Understandings
Applications
Figure 1. When a clean piece of copper metal is placed into a clear solution of silver nitrate (a), an oxidation-reduction reaction occurs that results in the exchange of Cu2+for Ag+ ions in solution. As the reaction proceeds (b), the solution turns blue (c) because of the copper ions present, and silver metal is deposited on the copper strip as the silver ions are removed from solution.
Figure 2. In this standard galvanic cell, the half-cells are separated; electrons can flow through an external wire and become available to do electrical work.
When the electrochemical cell is constructed in this fashion, a positive cell potential indicates a spontaneous reaction and that the electrons are flowing from the left to the right. There is a lot going on in Figure 2, so it is useful to summarize things for this system:
It is affected by ...
• temperature
• pressure of any gases
• solution concentrations