Question

Why are oxidizing agents acidified?

Answer 1

Usually because oxidation reactions tend to specify acidic conditions.

Explanation:

And basic conditions tend to lead to the precipitation of insoluble metal hydroxides.

Metal oxidants, say permanganate, `MnO_4^-`, or dichromate, `Cr_2O_7^(2-)` tend to be deployed in acidic media:

`MnO_4^(-) +8H^+ + 5e^(-) rarr Mn^(2+) + 4H_2O`

`Cr_2O_7^(2-) +14H^+ + 6e^(-) rarr 2Cr^(3+) + 7H_2O`

So we use `H^+` or `H_3O^+` in the reaction to represent the actual acidic condtions of reaction. Had the reaction been conducted in A BASIC medium, heavy metal oxides and hydroxides would precipitate out pdq.

If a redox reaction is specified to be in a BASIC medium, it is often easiest to balance the redox reaction in acidic conditions using `H^+`, and then add `HO^-` ion to each side of the reaction.

For instance, aluminum metal can be oxidized up to aluminate ion, `Al(OH)_4^-` in strong base. We could represent this as normal:

`AlrarrAl^(3+) + 3e^-`, but then we could add `4xxHO^-` to BOTH sides of the reaction:

`Al +4HO^(-) rarr[Al(OH)_4]^(-) + 3e^-`

Charge and mass are balanced in this reaction as required.