| Reactions of Selenium |
 Reactions with air |
| Selenium burns in air to form the selenium(IV) oxide. |
Se8(s) + 8O2(g) 8SeO2(s) |
| Reactions with halogens |
| Selenium reacts with fluorine and burns to form the selenium(VI) fluoride.
|
| Se8(s) + 24F2(g)8SeF6(l) |
| Selenium (preferably suspended in CS2) reacts with chlorine and bromine to form diselenium dichloride and diselenium dibromide, respectively.
|
| Se8(s) + 4Cl2(g)4Se2Cl2(l) |
| Se8(s) + 4Br2(l)4Se2Br2(l) |
| When carefully done, selenium reacts with fluorine at 0°C to form the selenium(IV) fluoride. Selenium also reacts under controlled conditions with the other halogens chlorine, bromine, and iodine, to form selenium(IV) tetrahalides.
|
| Se8(s) + 16F2(g)8SeF4(s) |
| Se8(s) + 16Cl2(g)8SeCl4(s) |
| Se8(s) + 16Br2(g)8SeBr4(s) |
| Se8(s) + 16I2(g)8SeI4(s) |
| Reactions with acids |
| Selenium does not react with dilute non-oxidizing acids. |
| Reduction Potentials |
| Balanced half-reaction |
E0 / V
|
SeO42- + 2H+ + 2e- SeO32- + H2O
|
+0.880 |
| SeO42- + H2O + 2e-SeO32- + 2OH- |
+0.05 |
| SeO42- + 3H+ + 2e-HSeO3- + H2O
|
+1.075 |
| SeO42- + 4H+ + 2e-H2SeO3 + H2O
|
+1.15 |
| HSeO4- + 3H+ + 2e-H2SeO3 + H2O
|
+1.090 |
| SeO32- + 6H+ + 4e-Se(s) + 3H2O
|
+0.875 |
| HSeO3- + 5H+ + 4e-Se(s) + 3H2O
|
+0.778 |
| H2SeO3 + 4H+ + 4e-Se(s) + 3H2O
|
+0.740 |
| SeO32- + 6H+ + 6e-Se2- + 3H2O
|
+0.276 |
| SeO32- + 7H+ + 6e-HSe- + 3H2O
|
+0.414 |
| HSeO3- + 6H+ + 6e-HSe- + 3H2O
|
+0.349 |
| HSeO3- + 7H+ + 6e-H2Se(g) + 3H2O
|
+0.386 |
| H2SeO3 + 6H+ + 6e-H2Se(g) + 3H2O
|
+0.360 |
| Se(s) + 2H+ + 2e-H2Se(g) |
-0.369 |
| Se(s) + 2e-Se2- |
-0.924 |
| Se(s) + H+ + 2e-HSe- |
-0.510 |
| Se(s) + 2H+ + 2e-H2Se(g) |
-0.399 |
