Electromotive force cell voltage

E Electromotive force, cell voltage, electrode potential V... 

Since the electrolyte membrane only allows the conduction of ions, the electrons are forced through an exterior circuit, creating an electromotive force. The voltage generated by such a cell is given by the Nernst equation. For the hydrogen-oxygen reaction we can write ... 

Counter Electromotive Force A voltage of an electrochemical cell opposite to the applied external voltage. Also referred to as back EMF. 

Fig. 5. Energy requirements of the HaH-Hfiroult cell (23—25). E, decomposition of alumina Eg, depolarization by carbon E, anode overvoltage E, counter electromotive force E, bath voltage drop E, bath bubble voltage F/, anode voltage drop Eg, cathode voltage drop E, external voltage drop ...

Cell voltages (electromotive force of a complete cell)... 

While the voltage of the cell represents the potential difference between the two terminals of the battery, in reality it relates to the separation in energy between the two half-cells. We call this separation the emf where the initials derive from the archaic phrase electromotive force. An emf is defined as always being positive. 

The cell voltage is sometimes called the electromotive force, abbreviated emf. However, this term can be misleading. 

La photovoltaic cells, the same redox reaction, OX + e = KED, may be used for both the anode and the cathode. Figure 10-33 shows an eneigy diagram of an operating photovoltaic cell this cell consists of a metallic cathode and a photoexcited n-type semiconductor anode. The electromotive force (the open cell voltage), ph > approximately equals the difference between the flat band potential of... 

From the energy diagram shown in Fig. 10-33, the operating cell voltage, V,, is obtained, as expressed in Eqn. 10-60, by subtracting from the electromotive force AEph the potential barrier of the space charge layer, the cathodic overvoltage t h, and the iR drop in the electrolyte ... 

The portion AQ = AH - AG = TAS of AH is transformed into heat. Ideal theoretical efficiencies % determined by the types and amounts of reactants and by the operating temperature. Fuel cells have an efficiency advantage over combustion engines because the latter are subdued to the Carnot limitation. High thermodynamic efficiencies are possible for typical fuel cell reactions (e.g., e,h = 0.83 (at 25°C) for H2 + I/2O2 -> H20(i)). The electrical potential difference between anode and cathode, = -AG/W(f, which is also called the electromotive force or open-circuit voltage, drives electrons through the external... 

Now the applied voltage is the sum of the back electromotive force (emf) of the cell, Eback, and the iR drop through it, or... 

P The driving force of a cell / V I reaction, measured in volts and called cell voltage, cell potential, or electromotive force, is a function of the natural tendency of one substance to lose electrons and of a second substance to gain electrons. The greater these tendencies, the higher the cell voltage. 

The cell potential E (also called the cell voltage or electromotive force) is an electrical measure of the driving force of the cell reaction. Cell potentials depend on temperature, ion concentrations, and gas pressures. The standard cell potential E° is the cell potential when reactants and products are in their standard states. Cell potentials are related to free-energy changes by the equations AG = —nFE and AG° = —mFE°, where F = 96,500 C/mol e is the faraday, the charge on 1 mol of electrons. 

In general the electromotive force of a cell operating under reversible conditions is referred to as emf ( ), while that observed when conditions are irreversible is termed a voltage. In other words, emf, 8, is the maximum possible voltage that a galvanic cell can produce. 

In order to make the cell current zero we need to put an electrostatic voltage Ep in the cell circuit Fig. 9.6. This electrostatic voltage is called the electromotive force of the cell. The electrochemical cell is often described by a cell diagram such as shown in Eq. 9.16 ... 

This process leads to the development of a voltage difference between anode and cathode and when the external circuit is open , this potential difference is the electromotive force (the e.m.f.) of the cell. When there is an electrical load in the external circuit, for example a motor, then a current will flow and electrochemical energy is converted into mechanical energy. 

A single cell delivers a cell voltage between 0.5 and 0.9 V (instead of the theoretical electromotive force [emf] of 1.23 V under standard equilibrium conditions) depending on the working current... 

In other words, E is the electromotive force (EMF) of the reaction cell, where the voltage of the cell is unique for each reaction couple. Spontaneous processes have a negative free energy consequently, an electrochemical process will have a positive EMF. 

E Voltage (in volts), mostly electromotive force of a cell. 

The maximum of energy obtainable during the galvanic cell operation is expressed by the product of the quantity of electricity passed through the cell and the voltage across the electrodes, called the electromotive force of a cell (EMF). 

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