Electrodes, Reactions, and Cell Capacity
This section focuses on the roles of electrodes, the reactions occurring in an electrochemical cell, and the concept of cell capacity.
The document defines the key components of an electrochemical cell:
Vocabulary:
When the electrodes of a cell are connected:
- An oxidation-reduction reaction occurs in the circuit
- Electrons move between the terminals of the cell
- Reactants are separated
Highlight: At the negative pole, electrons arrive (reduction occurs), while at the positive pole, electrons depart (oxidation occurs).
The role of the salt bridge is explained:
Definition: The salt bridge allows ions to move, ensuring current flow and maintaining electrical neutrality of the electrolytes.
The concept of cell depletion is introduced:
Vocabulary: A cell is a system out of equilibrium and functions as long as ΔrG < K (spontaneous reaction). A depleted cell reaches equilibrium when ΔrG = K.
The document then discusses the electrical capacity of a cell:
Definition: The capacity of a cell is the electric charge that circulates during its complete functioning period, measured in Coulombs.
Example: |Q| = N × e = ne × NA × e
For constant intensity: Q = I × Δt