Editing Redox (section)

===Metal displacement===

[[File:Galvanic cell with no cation flow.svg|thumb|upright=1.6|A redox reaction is the force behind an [[electrochemical cell]] like the [[Galvanic cell]] pictured. The battery is made out of a zinc electrode in a ZnSO<sub>4</sub> solution connected with a wire and a porous disk to a copper electrode in a CuSO<sub>4</sub> solution.]]

In this type of reaction, a [[metal]] atom in a compound or solution is replaced by an atom of another metal. For example, [[copper]] is deposited when [[zinc]] metal is placed in a [[copper(II) sulfate]] solution:

:{{chem2|Zn (s) + CuSO4 (aq) -> ZnSO4 (aq) + Cu (s)}}

In the above reaction, zinc metal displaces the copper(II) ion from the copper sulfate solution, thus liberating free copper metal. The reaction is spontaneous and releases 213 kJ per 65 g of zinc.

The ionic equation for this reaction is:

:{{chem2|Zn + Cu(2+) -> Zn(2+) + Cu}}

As two [[half-reaction]]s, it is seen that the zinc is oxidized:

:{{chem2|Zn -> Zn(2+) + 2 e(-)}}

And the copper is reduced:

:{{chem2|Cu(2+) + 2 e(-) -> Cu}}