• Galvanic cell = battery → provide power                                                                                                               
  • REDOX reactions can be used to convert chemical energy into electrical energy                                                       

Can use two half reactions and cause electrons to flow through a wire (electricity)

  • With this set up (→), the system will start but then stop immediately BCUZ will have a build up of positive change in the left half cell and buildup of negative charge in right half cell

                     For a circuit to flow, need a constant flow of charge


  • Salt bridge fixes the above problem → allows spectator (not part of redox reaction) ion migration

                ○ Spectator ions wont be oxidized or reduced; Cations → cathode; anions → anode

  • In the Anode solid atoms of zinc are being converted into aqueous zinc (oxidation) & deposited into the solution→ zinc bar is losing mass over time

             ○ Justify: Oxidation is taking place (electrons are being released)

  • In the Cathode aqueous copper ions are being converted into solid copper (reduction) and are deposited into the cathode → the mass of the electrode will increase over time

            ○ Justify: Reduction is taking place (electrons are being consumed)

  • What if species involved in galvanic cell reaction are not solid (liquid, aqueous, or gas)?

        A solid electrode is still needed → usually platinum or graphite are used bcuz they are conductive but mostly unreactive

  • Electrode & half-cell questions:

            ○ Remove an electrode → voltage becomes zero and remains there

           ○ Changing the mass of a solid electrode will have no change on the E° b/c chemical reaction won’t change

            ○ If both half-reactions have the same reduction potentials (ex: both -) → voltage wont stop but cell potential will decrease

  • Electrons always flow from anode to cathode (“from A to C”)
  • Drawing half-cells:

            ○ Must indicate changes in (aq) and electrode (s); include spectator ion

            ○ The total charge must equal 0