146 
IOWA ACADEMY OF SCIENCE 
velocity coefficients is considerable. This change is greater as the methyl 
alcohol increases. Again, consider a series in which the concentration of silver 
nitrate is the same, e.g. 0.0125N. The mean constants decrease with increase in 
the initial concentration of ethyl iodde, but the change is much less than in the 
former case. These facts, already observed by Durke and Donnan (loc. cit.) in 
the use of ethyl alcohol as solvent, are now applicable to these reactions carried 
out in methyl alcohol and in their binary mixtures. 
TABLE XI.— MEAN VELOCITY COEFFICIENTS OF THE REACTIONS BE- 
TWEEN SILVER NITRATE AND ETHYL IODIDE IN ALCOHOLS. 
Silver 
Ethyl 
75 per cent. 50 per cent. 
25 per cent. 
nitrate 
Iodide 
C2H50H 
25 per cent. -50 per cent. 
75 per cent. 
CH30H 
0.0125N 
0.05N 
0.00239 
__ 0.00294 
0.00410 
0.0125N 
0.025N 
0.002 VO 
0.00314 
0.00454 
0.0125N 
0.0125N 
0.00286 
0.00239 0.00380 
0.00380 
0.00557 
0.025N 
0.05N 
0.00274 
— 0.00417 
0.00589 
0.025N 
0.025N 
0.00345 
0.00396 0.00471 
0.00571 
0.00747 
0.025N 
0.0125N 
0.00380 
0.09465 0.00540 
0.00695 
0.00836 
0.05N 
0.05N 
0.00534 
0.00681 
0.0091S 
0.05N 
0.025N 
0.00638 
0.00921 
0.01342 
O.O'SN . 
0.0125N 
0.00589 
0.01080 , 
0.01625 
SUMMARY. 
The velocity coefficients of the reactions of thirty-three of the forty-five 
possible combinations of concentrations, using 0.05N, 0.025N, and 0.0125N 
solutions of silver nitrate and ethyl iodide in ethyl alcohol, methyl alcohol, and 
three of their primary binary mixtures, were obtained. 
The velocity coefficients of any particular reaction, calculated by the usual 
bimolecular equation, show in most cases a fairly constant value. However, 
they show a decrease as the reaction proceeds and this decrease is more marked 
in the methyl alcohol and in the mixtures than in the pure ethyl alcohol as 
solvent. 
Time-constant curves for any one concentration in the solvents used show a 
displacement toward the ethyl alcoholic solvent, thus indicating that this sol- 
vent has the greater infiuence on the reaction. 
This is also shown by plotting the mean velocity coefficients against solvents. 
A slight sagging of the curve shows that the velocity coefficients for the mixtures 
are a trifle smaller than would be expected from the law of averages. 
For the concentration considered, the coefficients are always greater in methyl 
alcohol than in ethyl alcohol as solvent. 
For any given initial concentration of ethyl iodide in the solvents used, the 
bimolecular velocity coefficients increase as the initial concentration of the 
silver nitrate increases. Fot a giyen initial concentration of silver nitrate, 
they decrease as the initial concentration of the ethyl iodide increases, but the 
change in the coefficients is very much less in the latter case. 
The difference in the effects of the two reacting constituents, which is ap- 
parently due to the presence of an excess or large amount of silver nitrate, 
increases as the proportion of methyl alcohol in the solvent increases. 
