Page 5: Standard Hydrogen Electrode and Cell Notation
This page introduces the concept of the Standard Hydrogen Electrode (SHE) and explains cell notation, both crucial topics for understanding electrode potentials in A-Level Chemistry.
Definition: The Standard Hydrogen Electrode (SHE) is a primary reference electrode used to measure the standard electrode potentials of other half-cells.
Components of the Standard Hydrogen Electrode:
- Platinum electrode
- Hydrogen gas at 100 kPa (1 atm) pressure
- 1.0 M H⁺(aq) solution
- Temperature maintained at 298 K (25°C)
Highlight: The SHE is assigned a standard potential of 0.00 V, serving as the reference point for all other electrode potentials.
The page also explains cell notation, a shorthand method for representing electrochemical cells:
- Format: Reduced form | Oxidized form || Oxidized form | Reduced form
- Example: Pt(s) | H₂(g) | H⁺(aq) || Cu²⁺(aq) | Cu(s)
Vocabulary: Phase boundary - The interface between two different phases in an electrochemical cell, such as solid-liquid or gas-liquid interfaces.
Example: In a cell combining the SHE with a copper electrode:
Left half-cell: Pt(s) | H₂(g) | H⁺(aq)
Right half-cell: Cu²⁺(aq) | Cu(s)
Cell notation: Pt(s) | H₂(g) | H⁺(aq) || Cu²⁺(aq) | Cu(s)
Understanding the SHE and cell notation is essential for students working on setting up electrochemical cells with salt bridge lab reports and solving complex electrochemistry problems.