Ye olde' aquatic acidic environments. (1 Viewer)

[Deedum]

With the use of a relevant half equation, explain how acidic environments accelerate the corrosion of a non-passevating metal.

Half equation: 2H+ + 1/2 O2 + 2e- <---> H20


I understand it all, except how the H+ ions get to be by themselves Help please?

 

[xiao1985]

you may acidify the environment by addition of acids such as nitric acid:

H+ + NO3-

you will have nitrates flowing around, they however, will not participate in the redox reaction here.

 

[Forbidden.]

With the use of a relevant half equation, explain how acidic environments accelerate the corrosion of a non-passevating metal.

Half equation: 2H+ + 1/2 O2 + 2e- <---> H20


I understand it all, except how the H+ ions get to be by themselves Help please?

Reduction Half-Reaction:
0.5O₂(g) + 2H⁺ + 2e^- <--> H₂O

Oxidation Half-Reaction:
Fe(s) --> Fe²⁺ + 2e^-

Overall reaction:
0.5O₂(g) + 2H⁺ + Fe(s) <--> Fe²⁺ + H₂O

If there is an excess of H⁺ i.e. there is an acidic environment you will force the reaction to the right, therefore accelerating the formation of rust.

The H⁺ get to be by themselves as they participate in the reaction rather than go into water solvent as H₃O⁺ (hydronium) ions in solution.