CHEMISTRY: J. H. ELLIS 
85 
volts and the values of the free-energy-decrease in joules calculated from 
them by the equation Fi - F2 = 96500 E X 4.182 are given in Table 1. 
These electromotive forces are probably not in error in any case by as 
much as 0.1 millivolt. The free-energy-decrease is that attending the 
cell-reaction J H2 (1 atm.) + JHgsClz (solid) = Hg (Hquid) + H+Cl" (at 
concentration c). The table also contains the values of the increase 
(H2 — Hi) in the heat-content of the cell when this reaction takes 
place at 25°, calculated by the fundamental thermodynamic equation: 
II2 — Hi 
T2 
TABLE 1 
Energy-Effects Relating to the Reaction 
I H2 (1 Atm.) + i Hg2Cl2 = Hg+HCl (at Various Concentrations). 
MOLS HCl 
PER 1000 G. WATER 
ELECTROMOTIVE FORCE AT 
FREE-ENERGY DECREASE AT 
HEAT 
DECREASE 
AT 25 
18" 
25° 
35° 
18" 
25° 
35° 
4.484 
0.15759 
0.15506 
0.15124 
15208 
14964 
14595 
25590 
1.9278 
0.23769 
0.23589 
0.23304 
22937 
22764 
22489 
30480 
1.0381 
0.27919 
0.27802 
0.27595 
26942 
26829 
26629 
32130 
0.7714 
0.29654 
0.29571 
0.29411 
28616 
28536 
28381 
32450 
0.5095 
0.31912 
0.31865 
0.31765 
30795 
30750 
30654 
33070 
0.3376 
0.33845 
0.33836 
0.33794 
32661 
32652 
32611 
33380 
0.1004 
0.39764 
0.39884 
0.40013 
38373 
38489 
38612 
34060 
0.0333 
0.45020 
0.45258 
0.45557 
43444 
43674 
43963 
34370 
In Table 2 are given the corresponding values of the free energy of 
transfer and heat of transfer of 1 HCl from solutions of various concen- 
trations to a solution of the concentration 0.1000 mols HCl per 1000 g. 
water. These are obtained from the values of Table 1 by direct sub- 
traction (after reducing the values at the concentration 0.1004 so as 
to correspond to the round concentration 0.1000). In the table are 
included also values of the free energy of transfer at 18° for concentrations 
below 0.0333 molal, these having been calculated from Jahn^s^ measure- 
ments of the electromotive force of concentration-cells of the type 
Ag-l-AgCl, HCl (ci), HCKcs), AgCl-fAg. In the next to last column 
of the table are given the corresponding values of the activity-coefhcients 
at 18°, calculated by the equation given above on the assumption that 
at the smallest concentration (0.00167 molal) the activity-coefiicient 
is equal to the ionization- coefficient (0.988) derived from the ratio of 
the equivalent conductance at that concentration to that extrapolated 
for zero concentration. The last column of the table gives the values 
