SCH4U - Chemistry 12 (2024-25) - A

Summary

• The goal of a galvanic cell is to produce electricity through the movement of electrons. 
• A galvanic cell is made up of 2 half-cells, in one half-cell, a reduction reaction takes place while in the other half-cell an oxidation reaction takes place.  
• The two half-cells of a galvanic cell are connected externally by a metal wire through which electrons move, this external wire is often connected to a voltmeter or a component that requires electricity. 
• The two half-cells are connected internally by a salt bridge that functions to maintain electrical neutrality in each half cell. The salt bridge is made up of a tube that is filled with an electrolyte solution such as KNO₃ or KCl.
• Each half-cell is composed of a strip of metal (the electrode) immersed in a salt solution that contains ions made up of the same element as the metal strip. 
• The half-cell where reduction takes place is called the cathode. 
• The half-cell where oxidation takes place is called the anode.

• The electrical potential of a galvanic cell is a measure of its ability to produce an electric current.  Measured in units of volts (V).
• In a galvanic cell, the half-cell that has a greater tendency to acquire electrons will be the one where reduction occurs.
• The tendency of a half-cell to undergo the reduction reaction is called its reduction potential.
• The difference between the two reduction potentials is called the cell potential (E⁰_cell).
• E⁰_cell = E⁰_red - E⁰_oxid
• A redox reaction will occur spontaneously if E⁰_cell is positive.
• The hydrogen half-cell is used as the reference cell to measure all other standard reduction potentials.