TABLE 415.— ELECTROCHEMICAL EQUIVALENTS 



403 



Every gram-atom involved in an electrolytic change requires the same number of 

 coulombs, or ampere-hours of electricity, per unit change of valency. This constant is 

 96487.7 coulomb/g-atom, or 26.801 ampere-hours per g-atom hour, corresponding to an 

 electrochemical equivalent of silver of 0.0011810 g sec _1 amp _1 . It is to be noted that 

 the change of valence of the element from its state before to that after the electrolytic 

 action should be considered. The valence of a free, uncombined element is to be considered 

 as 0. The same current will electrolyze "chemically equivalent" quantities per unit time. 

 The valence is then included in the "chemically equivalent" quantity. 



Change of Mg per 



Element valency coulomb 



Al 3 .09317 



CI 1 .36749 



" 3 .12250 



" 5 .07350 



" 7 .05250 



Cu 1 .6585 



" 2 .3293 



Au 1 2.044 



" 3 .6813 



H 1 .0104472 



Pb 1 2.1476 



" 2 1.07379 



" 4 .53690 



Hg 1 2.0792 



" 2 1.0396 



Ni 1 .60828 



" 2 .3041 



" 3 .20276 



O 2 .082914 



" 4 .041457 



Pt 2 1.01171 



" 4 .50585 



" 6 .33724 



K 1 .4052 



Ag 1 1.11810 



Na 1 .23835 



Sn 2 .61512 



" 4 .30756 



Zn 2 .33881 



Coulombs 

 per mg 



10.733 



2.7212 

 8.1633 

 13.605 

 19.048 

 1.5186 

 3.0367 



.4892 

 1.468 

 95.719 



.46564 



.93128 

 1.8625 



.48095 



.961908 



1.6440 



3.2884 



4.9319 



12.0607 



24.1214 



.98843 

 1.97687 

 2.9652 

 2.4679 



.894374 

 4.1955 

 1.6257 

 3.2514 

 2.9515 



G per 

 amp hour 



.3354 

 1.3230 



.4410 



.2646 



.1890 

 2.3706 

 1.1855 

 7.358 

 2.453 



.0376099 

 7.7314 

 3.8656 

 1.9328 

 7.4851 

 3.7426 

 2.1898 

 1.0948 



.7299 



.298490 



.14945 

 3.6422 

 1.82107 

 1.2140 

 1.4587 

 4.02516 



.85806 

 2.2144 

 1.1072 

 1.21972 



The electrochemical equivalent for silver is 0.00111810 g sec" 1 amp" 1 . For other elements 

 the electrochemical equivalent = (atomic weight divided by change of valency) and this 

 divided by 96487.7 coulomb/g-atom. 



SMITHSONIAN PHYSICAL TABLES 



