Redox Reactions/galvanic cell

• Redox reactions involve the transfer of electrons from one chemical species to another. As such, they occur in two parts:

  • One of the reactants loses electrons in the process, oxidation
  • One of the reactants gain electrons in the process, reduction

  The species that undergo oxidation is called the reductant and the species that undergo reduction is called the oxidant
• Oxidation numbers are used to identify the reducing and oxidising agent in a redox reaction. This is done by comparing the conjugate charges of the product and reactant. An increase means the element has lost an electron and is undergoing oxidation while a decrease means it is being reduced.
• A galvanic cell is a electrochemical cell that converts chemical energy in electrical energy.

  • A galvanic cell consist of two half-cells. Each half-cell contains an electrode in a solution, which creates a conjugate redox pair.
  • Salt bridge contains ions which is used to balance the charges in the half-cell, acts as an internal circuit. Cheap and soluable.
• The potential difference is the tendency for one half-cell to push electrons into the external circuit. The potential difference of is measured with 1M solution in relation to hydrogen.
• Fuel cells are a type of electrochemical cell that requires a constant supply of fuels. Fuel cells are more expensive, more efficience but are more sustainable than combusion engines as water is produced. Fuel cells contain porous electrodes with electroyltes.