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Electrochemical Series

The electrochemical series or the activity series is the arrangement of various electrodes in the increasing order of their standard reduction potential. The reduction potential values are seen to increase from negative to zero and positive real numbers. When arranged linearly, it would look like a number line with the positive numbers on the right side of zero and the negative numbers on the left side of zero.

What is an Electrode Potential?

An electrode when in contact with an electrolyte solution of the similar ionic nature (Example, Cu electrode in CuSO4 solution, Zn electrode in ZnSO4 solution) tends to either undergo Oxidation (loss of electrons) or reduction (gain of electrons).

Due to this oxidation or reduction, there develops a charge separation between the metal electrode and its ions in the solution creating a potential difference.

Anti-Markovnikov's Rule (Addition of HBr to an unsymmetrical alkene/alkyne)

Few reagents such as Hydrogen Halides (HX), Sulfuric Acid H2SO4, Alcohols (R-OH), Water (H2O) follow Markovnikov's Rule for the addition across the double bond of an alkene. But HBr in the presence of a peroxide shows a behavior opposite to the Markovnikov's rule, thereby termed as The Anti-Markovnikov's Rule. It was studied extensively by Morris Kharash was also known as the Kharasch effect or the Peroxide Effect. This behavior is shown only by HBr and not HF, HCl, HI even in the presence of the peroxide. In the absence of the peroxide, HBr adds as per the Markovnikov's Rule.