24:6 Van Name and Edgar— Velocities of Certain Reactions 



Table V. 

 Zinc and Iodine at 25°. 



c 





At 



V 



K 



c 





M 



V 



K 



1. 100 g. 



KI 



per 



liter, r- 



=182 



2. 100 g. 



KI 



per 



liter, r- 



=240 





H 2 S0 4 = 



- N/100 







H 3 S0 4 = 



=N/100 





0-0339 

 0-0316 





5 



500 



480 



6-82 

 7-32 

 6-78 

 6-99 

 699 

 7-27 



0-0371 

 0-0339 





5 

 5 

 5 

 5 

 5 



500 



480 



8-59 

 8-53 



8-64 

 8-50 

 8-80 

 8-77 



0-0292 

 0-0270 

 0-0249 





5 



5 

 5 



460 

 440 

 420 



0-0309 

 0280 

 0-0253 





460 

 440 

 420 



0-0228 





400 



0-0227 





400 



0-0207 







380 



0-0202 







380 









Average 



7-03 









Average 



864 



3. 200 g. 



KI 



per 



liter, v- 



=240 



4. 200 g. 



K] 



per 



liter, r- 



= 240 





H 2 S0 4 = 



=N/100 





20 



g- 



Znl 2 



per liter. 





0-0390 





5 

 5 

 5 

 5 

 5 

 5 



500 



9-58 

 9-71 

 9-43 

 9-72 

 9-77 

 9-60 



9-64 





H 2 S0 4 = 



: N/100 





0-0353 





480 



0-0402 







500 





0-0318 

 0-0285 

 00254 

 0-0225 

 0-0198 





460 

 440 

 420 

 400 

 380 



Average 



0-0364 

 0-0329 

 0-0296 

 0-0264 

 0-0235 

 0-0207 









5 

 5 

 5 

 5 

 5 



480 

 460 

 44 

 420 

 400 

 380 



9-49 

 9-40 

 9-27 

 9-52 

 9-55 

 9 49 



















Average 



9-45 



like experiment 3, using the same zinc disk, repolished. 

 Unfortunately, through an oversight, the disk was not re- 

 measured for experiment 4, so that the correction for dimin- 

 ished thickness can only be roughly estimated. Allowing for 

 a correction of O04-O08, the constants for experiments 3 and 

 4 agree to within the possible error of experiment, so that they 

 can not be considered to confirm the observation of Schukarew. 

 Owing to lack of time this point was not further investigated. 



Bromine and Mercury. 



Bromine dissolved in potassium bromide solution of sufficient 

 strength reacts with mercury in much the same way as iodine. 

 Such a solution has, however, a considerable bromine vapor 

 pressure, and to measure the rate of reaction with a metal the 

 evaporation of bromine must either be prevented or a correc- 

 tion must be applied. We have followed the latter method. 



If the reaction with the metal is conducted and calculated 

 as in the case of iodine, disregarding the evaporation of bromine, 

 a fairly good constant is nevertheless obtained. The reason 

 for this is obvious. The vapor pressure of the bromine is 

 approximately proportional to its concentration in the solution, 



