In redox reactions an oxidant (oxidizing agent) and a reductant (reducing agent) react by electron transfer.
In aqueous solution, sulfuric acid is a weak oxidant and does not react with ANY of the halides.
In the absence of water concentrated sulfuric acid acts as an oxidant.
As shown concentrated H2SO4 is stronger oxidant than Br2 and I2 but weaker than F2 and Cl2.
Halide ions are examples of reductants (electron donors).
Halides react with oxidants to give the corresponding halogen
IF the oxidant is stronger than the product halogen (see below, Br2 stronger than I2). Example oxidant:
Br2 + 2I–
I2 + 2Br–
How does the oxidising strength of sulfuric acid compare to that of the halogens? Halides react with oxidants to give the corresponding halogen
IF the oxidant is stronger than the product halogen (see below, Br2 stronger than I2). Example oxidant:
Br2 + 2I–
I2 + 2Br–In aqueous solution, sulfuric acid is a weak oxidant and does not react with ANY of the halides.
In the absence of water concentrated sulfuric acid acts as an oxidant.
As shown concentrated H2SO4 is stronger oxidant than Br2 and I2 but weaker than F2 and Cl2.
| Oxidant strength | oxidants | reductants | Reductant strength |
very strong moderate | F2 (fluorine) | F– (fluoride) | very weak moderate |
| Cl2 (chlorine) | Cl– (chloride) | ||
| conc H2SO4 | |||
| Br2 (bromine) | Br– (bromide) | ||
| I2 (iodine) | I– (iodide) |