24.2.1—Terms
- Syllabus
- 9701–2028–2029
- Objective
- 24.2.1
- Level
- A2
Standard electrode potential compares a reduction half-cell under standard conditions
A standard electrode (reduction) potential E° is the potential of a half-cell measured relative to the standard hydrogen electrode under standard conditions, written as a reduction.
A standard cell potential is the difference between the cathode and anode reduction potentials: E°cell = E°cathode − E°anode. Do not multiply E° by stoichiometric coefficients.
If E°(Cu²⁺/Cu)=+0.34 V and E°(Zn²⁺/Zn)=−0.76 V, E°cell for Zn|Zn²⁺||Cu²⁺|Cu is +1.10 V.
E° values are not oxidation potentials unless the half-equation is reversed, and their numerical values are not scaled by balancing.
ConceptA-Level CAIE Chemistry A2