Reactivity Series and Metal Extraction

The reactivity series ranks metals from most reactive to least reactive:

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Reaction with Water

Reaction with Dilute Acid

• Metals above hydrogen react with dilute acid → salt + hydrogen
• Metals below hydrogen do NOT react with dilute acid
• More reactive metals react faster (more vigorous fizzing)

A more reactive metal can displace a less reactive metal from its compound.

General Rule

A more reactive element displaces a less reactive element from its compound.

Example: Iron + Copper Sulfate

$\text{Fe}(s) + \text{CuSO}_4(aq) \rightarrow \text{FeSO}_4(aq) + \text{Cu}(s)$

Iron is more reactive than copper, so iron displaces copper. You would see:

• Iron nail turns brown/pink (copper coated on surface)
• Blue solution turns pale green (CuSO₄ → FeSO₄)

More Examples

$\text{Mg}(s) + \text{CuSO}_4(aq) \rightarrow \text{MgSO}_4(aq) + \text{Cu}(s)$ ✓

$\text{Cu}(s) + \text{MgSO}_4(aq) \rightarrow \text{No reaction}$ ✗ (Cu less reactive)

$\text{Zn}(s) + \text{FeSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Fe}(s)$ ✓

Definitions

OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain

Example: Thermite Reaction

$2\text{Al} + \text{Fe}_2\text{O}_3 \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}$

• Aluminium is oxidised (gains oxygen, loses electrons)
• Iron oxide is reduced (loses oxygen, iron gains electrons)
• This is a redox reaction (both oxidation and reduction occur)

In Displacement Reactions

$\text{Fe} + \text{CuSO}_4 \rightarrow \text{FeSO}_4 + \text{Cu}$

• Fe → Fe²⁺ + 2e⁻ (iron is oxidised — loses electrons)
• Cu²⁺ + 2e⁻ → Cu (copper is reduced — gains electrons)

The more reactive metal is always oxidised; the less reactive metal ion is reduced.

The method used to extract a metal from its ore depends on the metal's position in the reactivity series.

Metals Above Carbon: Electrolysis

Very reactive metals (K, Na, Ca, Mg, Al) cannot be reduced by carbon — they are more reactive than carbon. They must be extracted using electrolysis.

Example: Aluminium extraction from bauxite ore (see Electrolysis topic).

Metals Below Carbon: Reduction with Carbon

Less reactive metals (Zn, Fe, Sn, Pb) can be extracted by heating their oxide with carbon. Carbon is more reactive and displaces the metal.

$\text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO}$

$\text{Fe}_2\text{O}_3 + 3\text{C} \rightarrow 2\text{Fe} + 3\text{CO}$

Or using carbon monoxide: $\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2$

This is how iron is extracted in a blast furnace.

Unreactive Metals: Found Native

Gold, silver, and platinum are so unreactive they are found as pure elements in nature ("native" metals).

Recycling is important because:

• Saves energy (much less than extraction from ore)
• Conserves finite resources (metal ores will run out)
• Reduces landfill waste
• Reduces environmental damage from mining
• Reduces CO₂ emissions from extraction processes

• Memorise the reactivity series order — it appears in almost every chemistry paper
• In displacement reactions, identify which metal is more reactive → it displaces the other
• Use OIL RIG to identify oxidation and reduction
• For extraction methods, the key question is: is the metal above or below carbon?
• Always state both oxidation AND reduction in a redox reaction

• The reactivity series ranks metals from most to least reactive
• More reactive metals displace less reactive metals from compounds
• Oxidation = loss of electrons / gain of oxygen; Reduction = gain of electrons / loss of oxygen
• Metals above carbon → extracted by electrolysis
• Metals below carbon → extracted by reduction with carbon
• OIL RIG: Oxidation Is Loss, Reduction Is Gain