Stevens Institute of Technology Hoboken, New Jersey
I "
Examination of 62 general chemistry texts (high school and college) and 11 physical chemistry texts a t the book exhihit of the September 1959 ACS meeting showed that many are still presenting Faraday's laws of electrolysis virt,ually in the original form."ome are replacing them with the statement that 96.500 coulombs h o s t recent value 06.489.9 i- 2.0) passed through an electrolytic cell, will cause one gram equivalent weight of material to react or form a t an electrode. The advantages of this presentat,ion are recognized by many teachers. The following simple derivations of the single-equation statement, along the lines suggested hy Nopes and Sherrill,3 may have interest. Analysis of the two laws reveals that they concern three variables: quant,ity of electricity (charge, p), amount of mat,erial (mass, m), and gram equivalent weight (m,). In each laxv, one variable is held constant. The first law states that g is proportional to m when m, is constant, i.e., a particular substance in a particular Prcsent address: Inter American University, San Genn&n, Puerta Rico. 2 FARADAT, M., Phil. Trans.Roy. Soc. 124,77 (1834). 8 NOTES,A. A,, AND SHERRILI., M. Q., "A Coume of Study in Chemical Principles," The Macmillsn Co., New Yark, 2nd cd., 1938.
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Journal of Chemical Education
cell is being considered. The second lav states that if q is constant, m is proportional to me. A single proportionalit,y mhirh includes both statements is: 9%
Y"G
(1)
since, if m, is constant, q a m, and, if p is constant, m/m, = constant or m a me Rewriting (1) as an equation :
Calling this constaut F (for Faraday) and m/m, the number of equivalents, n :
is a mathematical statement of Faraday's law. This form of Faraday's law, with t,he definitions
can be used to solve readily all the general chemistry problems eom~nonlygiven on Faraday's laws.
