The voltage of a half-cell relative to the standard hydrogen electrode under standard conditions.
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A standard electrode potential is the voltage of a half-cell measured against the standard hydrogen electrode, with all solutes at 1 M, gases at 1 bar and the temperature at 25 C. Potentials are conventionally given for reduction half-reactions, and a more positive value indicates a stronger oxidizing agent. Because they are intensive properties, the values are not multiplied when a half-reaction equation is scaled. They allow the standard cell potential of any pair of half-cells to be calculated by subtraction. Tables of these values are a central resource in electrochemistry.
Key ideas: E standard is the potential of a half-cell under standard conditions (1 M, 1 bar, 25 C) tabulated as a reduction against the standard hydrogen electrode. Examples: Li+/Li -3.04 V, Zn2+/Zn -0.76 V, Cu2+/Cu +0.34 V, Ag+/Ag +0.80 V, F2/F- +2.87 V.
Common mistakes and connections: Potentials are intensive: do NOT multiply E by the coefficient when scaling a half-reaction. Reversing a half-reaction flips the sign. Students also forget the table lists reductions only. Use E cell = E cathode - E anode. Values change with concentration, as the Nernst equation shows.
Standard reduction potentials versus hydrogen: more positive means a stronger oxidizing agent, more negative a stronger reducing agent. The interactive lesson shows this as a live animation or chart.
The standard potential of Cu2+/Cu is +0.34 V, while that of Zn2+/Zn is -0.76 V.
The voltage of a half-cell relative to the standard hydrogen electrode under standard conditions.
Standard Electrode Potential is a intermediate topic in Acids, Bases & Electrochemistry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Acids, Bases & Electrochemistry first: Anode and Cathode, Salt Bridge, Cell Notation.
The next topics in Acids, Bases & Electrochemistry are Standard Hydrogen Electrode and Cell Potential.
Yes. The interactive lesson includes a self-check question on Standard Electrode Potential, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Standard Electrode Potential is topic 50 of 105 in Acids, Bases & Electrochemistry.