Electrochemical cells

  • Redox reactions involve the transfer of elections
  • Electricity is simply the flow of electrons
  • Hence, having the reduction and oxidation reactions in two locations, with a wire to connect them and a salt bridge used to complete the circuit, a cell can be created
  • The flow of electrons in the wire creates electricity and can be used to power light bulbs etc.
  • Note whilst electron flow goes from the negative terminal to the positive terminal, conventional current flows the opposite way.

Also called: voltaic cell; Galvanic cell

  • A device that makes a normal chemical reaction occur in such a way that it generates electricity.
  • Electrodes: conductors of a cell which get connected to the external circuit
  • Reactions occurring at electrodes are called electrode process/reactions
  • The salt bridge allows ions to migrate and completes the circuit

 

  • One electrode (the anode) liberates electrons through oxidation which flows up the conductor
  • These electrons flow through the conductor to the other electrode (cathode)
  • The reaction at the cathode, reduction, consumes these electrons
  • Ions migrate through salt bridge to maintain electrical neutrality

 

An oil rig cat:

Oxidation occurs at the anode

Reduction occurs at the cathode

Example:

2 H+ + Zn + 2MnO2 –> Mn2O3 + Zn2+ + H2O

 

electrochemical cell

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