AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
A more reactive metal can displace a less reactive metal from a compound.
Full specification wording
The reactivity series: A more reactive metal can displace a less reactive metal from a compound.
Displacement occurs when a more reactive metal takes the place of a less reactive metal in a compound.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 6 of 7
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Displacement occurs when a more reactive metal takes the place of a less reactive metal in a compound. For example, magnesium placed in copper sulfate solution displaces copper, because magnesium is above copper in the reactivity series. The magnesium atoms lose electrons to form Mg²⁺ ions, which enter the solution, while Cu²⁺ ions gain electrons to form copper atoms. The blue colour fades and a pink-brown solid appears. The reverse, copper in magnesium sulfate solution, gives no reaction because copper is less reactive. Displacement is therefore evidence for the order of reactivity and can be used to deduce an order from experimental results.
What earns the marks
- A more reactive metal displaces a less reactive metal from its compound.
- In the reaction, the more reactive metal forms positive ions that enter the solution.
- The less reactive metal is displaced and appears as a solid.
- Observations such as colour change, solid deposit or temperature change provide evidence of displacement.
- No reaction occurs when the metal is less reactive than the metal in the compound.
Common mistakes and how to put them right
Saying the more reactive metal is displaced.
Put it right by stating that the more reactive metal displaces the less reactive metal.
Writing that copper displaces magnesium from magnesium sulfate.
Put it right by stating that copper is less reactive and no reaction occurs.
Ignoring the ionic explanation.
Put it right by stating that the more reactive metal forms positive ions and the less reactive metal ion gains electrons.
Exam tips
- Name both the metal and the compound when describing a displacement reaction.
- Include the ionic equation or ion symbols to show which species gains and loses electrons.
- Use the result of a displacement experiment to justify a position in the reactivity series.
Try the lesson
The start of the The reactivity series: A more reactive metal can displace a less reactive metal from a compound. lesson, made from checked teaching notes for this specification point.
Have a go first
A piece of magnesium is placed in copper sulfate solution. What is observed?
Listen
Displacement occurs when a more reactive metal takes the place of a less reactive metal in a compound. For example, magnesium placed in copper sulfate solution displaces copper, because magnesium is above copper in the reactivity series. The magnesium atoms lose electrons to form Mg²⁺ ions, which enter the solution, while Cu²⁺ ions gain electrons to form copper atoms. The blue colour fades and a pink-brown solid appears. The reverse, copper in magnesium sulfate solution, gives no reaction because copper is less reactive. Displacement is therefore evidence for the order of reactivity and can be used to deduce an order from experimental results. A strong answer earns marks for these points. A more reactive metal displaces a less reactive metal from its compound. In the reaction, the more reactive metal forms positive ions that enter the solution. The less reactive metal is displaced and appears as a solid. Observations such as colour change, solid deposit or temperature change provide evidence of displacement. A common slip: Saying the more reactive metal is displaced. Instead, stating that the more reactive metal displaces the less reactive metal. Exam tip: Name both the metal and the compound when describing a displacement reaction.
Key words
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Displacement reactions
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Reactivity series
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Ionic equations
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Experimental evidence
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See every definition
- Displacement reactions
- A more reactive metal takes the place of a less reactive metal in a compound.
- Reactivity series
- An order of reactivity that can be deduced from displacement observations and experimental results.
- Ionic equations
- Show which species gains and loses electrons, with the more reactive metal forming positive ions that enter the solution.
- Experimental evidence
- Observations such as colour change, solid deposit or temperature change that provide evidence of displacement.
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