What is reactivity series? How does the reactivity series of metals help in predicting the relative activities of various metals?

Question

(i) What is reactivity series? How does the reactivity series of metals help in predicting the relative activities of various metals? (ii) Suggest different chemical processes used for obtaining a metal from its oxides for metals in the middle of the reactivity series and metals towards the top of the reactivity series. Support your answer with one example each.

Answer 1

(i) The arrangement of metals in the vertical column in the order of decreasing reactivity is called reactivity series or activity series. A metal placed above hydrogen in the activity series will displace hydrogen from water or acids. A metal placed at the top of the activity series would displace metal below it. Thus, a more reactive metal displaces a less reactive metal from its salt solution. 

(ii) (a) For obtaining metals that are in the middle of the reactivity series, oxides of such metals can be reduced with coke (carbon) which acts as a reducing agent. 

Example: 2Fe₂O₃ + 3C →  4Fe + 3CO₂ 

(b) For obtaining metals that are high in the reactivity series, their oxides are reduced to metals by the process of electrolysis. Example: electrolysis of sodium chloride 

At cathode: Na + e^–  → Na 

At anode: 2Cl ^– →  Cl2 + 2e ^–