Metals Equations

This page collects all metals equations for 0620, organised by reaction type. Use alongside the reactivity series and extraction of metals.

The reactivity series

Most reactive to least reactive:

K > Na > Ca > Mg > Al > (C) > Zn > Fe > (H) > Cu > Ag > Au

Carbon and hydrogen are included as reference points for extraction method and acid reactions.

Metal + Water reactions

Metal	Equation	Observations
Potassium	2K + 2H2O -> 2KOH + H2	Burns with lilac flame, very vigorous
Sodium	2Na + 2H2O -> 2NaOH + H2	Melts, moves rapidly, vigorous fizzing
Lithium	2Li + 2H2O -> 2LiOH + H2	Gentle fizzing, floats
Calcium	Ca + 2H2O -> Ca(OH)2 + H2	Steady fizzing, milky solution
Magnesium	Mg + 2H2O -> Mg(OH)2 + H2	Very slow with cold water

Metals below Mg: no reaction with cold water.

Metal + Steam reactions

Metal	Equation	Observations
Magnesium	Mg + H2O -> MgO + H2	Burns with white glow
Zinc	Zn + H2O -> ZnO + H2	Slow, zinc glows
Iron	3Fe + 4H2O -> Fe3O4 + 4H2	Iron glows red, reversible

Metals below iron do not react with steam.

Metal + Dilute acid reactions

Metal	Equation	Observations
Magnesium + HCl	Mg + 2HCl -> MgCl2 + H2	Very vigorous effervescence
Zinc + HCl	Zn + 2HCl -> ZnCl2 + H2	Steady effervescence
Iron + HCl	Fe + 2HCl -> FeCl2 + H2	Slow effervescence, pale green solution
Magnesium + H2SO4	Mg + H2SO4 -> MgSO4 + H2	Very vigorous effervescence
Zinc + H2SO4	Zn + H2SO4 -> ZnSO4 + H2	Steady effervescence
Iron + H2SO4	Fe + H2SO4 -> FeSO4 + H2	Slow, pale green solution

Cu, Ag, Au: no reaction with dilute acids (below hydrogen in the reactivity series).

Displacement reactions

A more reactive metal displaces a less reactive metal from its salt solution.

Equation	Observations
Mg + CuSO4 -> MgSO4 + Cu	Blue solution decolourises, brown copper deposited
Zn + CuSO4 -> ZnSO4 + Cu	Blue solution decolourises, brown copper deposited
Fe + CuSO4 -> FeSO4 + Cu	Blue fades to pale green, brown copper deposited
Mg + ZnSO4 -> MgSO4 + Zn	Colourless solution remains, grey zinc deposited
Mg + FeSO4 -> MgSO4 + Fe	Pale green fades to colourless, grey iron deposited

Cu + MgSO4: no reaction (copper is less reactive than magnesium).

See displacement reactions.

Extraction of metals

By carbon reduction (metals below carbon)

Metal oxide	Equation
Iron(III) oxide	Fe2O3 + 3CO -> 2Fe + 3CO2 (blast furnace)
Zinc oxide	ZnO + C -> Zn + CO
Lead(II) oxide	2PbO + C -> 2Pb + CO2
Copper(II) oxide	2CuO + C -> 2Cu + CO2

By electrolysis (metals above carbon)

Metal	Source	Cathode half-equation
Aluminium	Al2O3 in cryolite	Al3+ + 3e- -> Al
Sodium	Molten NaCl	Na+ + e- -> Na
Magnesium	Molten MgCl2	Mg2+ + 2e- -> Mg

Thermite reaction

2Al + Fe2O3 -> Al2O3 + 2Fe

Aluminium displaces iron because Al is more reactive. Highly exothermic — used for welding railway tracks.

Metal oxide + Hydrogen (reduction)

CuO + H2 -> Cu + H2O (black to pink-brown)

Fe2O3 + 3H2 -> 2Fe + 3H2O

H2 acts as a reducing agent.

Rusting

4Fe + 3O2 + 6H2O -> 4Fe(OH)3 -> 2Fe2O3.3H2O

Both oxygen and water are needed. See rusting and prevention.

A piece of magnesium is placed in copper(II) sulfate solution. Write the equation and describe what you would see. [3 marks]

• Mg + CuSO4 -> MgSO4 + Cu [1]
• The blue colour fades / solution becomes colourless [1]
• Brown/pink-brown solid (copper) is deposited on the magnesium [1]

Explain why aluminium is extracted by electrolysis but iron is extracted in a blast furnace. [3 marks]

• Aluminium is above carbon in the reactivity series, so carbon cannot reduce it [1]
• Iron is below carbon in the reactivity series, so carbon (as coke/CO) can reduce iron oxide [1]
• Electrolysis is more expensive due to the large amounts of electricity needed, so it is only used when necessary [1]