# What are some examples of electrochemical processes?

Dec 17, 2014

Galvanic cells are a great example of an electrochemical process.

The galvanic cell has the capability of deriving electrical energy from spontaneous REDOX reactions that take place within the cell. The cell consists of two different metals connected together by a salt bridge.

Electrons will always flow from the oxidation half cell (the anode) to the reduction half cell (the cathode) - in other words, from the more negative half reaction to the more positive half reaction.

Another great example of an electrochemical process is corrosion. A piece of bare iron will rust quickly when exposed to moisture, the corrosion rate being enhanced by an electrochemical process in which a water droplet becomes a miniature galvanic cell in contact with the metal (it oxidizes the iron).

Iron supplies electrons at the edge of the droplet to reduce oxygen from the air - the iron surface inside the droplet acts as the anode for the process

$F {e}_{\left(s\right)} \to F {e}_{\left(s\right)}^{2 +} + 2 {e}^{-}$

The electrons move through the iron to the outside of the water droplet, where

${O}_{2 \left(g\right)} + 2 {H}_{2} O \left(l\right) + 4 {e}^{-} \to 4 O H {\left(a q\right)}^{-}$

The hydroxide ions now react with the iron ions to form iron (III) hydroxide (a precipitate)

$F {e}_{\left(a q\right)}^{2 +} + 2 O {H}^{-} \left(a q\right) \to F e {\left(O H\right)}_{2} \left(s\right)$

Rust is then produced by the oxidation of the precipitate

$4 F e {\left(O H\right)}_{2} \left(s\right) + {O}_{2} \left(g\right) \to 2 F {e}_{2} {O}_{3} \cdot {H}_{2} {O}_{\left(s\right)} + 2 {H}_{2} {O}_{\left(l\right)}$

Here's a video of electrochemical machines, another example of REDOX reactions applications

and a video on corrosion