Unit 8: Electrochemistry Applications Lesson 1: The Electrochemical Cell

Two Types of Electrode An electrode is a conductor at which a half-reaction occurs. There are two types: the anode and the cathode. Remember: AN OX CARED – the ANode is where OXidation happens, and the CAthode is where REDuction happens.

Movement in the Cell Electrons move from the anode to the cathode (A to C, like the alphabet). Anions travel toward the anode, cations toward the cathode.

Example Let’s consider this cell in detail... SO42- Ag+ NO3- Cu2+

Example, continued The half-reactions in the cell are: Ag Ag+ + e- Cu Cu2+ + 2 e- Cu has a greater tendency to oxidize than Ag, so Cu will oxidize and become the anode. Ag will reduce and become the cathode. The electrons lost from Cu will travel through the wire to Ag (from anode to cathode!).

Brain Break! Double Shutter

Example, continued The two half-cells are separate so that electrons are forced to travel through the wire rather than move directly from one metal to the other. However, the salt bridge allows for ions to move from one half-cell to the other, in order to prevent charge imbalance.

Example, continued At the anode, as Cu2+ ions form, it creates an excess of positive charge. This attracts anions toward the anode. At the cathode, as Ag+ is depleted, it creates a lack of positive charge. This attracts cations toward the cathode.

Practice: Pg. 217 #34 and 35 25 min