Understanding Electron Transfer and Redox Reactions

This section delves into the fundamental concepts of electron transfer and oxidation-reduction (redox) reactions, which form the basis of electrochemical cells.

Definition: An oxidation-reduction reaction involves the transfer of electrons between reactants.

The document introduces key terms and concepts:

Vocabulary:

• Reductant: An entity capable of donating electrons
• Oxidant: An entity capable of accepting electrons
• Oxidant/Reductant Couple: Represented by the equation Ox + ne⁻ = RED

The process of electron transfer is explained through half-equations:

Example:

• Oxidation: A half-equation modeling the loss of electrons
• Reduction: A half-equation modeling the gain of electrons

The concept of spontaneous electron transfer through an external circuit is introduced, leading to the discussion of electrochemical cells.

Highlight: Electrochemical cells facilitate spontaneous electron transfer through an external circuit.

The document then explains the constitution and functioning of electrochemical cells:

1. A cell consists of two half-cells
2. Each half-cell contains an electrolyte solution and an electrode
3. The half-cells are connected by a salt bridge

Definition: An electrolyte is a solution in which an electrode is immersed, containing the entities of an oxidation-reduction couple.

The flow of electric current in an electrochemical cell is described:

• In metal wires: Charges carried by electrons
• In solutions: Charges carried by ions
• Outside the generator: Current flows from the positive to the negative terminal

Highlight: Negative charge carriers move in the opposite direction of the electric current, while positive charge carriers move in the same direction.