Cell notation

1. Definition

Cell notation is a shorthand representation of a Galvanic (Voltaic) cell, showing the electrodes, electrolytes, and salt bridge.

Start with the anode (where oxidation occurs) on the left.
Separate the electrode and electrolyte using a single vertical line $( | ).$
Represent the salt bridge using a double vertical line $( || ).$
End with the cathode (where reduction occurs) on the right.
Inert electrodes (e.g., Platinum $(Pt)$ or Carbon $(C)$ ) are used when a metal electrode is not involved in the reaction.

infoNote

Cell Reaction:

$Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s)$

Cell Notation:

$Zn(s) | Zn^{2+}(aq) || Cu^{2+}(aq) | Cu(s)$

If no solid metal is involved, a $Pt$ (Platinum) or $C$ (Graphite) electrode is used.
Example: $Iron(III)$ $I ro n (III)$ to $Iron(II)$ $I ro n (II)$ Reduction
- Reaction: $Fe^{3+} + e^- \rightarrow Fe^{2+}$
- Cell Notation: $Pt | Fe^{3+}(aq), Fe^{2+}(aq) || Cl⁻(aq) | Cl₂(g) | Pt$

Oxidation (anode) is written on the left, and reduction (cathode) is on the right.
A single vertical line $( | )$ separates an electrode from its electrolyte.
A double vertical line $( || )$ represents the salt bridge.
Platinum $(Pt)$ is used as an inert electrode when no solid metal is present.