Displacement Reactions

In a displacement reaction, an element that is more reactive pushes out (displaces) an element that is less reactive.

Below is an example of a displacement reaction between iron and copper sulphate.

In this scenario, we can say that the iron (Fe) displaced copper (Cu), as it has swapped positions with copper. Iron is now bonded to the sulphate (SO4) in the solution as iron sulphate (FeSO4) and the metal in the solution is now copper (on its own).

The word equation for this reaction is:

Iron + Copper sulphate ⮕ Iron sulphate + Copper

These reactions take place due to reactivity. Let us take a look at the reactivity series:

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For a displacement reaction to take place, the element on its own must be more reactive than the element that is in the compound.

As you can see, iron is more reactive than copper.

Looking at our earlier earlier example, iron (which is on its own) is more reactive than copper (which is in the solution). This is why the iron replaces the copper and we end up with iron sulphate (FeSO4).

Lets look at an example that wouldn’t work:

iron + Magnesium sulphate ⮕

Fe + MgSO4

As aluminium is more reactive than iron, iron will not displace the magnesium and the reaction will not take place.