Final answer:
The standard emf is the standard reaction Gibbs energy expressed as a potential, reflecting the relationship between the standard cell potential and the Gibbs energy change for a reaction under standard conditions.
Step-by-step explanation:
The standard electromotive force (emf) of a cell is equivalent to the standard reaction Gibbs energy expressed in electrical units. This means that for a redox reaction occurring at standard conditions, which include a temperature of 298.15 K and concentrations of 1 M for solutes or 1 bar (or 1 atm) for gases, we have a specific measurement of potential known as the standard cell potential. The standard Gibbs energy (ΔG°) for a reaction can be determined by subtracting the Gibbs energies of formation of the reactants from those of the products, with values typically found in standard tables.
The Gibbs energy, also referred to as the Gibbs function or Gibbs Potential, is defined by the equation G = H - TS, where G is the Gibbs energy, H is the enthalpy, T is the temperature in Kelvin, and S is the entropy. The Gibbs energy change for a process with nonstandard conditions is related to the standard Gibbs energy change by a specific equation which takes into account deviations from standard pressures and concentrations.
The relationship between the standard cell potential (E°) and Gibbs energy (ΔG°) is formulated as ΔG° = -nFE°, where n is the number of moles of electrons transferred in the electrochemical reaction, F is Faraday's constant, and E° is the measured standard cell potential.