General Chemistry • Electrochemistry
Choose a cathode (kept as a reduction half-reaction) and an anode (its reduction half-reaction from the table will be reversed to oxidation). The calculator writes both half-reactions, the overall balanced reaction, and computes \( E^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} \). If \(E^\circ_{\text{cell}} < 0\), the cell is hypothetical (non-spontaneous as written).
Choose the cathode and anode half-reactions from a standard reduction potential table, then compute E°cell = E°cathode - E°anode. The anode value used in the formula is still its listed reduction potential even though the reaction is reversed to oxidation.
The cathode is where reduction occurs. In a spontaneous galvanic cell, the half-reaction with the more positive standard reduction potential is typically the cathode when the cell is written in the spontaneous direction.
A negative E°cell means the cell as written is not spontaneous under standard conditions. Swapping the cathode and anode would reverse the reaction direction and change the sign of E°cell.
No. Standard reduction potentials are intensive properties, so multiplying a half-reaction to match electrons does not change its E° value; only the stoichiometric coefficients change.
E°cell applies to standard conditions, typically 1 M for dissolved species and 1 atm (or 1 bar) for gases at a specified temperature. If concentrations or pressures are not standard, the actual cell potential differs from E°cell.