REDOX REACTIONS [ELECTROCHEMISTRY] CLASS-12

ELECTROCHEMISTRY           CLASS-12

REDOX REACTIONS [ELECTRONIC CONCEPT]

• Definitions
  (i) OXIDATION :-This reaction involves loss of electron.
  (ii) REDUCTION :-This reaction involves gain of electron.
  (iii) REDOX REACTION :-This reaction involves both oxidation and reduction, i.e., in this reaction one substance(reactant) is reduced while the other substance (reactant) is oxidized.
  (iv) OXIDIZING AGENT (OXIDANT) :-The substance which gets reduced , oxidizes the other substances, is called oxidant.It gains the electron.
  (v) REDUCING AGENT (REDUCTANT) :-The substance which gets oxidized , reduces the other substances, is called reductant.It looses the electron.
  
• Example (i)
  Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)
  Or, In ionic form
  Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
  
  Zn(s) → Zn²⁺(aq) + 2e^- .....(1) [oxidation],Zn releases 2 electrons to form Zn²⁺ ion ,
  Cu²⁺(aq) + 2e^- → Cu(s) .......(2)[Reduction] Cu²⁺ ion gains 2 electrons to form Cu
  ___________________________________on adding
  Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s) .......[Redox reaction]
  OXIDANT - Cu²⁺
  REDUCTANT - Zn
  
  
• Example (ii)
  Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq)  + 2Ag(s)
  Or, In ionic form
  Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s)
  
  Cu(s) → Cu²⁺(aq) + 2e^- .....(1) [oxidation], Cu releases 2 electrons to form Cu²⁺ ion ,
  2Ag⁺(aq) + 2e^- → 2Ag(s) .......(2)[Reduction] Two Ag⁺ ions gain 2 electrons to form two Ag atoms
  _____________________________________on adding
  Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s) .......[Redox reaction]
  OXIDANT - Ag⁺
  REDUCTANT - Cu