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 sulphateIron sulphate + Copper

These reactions take place due to differences in 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.

Looking at our 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).

Let’s look at an example that wouldn’t work:

Iron + Magnesium sulphate

Fe + MgSO4

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