhodium | Rodij | Rodio | Rhodium | ||||||||||||||||||||
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Rh Rhodium |
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- Rhodium was discovered by William Hyde Wollaston (England) in 1804. The origin of the name comes from the Greek word rhodon meaning rose. It is hard, silvery-white metal. Inert in air and acids. Reacts with fused alkalis.
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TRANSITION ELEMENT: COBALT GROUP | |
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| Relative atomic mass: | 102.90550(2) | Electronic configuration: | [Kr] 4d8 5s1 |
| Formal oxidation number: | +3 | Electronegativities: | 2.28 |
| Thermal conductivity: | 150 W m-1 K-1 | Electrical resistivity (20 °C): | 4.51 μΩcm |
| Atomic radius: | 134.5 pm | Standard state (20 °C): | solid |
| Density (g dm-3): | 12410 (293 K) 10650 (m.p.) |
Molar volume (cm3 mol-1): | 8.29 (293 K) 9.66 (m.p.) |
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THERMAL PROPERTIES | |
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| Melting point: | 1964 °C | Heat of fusion: | 21.55 kJ mol-1 |
| Boiling point: | 3695 °C | Heat of vaporization: | 494.34 kJ mol-1 |
| Critical temperature: | 6727 °C | Heat of atomization: | 555.59 kJ mol-1 |
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IONIZATION ENERGIES AND ABUNDANCE | |
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| 1st ionization energy: | 719.68 kJ mol-1 | Abundance of element (air): | - ppm |
| 2nd ionization energy: | 1744.47 kJ mol-1 | Abundance of element (Earth's crust): | 0.005 ppm |
| 3rd ionization energy: | 2996.86 kJ mol-1 | Abundance of element (oceans): | 1E-10 ppm |
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ISOTOPES | |
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Isotopes | Relative atomic mass | Abundance (%) |
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103Rh | 102.905504(3) | 100 |
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MINERALS AND USES | |
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- Rhodium is obtained as a by-product of nickel production. Used as a coating to prevent wear on high quality science equipment and with platinum to make thermocouples. The price of 99.9 % pure rhodium sponge is 1698.40 € for 10 g.
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REDUCTION POTENTIALS | |
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Balanced half-reaction | Eo / V | Annotation |
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Rh3+ + 3e-  Rh(s) |
+0.8 | |
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RhCl63- + 3e- Rh(s) + 6Cl- |
+0.44 | |
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Rh2O3(s) + 6H+ + 6e- 2Rh(s) + 3H2O |
+0.87 | |
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RhO2 + 4H+ + 6Cl- + e- RhCl63- + 2H2O |
+1.4 | |
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RhO2+ + 2H+ + e- Rh3+ + H2O |
+1.40 | |
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RhO42- + 6H+ + 2e- RhO2+ + 3H2O |
+1.46 | |
