O-Level-Chemistry-Notes

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9.2 Reactivity Series
Reaction of Metals with Water
Pottasium, Sodium, and Calcium reacts with cold water to form:
M(s) + 2H2O(l) MOH(aq) + H2(g)
Metal + Water Metal Hydroxide + Hydrogen
Magnesium, Zinc, Iron reacts with steam to form:
M(s) + 2H2O(g) MO(s) + H2(g)
Metal + Water Metal Oxide + Hydrogen
Iron does not react with water
Copper and Gold have no reaction with water and steam
Reaction of Metals with Dilute Hydrochloric Acid
Pottasium, Sodium, Calcium, Magnesium, Zinc and Iron reacts with dilute
hydrochloric acid to form:
M(s) + 2HCl(aq) MCl2(aq) + H2(g)
Metal + Acid Metal Chloride + Hydrogen
Lead reacts with warm hydrochloric acid slowly
Copper and Gold have no reaction with dilute hydrochloric acid
Displacement Reactions
Displacement reaction is the displacement of ions of metal from compounds of
metals lower in reactivity series by metals higher in reactivity series.
E.g. Magnesium displaces copper(II) chloride
Mg(s) + CuCl2(aq) MgCl2(aq) + Cu(s)
For observation, we’ll see silver magnesium metal coated with brown copper metal
Displacement is due to Mg atoms transfer electrons to Cu 2+ ions forming Cu atoms.
Mg(s) → Mg 2+ (aq) + 2e -
Cu 2+ (aq) + 2e - → Cu(s)
Loss of electrons is due to it’s less reactive as less reactive metal has higher chance
of losing electrons. That’s why when Mg is placed in KCl, no reaction occurs.
Mg(s) + KCl2(aq) No reaction
E.g. Displacement from metal oxides
Metal higher in reactivity series displaces oxides of metals lower in reactivity series.
When Ca burns with Ag2O, Ca displaces Ag to produce CaO and Ag.
Ca(s) + Ag2O(s) CaO(s) + 2Ag(s)
This is called thermit reaction large amount of heat is produced.
Reaction of Metal Oxides with Carbon
The lower the position of metal in reactivity series, the easier for carbon to remove
oxygen from metal oxide by heating. At higher position, stronger heat is needed.
E.g. CuO reacts with C can be reduced by bunsen burner flame temperature
CuO(s) + C(s) Cu(s) + CO2(g)
For iron oxide to be reduced, it needs very high temperature.
Reaction of Metal Oxides with Hydrogen
The lower position of metal in reactivity series, the easier hydrogen remove oxygen
from metal oxide by heating. At higher position, stronger heat is needed.
E.g. PbO reacts with H2 can be reduced by bunsen burner flame temperature
PbO(s) + H2(g) Pb(s) + H2O(l)
Decomposition of Metal Carbonates
The lower position of metal in reactivity series, the easier hydrogen remove oxygen
from metal oxide by heating. At higher position, stronger heat is needed.
E.g. CuCO3 reacts decomposes by heat of bunsen burner flame temperature
CuCO3(s) Cu(s) + CO2(g)