| Reactions of Phosphorus |
 Reactions with water |
| White phosphorus glows in the dark when exposed to damp air in a process known as chemiluminescence. |
| Reactions with air |
| White phosphorus must be handled with great care. It spontanteously ignites in air at about room temperature to form "phosphorus
pentoxide" - actually tetraphosphorus decaoxide, P4O10.
|
P4(s) + 5O2(g) P4O10(s) |
| Under careful control (75% O2, 25% N2, 50°C, 90 mm Hg), a mixture is formed, one of the products within which is "phosphorus trioxide" - actually tetraphosphorus
hexaoxide, P4O6.
|
| P4(s) + 3O2(g)P4O6(s) |
| Reactions with halogens |
| White phosphorus, P4, reacts vigorously with all the halogens at room temeperature to form phosphorus(III) trihalides.
|
| P4(s) + 6F2(g)4PF3(g) |
| P4(s) + 6Cl2(g)4PCl3(g) |
| P4(s) + 6Br2(g)4PBr3(g) |
| P4(s) + 6I2(g)4PI3(g) |
| White phosphorus reacts with iodine in carbon disulphide (CS2) to form phosphorus(II) iodide. The same compound is formed in the reaction between red phosphorus and iodine at 180°C.
|
| P4(s) + 4I2(g)2P2I4(g) |
| Reactions with acids |
| Phosphorus does not react with dilute non-oxidizing acids. |
| Reduction Potentials |
| Balanced half-reaction |
E0 / V
|
PO43- + 3H+ + 2e- HPO32- + H2O
|
+0.121 |
| HPO42- + 2H+ + 2e-HPO32- + H2O
|
-0.234 |
| H2PO4- + H+ + 2e-HPO32- + H2O
|
-0.447 |
| H2PO4- + 2H+ + 2e-H2PO3- + H2O
|
-0.260 |
| H3PO4 + H+ + 2e-H2PO3- + H2O
|
-0.329 |
| H3PO4 + 2H+ + 2e-H3PO3 + H2O
|
-0.276 |
| PO43- + 8H+ + 5e-P(red) + 4H2O
|
-0.128 |
| PO43- + 8H+ + 5e-P(white) + 4H2O
|
-0.156 |
| HPO42- + 7H+ + 5e-P(red) + 4H2O
|
-0.288 |
| HPO42- + 7H+ + 5e-P(white) + 4H2O
|
-0.316 |
| H2PO4- + 6H+ + 5e-P(red) + 4H2O
|
-0.358 |
| H2PO4- + 6H+ + 5e-P(white) + 4H2O
|
-0.386 |
| H3PO4 + 5H+ + 5e-P(red) + 4H2O
|
-0.383 |
| H3PO4 + 5H+ + 5e-P(white) + 4H2O
|
-0.411 |
| PO43- + 11H+ + 8e-PH3(g) + 4H2O
|
-0.123 |
| HPO42- + 10H+ + 8e-PH3(g) + 4H2O
|
-0.212 |
| H2PO4- + 9H+ + 8e-PH3(g) + 4H2O
|
-0.265 |
| H3PO4 + 8H+ + 8e-PH3(g)) + 4H2O
|
-0.281 |
| H3PO3 + 2H+ + 2e-H3PO2 + H2O
|
-0.499 |
| HPO32- + 5H+ + 3e-P(red) + 3H2O
|
-0.298 |
| HPO32- + 5H+ + 3e-P(white) + 3H2O
|
-0.346 |
| H2PO3- + 4H+ + 3e-P(red) + 3H2O
|
-0.419 |
| H2PO3- + 4H+ + 3e-P(white) + 3H2O
|
-0.467 |
| H3PO3 + 3H+ + 3e-P(red) + 3H2O
|
-0.454 |
| H3PO3 + 3H+ + 3e-P(white) + 3H2O
|
-0.502 |
| H4P2O6 + 2H+ + 2e-2H3PO3 |
+0.38 |
| 2H3PO4 + 2H+ + 2e-H4P2O6 + 2H2O
|
-0.94 |
| P(red) + 3H+ + 3e-PH3(g) |
-0.111 |
| P(white) + 3H+ + 3e-PH3(g) |
-0.063 |
