Why are oxidizing agents acidified?

1 Answer
anor277
Dec 23, 2016

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.

Related questions
See all questions in Oxidation and Reduction Reactions
Impact of this question
11227 views around the world
You can reuse this answer
Creative Commons License