﻿MATHERS: PERCHLORIC ACID 



175 



This table shows a variety of results, but in general the yields 

 are fairly satisfactory. The best mixture seems to be: 10 cc. con- 

 centrated sulphuric acid, 1-5 cc. water, and 10 gms. of potassium 

 perchlorate. 



To ehminate the loss of perchloric acid due to action upon the 

 cork which connected the retort to the condenser, a glass tube 

 (to act as the inner tube of a Liebig condenser) was sealed to the 

 delivery arm of a 300 cc. distilling flask. A slight bend was made 

 in the delivery arm near the flask so that no material from the 

 flask could spatter into the condenser. Cold water was allowed to 

 flow over the receiving flask. Troublesome foaming was encountered 

 when quantities of potassium perchlorate greater than 20 gms. 

 were used. This foaming was increased by lowering the pressure 

 and by increasing the rapidity of cUstillation. Large crystals or 

 finely pulverized potassium perchlorate acted alike with reference 

 to foaming. The potassium perchlorate was attacked slowly by 

 the sulphuric acid. The crystals were stirred up and down in the 

 flask by the boiling and thus prevented bumping of the mixture. 

 With this improved apparatus appreciably better results were 

 obtained. This was partly due to better vacuum and to better 

 manipulation. The solidification of mono-hydratecl perchloric acid 

 in the condenser often plugged the condenser and spoiled the ex- 

 periment. The best plan to remove this plug was to seal a 

 stop-cock into the condenser tube between the water jacket and 

 the flask. The admission of a little water through this stop-cock 

 soon dissolved the crystallized acid. 



The following table gives the results with the all-glass apparatus. 

 Twenty gms. of potassium perchlorate was used in each experiment. 



Cc. 

 H.2SO4. 



Cc. 

 H,0. 



Pressure 

 in cm. Hg. 



Distillate 

 Contained 

 Grams of 



YieM, 

 Per 

 Cent. 



Remarks. 





















H,S04 



HCIO4 







20 



0 



0.6- 2 



0.9 



13.6 



94.2 



500 cc. flask, 34 full of foam . 



20 



0 



3.8 



0.87 



13.9 



96.5 



Time 18 minutes. 



20 



0 



2 - 3.2 



1.0 



14.0 



96. G 



500 cc. flask. Much foam.. 



20 



4 



4 3- 5.2 



3.7 



14.1 



97.5 



Large crystals KCIO4. 



20 



4 



12 -14 



1.2 



12.9 



89.2 



20 m.esh KCIO4. 



20 



' 



3.5- 6.7 



4.1 



13.7 



94.3 



20 mesh KCIO4. 



20 



4 



5 8- 7.5 



1.0 



13.7 



94.3 



20 mesh KCIO4. 



20 





2.2- 3.2 



4.5 



14.2 



97.9 



500cc.flask,3^ full of foam. 



