Electrochemical Cells

Electrochemical Cells

• An electrochemical cell is a device that generates electricity from a chemical reaction or uses electrical energy to drive a chemical reaction.
• Electrochemical cells can be classified into two types: voltaic (Galvanic) cells, which generate electricity from a spontaneous redox reaction, and electrolytic cells, which require a source of electricity to drive a chemical reaction.

Components of an Electrochemical Cell

• The main components of an electrochemical cell are the anode, the cathode, and the electrolyte.
• The anode and cathode are separated into two half-cells and connected by a metal wire.
• A salt bridge allows ions to flow between the two half-cells to complete the electrical circuit.
• The electrolyte solution provides ions or charged particles for the chemical reaction.

Anode and Cathode

• The anode and cathode are electrodes, typically made of metal conductors like Zinc and Iron.
• In a voltaic cell, the anode is negative and the cathode is positive, while in an electrolytic cell, the anode is positive and the cathode is negative.
• The anode is the site of oxidation, where electrons are lost, and the cathode is the site of reduction, where electrons are gained.

Half-Cell Reactions

• The reaction at the anode is an oxidation reaction, represented by the equation: Ox + ne- → Red
• The reaction at the cathode is a reduction reaction, represented by the equation: Ox + ne- → Red
• Using Zinc as the anode, the anode reaction is: Zn → Zn2+ + 2e-
• Using copper as the cathode, the cathode reaction is: Cu2+ + 2e- → Cu

Cell Notation

• Cell notation is a simplified way to represent the two half-reactions.
• The single lines represent a change between the solid and liquid or aqueous phase, and the double line represents the salt bridge that connects the half-cells.
• The anode is always written on the left of the double lines, and the cathode is always written on the right.

Electrochemical Potential (E cell)

• E cell is shorthand for the electrochemical potential of the cell, which is a measure of the energy the cell can produce.
• The electrochemical potential is a result of the difference in the number of charges of the anode and the cathode.
• The electrochemical potential can be calculated by finding the difference in the electrochemical potential of the cathode and anode.