The reactivity series and extracting metals
Metals can be put in order of how readily they react. That order predicts which metal wins a displacement reaction, how fiercely a metal reacts with acid, and how a metal has to be extracted from its ore.
Part 1 of 3: Learn it
In short
- More reactive metals lose electrons more easily to form positive ions.
- A more reactive metal pushes a less reactive one out of its compound (displacement).
- Metals below carbon are extracted by heating the ore with carbon; metals above carbon need electrolysis.
Where this is in your specification
Spec points: AQA 4.4.1.1 to 4.4.1.4 and 4.4.2.1 (Combined Trilogy 5.4.1 and 5.4.2.1), Edexcel Topics 3 and 4, OCR C3.3
| Board | Topic: Chemical changes: reactivity, acids and electrolysis |
|---|---|
| AQA 8462 | 4.4 (8462); 5.4 (8464) |
| Edexcel 1CH0 | Topics 3 and 4 |
| OCR J248 | C3.2 to C3.4 |
| Eduqas C410 | 6, 7 |
| Cambridge IGCSE 0620 | 4.1, 6.4, 7.1 to 7.3, 9.1 to 9.6 |
| National 5 C813 75 | 1(d) Acids and bases; 3(a) Metals |
The series
| Metal | With water | With dilute acid | Extraction |
|---|---|---|---|
| Potassium, sodium, lithium, calcium | fizz, sodium and potassium violently | dangerously fast | electrolysis |
| Magnesium, aluminium | very slow | fizz quickly | electrolysis |
| Zinc, iron | very slow or none | fizz slowly | heat with carbon |
| Copper, silver, gold | none | none | copper by carbon; gold is found as the metal |
Carbon and hydrogen are not metals but are placed in the series for comparison: carbon between aluminium and zinc, hydrogen between iron and copper.
A metal that reacts with an acid makes a salt and hydrogen. For example, zinc and sulfuric acid give zinc sulfate and hydrogen gas. Metals below hydrogen do not react with dilute acids.
Displacement
Put a metal into a solution of another metal's salt. If the added metal is higher in the series, it takes the other metal's place. Zinc dropped into blue copper sulfate solution ends up as colourless zinc sulfate solution, with copper metal coating the zinc. If the added metal is lower, nothing happens.
Oxidation and reduction
- Oxidation is gain of oxygen; reduction is loss of oxygen.
- In terms of electrons (Higher): oxidation is loss, reduction is gain. Remember OIL RIG.
- In zinc + copper ions, Zn → Zn²⁺ + 2e⁻ is oxidation and Cu²⁺ + 2e⁻ → Cu is reduction.
Extracting metals
Most metals are found as compounds in ores. Carbon is more reactive than iron, so heating iron oxide with carbon removes the oxygen: the iron oxide is reduced. Aluminium is more reactive than carbon, so it must be extracted by electrolysis, which uses a lot of energy and costs more.
Will copper react with magnesium sulfate solution?
Show the answer
No. Copper is less reactive than magnesium, so it cannot displace it.
Part 2 of 3: See it worked
Worked examples
Example 1
Balance the equation for reducing iron(III) oxide with carbon: Fe₂O₃ + C → Fe + CO₂.
- Oxygen: 3 in Fe₂O₃ and 2 in CO₂, so use 2Fe₂O₃ and 3CO₂ (6 each)
- Iron: 2 × 2 = 4, so 4Fe
- Carbon: 3CO₂ needs 3C
Answer: 2Fe₂O₃ + 3C → 4Fe + 3CO₂.
Example 2
Iron filings are added to copper sulfate solution. Predict what you see and name the products.
- Iron is above copper in the reactivity series
- So iron displaces copper, giving iron sulfate solution and copper metal
- The blue colour fades and a pink-brown solid forms
Answer: A reaction happens, making iron sulfate and copper.
Common mistakes
- Predicting a displacement reaction when the solid metal is less reactive than the one in solution.
- Saying the metal oxide is oxidised during extraction with carbon. It loses oxygen, so it is reduced.
- Mixing up the electron definitions: oxidation is loss of electrons.
- Thinking all metals react with dilute acid. Copper, silver and gold do not.
Why is aluminium extracted by electrolysis and not by heating with carbon?
Show the answer
Aluminium is more reactive than carbon, so carbon cannot remove the oxygen from aluminium oxide.
Part 3 of 3: Test yourself
Check yourself
Answer each one in your head or on paper first, then open it to check.
Will copper react with magnesium sulfate solution?
No. Copper is less reactive than magnesium, so it cannot displace it.
Why is aluminium extracted by electrolysis and not by heating with carbon?
Aluminium is more reactive than carbon, so carbon cannot remove the oxygen from aluminium oxide.
Name the products when zinc reacts with dilute hydrochloric acid.
Zinc chloride and hydrogen.
Jobs that use this
Each link opens the job profile on the National Careers Service (England). In the rest of the UK: My World of Work (Scotland), Careers Wales, nidirect careers (Northern Ireland).
Diese Lernzettel sind auf Englisch, weil sie britischen Prüfungslehrplänen folgen.
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