106 Van Name and Huff— Hydrolysis and Electrical 



complete. All were then treated with iodine at the same 

 time. 



In the experiments at 60° the procedure was slightly 

 altered to avoid the difficulties involved in taking the 

 reaction samples at this temperature with a pipette. 

 The reaction mixture was prepared at room temperature, 

 and like volumes were carefully measured out into a 

 series of glass tubes, which were then sealed and placed 

 in special weighted holders. When all were ready they 

 were inserted at the same time in the thermostat at 60°. 

 For the analyses heavy, wide-mouth, glass-stoppered 

 bottles were used instead of flasks, and the proper quan- 

 tities of sodium hydroxide and phosphate placed in each. 

 To make an analysis a tube was removed from the ther- 

 mostat and quickly shattered against the bottom of the 

 bottle, noting the time. After the fragments of the tube 

 had been broken up into small pieces with a heavy glass 

 rod, the analysis was carried out in the way already 

 described. 



The values of the velocity constant K, as given in the 

 following tables, were calculated from the -equation for 

 a monomolecular reaction, which here takes the form 



K = 2 - 3 (lo gl0 (T -TJ-log 10 (T t . -TJ); T„ T., and 



Tt representing cubic centimeters of thiosulphate re- 

 quired at the corresponding times. 



This equation assumes that the rate of hydrolysis is 

 proportional to the total concentration of the hypophos- 

 phoric acid molecules, ionized and non-ionized, thus 

 ignoring the possible differences in behavior between 

 the molecules and the different anions. In every experi- 

 ment with the exception of No. 6, where the conditions 

 were the least favorable for accuracy on account of the 

 excessively slow rate, the constancy of K is very satis- 

 factory, thus proving that the above equation is closely 

 obeyed. Whether this indicates a like rate of hydrolysis 

 for the molecules and the different anions of hypophos- 

 phoric acid, or shows, rather, that the reaction is almost 

 wholly confined to some particular kind of molecule or 

 ion whose concentration is closely proportional to the 

 total concentration of hypophosphoric acid, is a question 

 upon which these experiments throw no light. 



