354 G. A. Linhart — Rate of the Reduction of 



Although the equation, 



2HgCl 2 + H 3 P0 3 + H 2 = 2HgCl + H 3 P0 4 + 2HC1, (1) 



is in complete accord with the facts as far as the final result of 

 the reaction is concerned, it fails to account for its velocity; 

 for no one who has studied the velocity of the reaction has 

 been able to show that it is actually of the third order as this 

 equation would require. It is evident that if the reaction is of 

 the third order an increase in the concentration of phosphorous 

 acid to an amount about twenty times the theoretical quantity 

 required to reduce all of the HgCl 2 ought to produce fairly 

 concordant constants when the experimental results are substi- 

 tuted in a formula representing a reaction of the second order, 

 since the variation in the concentration of the phosphorous acid 

 is then very slight. Making use of this principle, the follow- 

 ing results were obtained : 



Table I. 



HgCl 2 = 0-005 mols per liter = A 

 H,P0 o = 0-050 " " « = B 



T = 25' 



t 

 in hrs. 



4-6 

 7-9 

 17-5 

 24*0 

 42-3 

 oo 



x = HgCl 



m grams 

 0*0052 

 0-0083 

 0*0140 

 0-0167 

 0-0212 

 0-0235 



in mols 

 0*001104 

 0-001760 

 0-002950 

 0-003546 

 0-004500 

 0-005000 



K 2 

 12-3 



13-7 

 16-4 

 20-3 

 42-5 



0-0541 

 0-0541 

 0-0511 

 0-0513 



0-0543 



t 

 in min. 



15- 



30- 

 45- 



75- 



00 



x - HgCl 



m grams 

 0-0103 

 0-0156 

 0-0194 

 0-0223 

 0-0235 



in mols 

 0-002187 

 0-003312 

 0-004114 

 0-004734 

 0-005000 



K 2 

 10-4 

 13-0 

 20-5 

 47-5 



60° 



0-0384 

 0-0361 

 0-0384 



0-0389 



K 2 was calculated from the equation K 2 = 



A 



K x from the equation K x = 



2-3 



t 



log 



im, r~ and 



A(A— x)t 



It is evident 



from the above results that the reaction is of the first order 

 with respect to the HgCl 2 . The " initial disturbance," there- 

 fore, observed by Montemartini and Edigi in the reduction of 

 mercuric chloride by phosphorous acid cannot be due to abnor- 



