Question

(a) What is reactivity series of metals? What can you say about the reactivity of metals which are placed:
(i) in the middle of reactivity series?
(ii) towards the bottom of reactivity series?
(iii) towards the top of reactivity series?
(b) A metal is placed in the middle of reactivity series. Suggest a chemical process to obtain this metal from its oxide. Support your answer with one example.
​(c) A metal is placed towards the top of the reactivity series. Suggest a chemical process to obtain this metal from its oxide. Support your answer with one example.

Answer 1

(a) When elements are arranged in the increasing order of reduction potential with respect to hydrogen, the series obtained is called the reactivity series.
(i) Hydrogen is placed in the middle of the series. It can lose an electron to form a positive ion and combine with non-metals which are electron attracting species.
(ii) In the bottom of the series elements are very less reactive they are even available in their elemental state. For eg. gold, silver, etc.
(iii) Elements at the top of the table are very reactive, they have a strong tendency to lose their electrons and form bonds.

(b) For obtaining metal that is in the middle of reactivity series, oxide of such metal can be reduced with coke which acts as a reducing agent.

$2{\mathrm{Fe}}_2{\mathrm{O}}_3+3\mathrm{C}\to 4\mathrm{Fe}+3{\mathrm{CO}}_2$

(c) For obtaining metal that is high in the reactivity series their oxide is reduced to metal by the process of electrolysis.
Electrolysis of sodium chloride:

$$\begin{gathered} \mathrm{At}\mathrm{cathode}:\mathrm{Na}\to {\mathrm{Na}}^{+}+{\mathrm{e}}^{-} \\ \mathrm{At}\mathrm{anode}:\mathrm{Cl}+{\mathrm{e}}^{-}\to {\mathrm{Cl}}^{-} \end{gathered}$$