Redox-Reaction-Notes.pdf

Redox Reaction  DISCLAIMER “The content provided herein are created and owned by various authors and licensed to Sorting Hat Technologies Private Limited (“Company”). The Company disclaims all rights and liabilities in relation to the content. The author of the...

Redox Reaction  DISCLAIMER “The content provided herein are created and owned by various authors and licensed to Sorting Hat Technologies Private Limited (“Company”). The Company disclaims all rights and liabilities in relation to the content. The author of the content shall be solely responsible towards, without limitation, any claims, liabilities, damages or suits which may arise with respect to the same.” Introduction Chemical reactions in which reduction and oxidation takes place are known as redox reactions. In order to define oxidation and reduction, there were many concepts which are as following: Classical concept OXIDATION REDUCTION Addition of oxygen Addition of hydrogen or or Removal of hydrogen Removal of oxygen Reduction of Cl2 Oxidation of Mg e.g.   Oxidation of HCl Reduction of H2O, Oxidation of H2O Note: Above definitions failed to define oxidation and reduction in all reactions. Hence, its concept was modified later as following: OXIDATION REDUCTION Addition of electronegative element Addition of electropositive element Or or Removal of electropositive element Removal of electronegative element 1.  OXIDATION REDUCTION Oxidation of Na Oxidation of magnesium and and Reduction of Cl2 also Reduction of O2 e.g.   Oxidation and reduction of HCl Modern Concept It is an electronic concept. This concept is based upon transfer of electrons. OXIDATION REDUCTION The process in which substance The process in which substance looses some electrons. gains some electrons. 2. Oxidation of Zn and reduction of Cu2+. Oxidation of H2 and reduction of Ag+. Note: Modern concept can be used to identify oxidation and reduction only in ionic reactions. 3.  Oxidation Number The average charge per atom possessed by an element in a specie is called “oxidation number” of that element in that species (atom, molecule, ion). In a specie, the charge is developed on atoms due to di erence in electronegativity between bonded atoms or due to transfer of electrons. e.g. H2       Oxidation number of hydrogen in H2 = zero e.g. i) HCl      More electronegative         ii) HCN         Order of electronegativity   H