- Cell EMF
- The electromotive force (EMF) is the maximum potential difference between two electrodes of a galvanic or voltaic cell. This quantity is related to the tendency for an element, a compound or an ion to acquire (i.e. gain) or release (lose) electrons.
- Chemical reactions in batteries or galvanic cells provide the driving force for electrons to struggle through loads. This is how chemical energy is transformed into electric energy. Electrolysis can be carried out in solutions or molten salts (liquid). Because the atoms and ions have to move physically, the medium has to be a fluid. The products, like the reactants in a galvanic cell, can be in a solid, liquid, or gas state.
- Half-Cell Reaction
- A half cell is one of the two electrodes in a galvanic cell or simple battery. For example, in the Zn−Cu battery, the two half cells make an oxidizing-reducing couple. Placing a piece of reactant in an electrolyte solution makes a half cell. Unless it is connected to another half cell via an electric conductor and salt bridge, no reaction will take place in a half cell.
- Nernst Equation
- Electrochemistry deals with cell potential as well as energy of chemical reactions. The energy of a chemical system drives the charges to move, and the driving force gives rise to the cell potential of a system called galvanic cell. The energy aspect is also related to the chemical equilibrium. All these relationships are tied together in the concept of the Nernst equation.
Contributors and Attributions
Chung (Peter) Chieh (Professor Emeritus, Chemistry @ University of Waterloo)