Displacement reactions
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Explainer Video
Summary
Displacement reactions
In a nutshell
Displacement reactions involve a more reactive metal displacing a less reactive metal present in a compound. In this lesson you will learn about why displacement reactions occur as well some examples.
Displacement
Displacement reactions involve a more reactive metal and a compound which contains a less reactive metal.
When a reactive metal comes into contact with the compound it displaces (pushes out and takes the place of) the less reactive metal.
The less reactive metal that is displaced is not bound to other elements and therefore exits as a pure element.
Reactivity
Metals have different reactivities: some are reactive, some are are unreactive and some are completely inert.
Examples
Magnesium is a reactive metal. When magnesium is heated it readily reacts with oxygen in the air.
Platinium is inert and will not react with oxygen even at high temperatures, therefore platinium is a good substance to use in fine jewellery and surgical tools.
Reactivity series
The reactivity series shows metals in order of reactivity, with the most reactive at the top and the least reactive at the bottom.
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Reactions
Displacement reactions can be carried out to determine the reactivity of metals. This involves placing a metal into a salt solution and observing what happens.
A change is colour indicates that a displacement reaction has occurred.
Example
Copper sulfate is a blue solution but when zinc is added to it, the solution turns colourless. This is because a displacement reaction occurs and zinc sulfate, a colourless compound, forms.
Example
When copper is added to a solution of magnesium chloride, no reaction occurs and no change is observed. This is because copper is less reactive than magnesium and cannot displace it from its salt.
FAQs - Frequently Asked Questions
What is a metal displacement reaction?
When a reactive metal comes into contact with a salt compound it displaces (pushes out and takes the place of) the less reactive metal present.
What is the difference between an unreactive chemical and a reactive chemical?
A reactive chemical easily participates in reactions. An unreactive chemical participates in reactions very slowly.
How can you determine the reactivity of metals?
Displacement reactions can be carried out to determine reactivity of metals. This involves placing a metal into a salt solution and observing what happens. A change in colour indicates that a displacement reaction has occurred.