Gooch and Blake — Estimation of Bromic Acid. 285 



Art. XXXI. — The Estimation of Bromic Acid, hy the Direct 

 Action of Arseniotis Acid ; by F. A. Gooch and J. C. 

 Blake. 



[Contributions from the Kent Chemical Laboratory of Yale University — CXI.] 



In a former paper from this laboratory* it has been shown 

 that iodic acid may be reduced quantitatively by arsenious 

 acid. In the work of which the present paper is an account 

 the attempt has been made to apply arsenious acid similarly to 

 the quantitive estimation of bromic acid, according to the 

 equation 



3H3 AsO, + HBr03 = 3H3 AsO, + HBr. 



In the following series of experiments, made to discover the 

 limits within which regularity of action might be expected, 

 definite amounts of arsenious oxide dissolved in acid potassium 

 carbonate were mixed with measured portions of a solution of 

 potassium bromate, sulphuric acid was introduced in the 

 amounts indicated, and, after standing either at the ordinary 

 temperature, on the steam-bath or at the boiling temperature, 

 potassium acid carbonate was added and the arseniate remain- 

 ing was titrated with iodine to color, the indication being 

 confirmed by addition of starch. The conditions of acidity, 

 the excess of arsenious oxide, the dilution, the time of action, 

 and the temperature were varied within wide limits. The 

 potassium bromate for this particular series of experiments 

 was thrice recrystallized from water, dried at 110°, and made 

 up in solution containing 2'S grms. to the liter. Of this solution 

 25 or 50"''^ were measured out for each experiment. 









Table I. 













Volume not exceeding SOO'^''^^. 







KBr03 

 taken. 



AS0O3 

 taken. 



H2SO4 

 (1:1) 

 taken. 



Time oi 

 diges- 



AS2O3 

 unchanged. 



AsoOs 

 oxi- 

 dized. 



Error in 



terms of 



KBrOs. 



grm. 



grm. 



cm^. 



tion. 





grm. 



grm. 



grm. 







Heated at the boiling temperatur 



e. 





0-1400 



0-4950 



10 



30 min. 



0-2476 



0-2474 



0-0008- 



0-1400 



0-4950 



10 



30 





,0-2480 



0-2470 



0-0010 — 



0-1400 



0-6188 



10 



20 





0-3708 



0-2480 



0-0006— 



0-1400 



0-7425 



8 



25 





0-4941 



0-2484 



0-0003- 



0-1400 



0-7425 



8 



25 





0-4943 



0-2482 



0-0004 — 



0-1400 



0-6188 



7 



20 





0-3704 



0-2484 



0-0003 — 



0-1400 



0-6203 



7 



20 





0-3720 



0-2483 



0-0004- 



* Gooch and Pulman, this Journal, xii, p. 450 (1901). 



Am. Jour, Scl — Fourth Series, Vol. XIY, No. 82. — October, 1902. 

 20 



