Galvanic Cell Notation

Rather than sketch the full apparatus every time a galvanic cell needs to be described, chemists use a compact, standardised line notation — the cell diagram — governed by a small set of IUPAC conventions. For the Daniel cell, this notation is written as

Read left to right, the notation follows these rules exactly:

• The anode is always written on the extreme left and the cathode on the extreme right.
• A single vertical bar (|) marks a phase boundary — a genuine physical interface between two different phases, such as a solid electrode against its aqueous ionic solution.
• A double vertical bar (||) represents the salt bridge, marking the boundary between the anodic (left) half-cell and the cathodic (right) half-cell.
• The emf of the cell is written after the full cell diagram, on the right.

This notation is a genuine shorthand map of the physical cell: walking through it left to right retraces the path electrons actually take, from the anode, through the (unwritten but implied) external circuit, to the cathode. …