354 Mixter — Determination of the Heat of Dissociation 



due to the 0-655 gram of ethylene. These data give 17,000 

 calories for the heat of dissociation of 28 grams of ethylene. 



Experiment 11. — The mixed gases used contained 0*707 

 gram of ethylene and 4*091 grams of acetylene. The gas 

 after explosion was freed from hydrocarbons. Jacket, 1*6°. 



Minutes. Temperature. 







1-88 



3 



1*88 



6 



1-S8 



9 



4*618 



12 



4*581 



15 



4*568 



18 



4*550 



21 



4*534 



24 



4*520 



Water and water equivalent of 

 calorimeter, 3252 grams. 



Temperature interval, 



4*581 — 1*88 +0*025 =2*726° 



These data give 18,900 c for the heat of dissociation of ethy- 

 lene. 



Experiment 12. — The bomb contained 1*952 gram of ethy- 

 lene and 5*045 grams of acetylene. The gas after explosion 

 was free from hydrocarbons. Jacket, 0° ; room, 0*35°. 



Minutes. Temperature. 



0*470 Water.. 3200 



3 0*470 Water eq. of calorimeter, 252 



6 0*470 ■ 



9 3*690 3452 grams. 



12 3*660 Temperature interval, 



14 3649 3*66 — 0-47 + 0*032 =3*222° 



17 3*628 



20 3*604 



23 3*587 



26 3*569 3452 . 3-222 = 11,122 calories. 



29 3*550 



From these data we deduce for the heat of dissociation of 

 28 grams of ethylene ll,200 c at constant volume and 10,600 c 

 at constant pressure. This result is probably the best of the 

 three because about three times as much ethylene was taken as 

 in the two preceding experiments. 



Experiment 13. — The gas used contained 93*7 per cent by 

 volume of ethylene. Hydrogen was assumed to constitute the 

 remainder, as it was found after removing ethylene. The 

 bomb contained 602 cc of the dry gas at 15-5° and 755*5 mm 

 pressure. The calculated amounts are 0*669 gram of ethylene 

 and 0*0032 gram of hydrogen. 3*2 grams of oxygen were 

 added. Jacket, 1*5°. 



