The Reactivity Series of Metals and Its Application

The Reactivity Series of Metals and Its Application
1. Metal form metal oxides when burnt in air (excess).
Metal + Oxygen –> Metal oxide
Example: 2Zn(s) + O₂(g) –> 2ZnO(s)
2. The more reactive a metal is, the more vigorously it burns in oxygen.
Reactivity of Metals
K, Na, Ca, Mg, Al, Zn, Fe, Sn, Pb, Cu, Hg, Ag, Au
<——– increase in reactivity of metals
3. Reactivity of Metals with Oxygen.

Metal	Observation	Inference	Equation
Magnesium (Mg)	Burns vigorously with a very brilliant white flame.The residue is white when hot and cold.	The reactivity of Mg towards O2 is very high.Magnesium oxide is formed.	2Mg(s) + O2(g)–> 2MgO(s)
Zinc (Zn)	Burns quickly with a bright flame.The residue is yellow when hot and white when cold.	The reactivity of Zn towards O2 is high.Zinc oxide is formed.	2Zn(s) + O2(g)–> 2ZnO(s)
Iron (Fe)	Glows very brightly.The residue is reddish-brown when hot and cold.	The reactivity of Fe towards O2 is medium.Iron(III) oxide is formed.	2Fe(s) + O2(g)–> 2Fe2O3(s)
Lead (Pb)	Glows brightly.The residue is brown when hot and yellow when cold.	The reactivity of Pb towards O2 is low.Lead(II) oxide is formed.	2Pb(s) + O2(g)–> 2PbO(s)
Copper (Cu)	Glows faintly.The residue is black when hot and cold.	The reactivity of Cu towards O2 is very low.Copper(II) oxide is formed.	2Cu(s) + O2(g)–> 2CuO(s)

• Glass wool – prevents metal powder mixes with potassium manganate(VII)
• Solid potassium manganate(VII) – liberates oxygen gas when it is heated / decomposed.

2KMnO₄(s) —-> K₂MnO₄(s) + MnO₂(s) + O₂(g)
heat

• Other than potassium manganate(VII),

- solid potassium chlorate(V) with manganese(IV) oxide as a catalyst.
MnO₂
2KClO₃(s) —-> KCl(s) + 3O₂(g)
heat
- solid potassium nitrate
2KNO₃(s) —-> KNO₂(s) + O₂(g)
heat
4. Position of Carbon in the Reactivity Series of Metals
Reactivity Series
K, Na, Ca, Mg, Al, C, Zn, Fe, Sn, Pb, Cu, Hg, Ag, Au
<——– increase in reactivity
a) Metal + Carbon dioxide –> Metal oxide + Carbon
Any metal above carbon in the reactivity series can displace oxygen from carbon dioxide.
Example: 2Mg(s) + CO₂(g) –> 2MgO(s) + C(s)
Mg: Reducing agent
CO₂: Oxidising agent
MgO: White residue
C: Black spots
–> Therefore, magnesium is more reactive than carbon.
(If the metal is less reactive than carbon, the metal is unable to remove oxygen from carbon dioxide.)
b) Carbon + Metal oxide –> Carbon dioxide + Metal
Any metal below carbon in the reactivity series can displace carbon from its oxide.
Example: C(s) + 2ZnO(s) –> 2Zn(s) + CO₂(g)
C: Reducing agent
ZnO: Oxidising agent
Zn: Grey residue
–> Therefore, zinc is less reactive than carbon.
(If carbon is less reactive than the metal, the carbon is unable to remove oxygen from metal oxide.)