Faraday constant, 1.5

Electrostatic Interaction. Similarly charged particles repel one another. The charges on a particle surface may be due to hydrolysis of surface groups or adsorption of ions from solution. The surface charge density can be converted to an effective surface potential, /, when the potential is <30 mV, using the foUowing equation, where -Np represents the Faraday constant and Ai the gas law constant. 

Coulometry. If it can be assumed that kinetic nuances in the solution are unimportant and that destmction of the sample is not a problem, then the simplest action may be to apply a potential to a working electrode having a surface area of several cm and wait until the current decays to zero. The potential should be sufficiently removed from the EP of the analyte, ie, about 200 mV, that the electrolysis of an interferent is avoided. The integral under the current vs time curve is a charge equal to nFCl, where n is the number of electrons needed to electrolyze the molecule, C is the concentration of the analyte, 1 is the volume of the solution, and F is the Faraday constant. 

The ionic mobility is the average velocity imparted to the species under the action of a unit force (per mole), i is the stream velocity, cm/s. In the present case, the electrical force is given by the product of the electric field V in V/cm and the charge per mole, where S" is the Faraday constant in C/g equivalent and Z is the valence of the ith species. Multiplication of this force by the mobihty and the concentration C [(g mol)/cm ] yields the contribution of migration to the flux of the ith species. 

Where R is the gas constant, T the temperature (K), Fthe Faraday constant and H2 is the relative partial pressure (strictly, the fugacity) of hydrogen in solution, which for continued evolution becomes the total external pressure against which hydrogen bubbles must prevail to escape (usually 1 atm). The activity of water a jo is not usually taken into account in elementary treatments, since it is assumed that <7h2 0 = U nd for dilute solutions this causes little error. In some concentrated plating baths Oh2 0 I O nd neither is it in baths which use mixtures of water and miscible organic liquids (e.g. dimethyl formamide). However, by far the most important term is the hydrogen ion activity this may be separated so that equation 12.1 becomes... 

Faraday Constant (F) the quantity of electric charge involved in the passage of one Avagadro number (or one mole) of electrons. The value of F (universal) is 96 485 C mol . ... 

Faraday s Law the quantity of charge (Q) passed in an electrochemical reaction is directly proportional to the number of moles (n) of substance reacted. Thus Q = zFn, where z is the number of electrons involved in one molecule of the reaction and F is the Faraday constant. 

An electrolysis experiment is performed to determine the value of the Faraday constant (number of coulombs per mole of electrons). In this experiment, 28.8 g of gold is plated out from a AuCN solution by running an electrolytic cell for two hours with a current of 2.00 A. What is the experimental value obtained for the Faraday constant ... 

Faraday constant The constant that gives the number of coulombs equivalent to one mole of electrons 96480 C/mol e, 491,496... 

Coulometric analysis is an application of Faraday s First Law of Electrolysis which may be expressed in the form that the extent of chemical reaction at an electrode is directly proportional to the quantity of electricity passing through the electrode. For each mole of chemical change at an electrode (96487 x n) coulombs are required i.e. the Faraday constant multiplied by the number of electrons involved in the electrode reaction. The weight of substance produced or consumed in an electrolysis involving Q coulombs is therefore given by the expression... 

The constant 607 is a combination of natural constants, including the Faraday constant it is slightly temperature-dependent and the value 607 is for 25 °C. The IlkoviC equation is important because it accounts quantitatively for the many factors which influence the diffusion current in particular, the linear dependence of the diffusion current upon n and C. Thus, with all the other factors remaining constant, the diffusion current is directly proportional to the concentration of the electro-active material — this is of great importance in quantitative polarographic analysis. 

F-test 140, (T) 841 Faraday constant 60, 504 Faraday s laws 503, 504 Fast sulphon black F 319 Fats D. of saponification value, (ti) 308 Ferric alum indicator see Ammonium iron(III) sulphate... 

With the definition of the Faraday constant (Eq. 13) the amount of charge for the cell reaction for one formula conversion is given by Eq. (18) ... 

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