Is there any difference between reactivity series and electrochemical series or they are same?

Hi

In introductory chemistry, the reactivity series or activity series is an empirical series of metals, in order of "reactivity" from highest to lowest . It is used to summarize information about the reactions of metals with acids and water, single displacement reactions and the extraction of metals from their ores.

Going from bottom to top, the metals:

• increase in reactivity;
• lose electrons more readily to form positive ions;
• corrode or tarnish more readily;
• require more energy (and different methods) to be separated from their ores;
• become stronger reducing agents.

The reactivity series is sometimes quoted in the strict reverse order of standard electrode potentials, when it is also known as the "electrochemical series":

Li > K > Sr > Ca > Na > Mg > Al > Zn > Cr > Fe > Cd > Co > Ni > Sn > Pb > H > Cu > Ag > Hg > Pt > Au

The positions of lithium and sodium are changed on such a series: gold and platinum are also inverted, although this has little practical significance as both metals are highly unreactive.

Standard electrode potentials offer a quantitative measure of the power of a reducing agent, rather than the qualitative considerations of other reactivity series. However, they are only valid for standard conditions: in particular, they only apply to reactions in aqueous solution. Even with this proviso, the electrode potentials of lithium and sodium – and hence their positions in the electrochemical series – appear anomalous. The order of reactivity, as shown by the vigour of the reaction with water or the speed at which the metal surface tarnishes in air, appears to be

potassium > sodium > lithium > alkaline earth metals,

the same as the reverse order of the (gas-phase) ionisation energies. This is borne out by the extraction of metallic lithium by the electrolysis of a eutectic mixture of lithium chloride and potassium chloride: lithium metal is formed at the cathode, not potassium.