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A more reactive metal can displace a less reactive metal from a compound. For example, zinc displaces copper from copper sulfate solution: zinc atoms become zinc ions while copper ions become copper atoms. Oxidation is electron loss and reduction is electron gain. Both occur together in a redox reaction. Identify the changing species explicitly; calling an entire blue solution reduced is less precise than identifying Cu2+ gaining electrons.
Video by Cognito. The video’s own board label is retained; follow the specification reference and scope notes on this lesson for assessed content.
Viewing focus: Predict metal displacement reactions
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: What is oxidation in terms of electrons?
Loss of electrons. Remember oxidation and reduction occur together.
After watching 2: What does sacrificial zinc do when protecting iron?
Oxidises preferentially. Zinc is more reactive than iron.
What you'll be able to do
A more reactive metal can displace a less reactive metal from a compound. For example, zinc displaces copper from copper sulfate solution: zinc atoms become zinc ions while copper ions become copper atoms. Oxidation is electron loss and reduction is electron gain. Both occur together in a redox reaction. Identify the changing species explicitly; calling an entire blue solution reduced is less precise than identifying Cu2+ gaining electrons.
Metals less reactive than carbon can often be extracted from their oxides using carbon or carbon monoxide as a reducing agent. More reactive metals, including aluminium, require electrolysis of suitable molten compounds. Electrolysis needs substantial electrical energy, so ore concentration and recycling can matter economically. Some unreactive metals occur native. Phytomining and bioleaching can recover metals from low-grade sources, but rate, land use, solution handling and energy requirements affect their usefulness.
Rusting of iron needs oxygen and water. A barrier coating prevents access, while sacrificial protection connects iron to a more reactive metal that oxidises preferentially. An alloy can alter strength and corrosion behaviour because different atoms change the structure. A comparison of extraction and recycling should include resource conservation, waste, separation and processing energy. A metal’s position in the series predicts reaction tendency, but observable rate can also depend on surface coatings and conditions.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: Why cannot carbon reduce aluminium oxide in the usual school extraction process?
Molten-compound electrolysis is used.
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.