Faraday Constant

(redirected from Faraday's constant)

Faraday constant

[′far·ə‚dā ‚kän·stənt]
(physics)

Faraday Constant

 

a fundamental physical constant equal to the product of Avogadro’s number NA and the charge of the electron e. The Faraday constant equals (9.648456 ± 0.000027) × 104 coulombs per mole. It is widely used in electrochemical calculations. The constant is named after M. Faraday, who discovered the fundamental laws of electrolysis.

References in periodicals archive ?
Where z is the number of moles of electrons exchanged in the reaction and F is Faraday's constant, 96 485 coulombs per mole of electrons.
where N0 represents the number of cells in series, E0 is the voltage denoting the reaction free energy, R and F are the universal gas constant and Faraday's constant, respectively stands for temperature while the If0 denotes the current of the SOFC stack [P.sub.H2] [P.sub.O], and [P.sub.H2O] are the partial pressure of hydrogen, oxygen and water, respectively and determined by using eq.
Table 1: SOFC Parameters Name Value Faraday's constant (F) 96484600 [C/kmol] Hydrosen valve constant 4.22 x [10.sup.-5] [kmol/(s atm)] [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] [K.sub.r] constant 2.2802 x [10.sup.-7] [kmol/(s A)] [N.sub.0]/4F No of cells in series 88 ([N.sub.0]) FC Internal Resistance (R) 0.00303 [[ohm]] FC absolute temperature (t) 343 [K] Universal gas constant (R) 8314.47 [J/(kmol K)] Oxygen valve constant 2.11 x [10.sup.-5] [kmol/(s atm)] ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]) Water valve constant 7.716 x [10.sup.-6] [kmol/(s atm)] ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII])
where A is the equivalent gram of the substance affected by the electrochemical dissolution process, U--the voltage applied on the electrodes, [DELTA]U- the voltage necessary for the electrodes polarization, k--the electroyte electric conductivity, F--the Faraday's constant, and [[rho].sub.m]--the substance mass density (for steel, nm= 7.8 g/[cm.sup.3]).
where F is Faraday's constant and [u.sub.i] is the limiting equivalent ionic mobility (mS.[cm.sup.2].mol/eq.C); the multiplier [10.sup.-6] is needed to maintain the dimensional consistence of the equation.
The value of Faraday's constant (96485 C/mol) is underestimated in the regression of [[summation of].sub.i][N.sub.i][u.sub.i] against EC.
When the activities were considered instead of the concentrations (second column of Table 6), the regression coefficients became closer to the theoretical value of Faraday's constant (96485 C/mol), especially for the saturation soil extracts from Griffin and Jurinak (1973).
The overestimation of the Faraday's constant was consistent with the use of the Debye-Huckel equation and Davies' equation to predict the activity coefficients of the ions by the speciation program SOILSOLN.
Coupled with that discovery was the well known quantitative determination of the charge-to-mass ratio, "e/m", (the basis of mass-spectrometry developed later) of the electron, and its absolute charge "e", by Townsend and, more reliably, by Millikan [7], and ultimately, with high accuracy, from the ratio, F/[N.sub.A], of Faraday's constant to Avogadro's number.
Called the Faraday's constant, its numerical value, 96488 C (coulomb) is the product of Avogadro's number ([N.sub.A] = 6.023 x [10.sup.23] ion/mol) and the fundamental electric charge ([e.sub.0]=1.602 x [10.sup.-19] coulomb); its more practical value is 26.8 Ah (amperehour).