3 calories from amorphous carbon, and the heat of formation of liquid
water as 69 calories; this value for the heat of combustion of acetylene
makes its heat of formation to be 94.3 x 2 + 69 - 315.7 = -58.1 large
calories per gramme-molecule (26 grammes) from diamond carbon, or -52.1
from amorphous carbon. It will be noticed that the heat of combustion of
acetylene is greater than the combined heats of combustion of its
constituents; which proves that heat has been absorbed in the union of
the hydrogen and carbon in the molecule, or that acetylene is
endothermic, as elsewhere explained. These calculations, and others given
in Chapter IX., will perhaps be rendered more intelligible by the
following table of thermochemical phenomena:
_______________________________________________________________
| | | | |
| Reaction. | Diamond | Amorphous | |
| | Carbon. | Carbon. | |
|________________________________|_________|___________|________|
| | | | |
| (1) C (solid) + O . .
Pages:
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418