Page 5 - Pharmaceutical Analytical Chemistry II - Pharm D Clinical- 07-PA202
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Electrical Conduction in an electrochemical
                                   cell

Electricity is conducted by:

    • Electrons flow through the external conductor (wire)

    • Within the two solutions; movement of anions and cations between

         electrode compartments across the liquid junction. Anions move

         towards anode and cations move towards cathode.

Classification of Electrochemical cell

Based on the SPONTANEITGYaolfvthaenielcectCroeclhlemical reactions:

  Cells store electrical energy "e.g. Batteries"

  The Redox reactions at the electrodes tend to proceed spontaneously

 Chemical change (Redox reaction) → Electric current

  Electrons flow from the anode to the cathode via an external conductor,
  therefore, the anode is negative electrode and the cathode is positive
  one

                              Anode Cu metal electrode /

                              CuSO4

                              Copper "half-reaction"

                              Oxidation

                              Cu(s)         Cu2+ (aq) + 2e-

                              Cu2+ goes into aqueous solution

                              Decrease in the mass of Cu

                              electrode

                              Cathode Ag metal electrode/

                              AgNO3

                              Silver "half-reaction"

                              Reduction

                              Ag+(aq) + e-  Ag(s)

                              Uncharged Ag atom deposits on

                              the silver electrode, increasing its

                              mass

Cell reaction Spontaneous

Cu(s) + 2Ag+(aq)  Cu2+ (aq) + 2Ag(s)

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