| Reference Label | Details |
|---|---|
| Dewey 1938 | P. H. Dewey and D. R. Harper, J. Res. Nat. Bur. Stand. 21, 457-474 (1938) Heats of Combustion of Anthracite Cokes and of Artificial and Natural Graphites |
| Rossini 1938 | F. D. Rossini and R. S. Jessup, J. Res. Nat. Bur. Stand. 21, 491-513 (1938) Heat and Free Energy of Formation of Carbon Dioxide, and of the Transition between Graphite and Diamond |
| note CO2 | Dewey 1938 reports the heats of combustion, -DeltaU, in int. kJ/mol, for solid carbon to form 1 mole of CO2 at 25.0° C and a pressure of 1 atm, without the production of external work, as follows: artificial graphite No. 0, 393.39 +- 0.17; artificial graphite No. 1, 393.25 +- 0.15, Ticonderoga natural graphite 393.32 +- 0.11, Buckingham natural graphite 393.35 +- 0.13; Baffin Island natural graphite, 393.37 +- 0.26. The used atomic weight for C is 12.010 (and also H 1.0078 and O 16.0000). The apparatus was calibrated by combusting benzoic acid. Hawtin 1966 shows all the corrections needed to bring this measurement to the current standards. The correction for external work to get -DeltaH298 is by addition of 11 int. J/mol as per Jessup 1938, but 12 int. J/mol as per Hawtin 1966. The correction to standard state is -33 int. J/mol as per Rossini 1938. The heat of combustion for benzoic acid used by Dewey 1938 to calibrate the bomb was subsequently shown to be in error by Prosen 1944 and this error necessitates a correction of +0.0336% to the heats of combustion (i.e. multiplication by a factor of 1.000336). Hawtin 1966 also convert this further from the molecular weight of CO2 used by Dewey 1938 of 44.010 to 44.011. (Dewey 1938 determine the mass of combusted graphite from the weight of CO2.) The current molecular weight of CO2 is 44.0095. The weighted average (average) of the heats determined by Dewey 1938 for their samples is 393.328 +- 0.062 (393.336) int. kJ/mol. With corrections of +12 and -33 int. J/mol and a correction for the calibration error of 1.000336 this produces 393.439 +- 0.062 (393.447) int. kJ/mol or 393.502 +- 0.062 (393.510) abs. J/mol or 94049.2 +- 14.7 (94051.2) cal/mol for 44.010 g CO2. or 94048.2 +- 14.7 (94050.1) cal/mol = 393.498 +- 0.062 (393.506) J/mol for the current molecular weight of CO2 of 44.0095. For purposes of comparison, this result is equivalent to 94052 +- 14.7 (94054.0) cal/mol for 44.011 g of CO2 (cf. with Hawtin 1966 mean of 94054 +- 24 cal/mol), Note that CODATA Key Vals quotes this result as 393.51 +- 0.10 kJ/mol and Cox 1970 quote it as 94050 +- 24 cal/mol = 393505 +- 100 J/mol. |
| note CO2c | Rossini 1938 re-evaluates the data of Jessup 1938 and Dewey 1938 and arrives at the weighted average enthalpy of combustion of graphite at 298.15 K to form 44.010 g of CO2 of -393355 +- 46 int. J/mol. Rossini 1940 restates the exact same result. This corresponds to -393418 +- 46 abs. J/mol, or for 44.0095 g of CO2 to 393.413 +- 46 abs. kJ/mol. This is slightly lower than our reinterpretation, see note CO2 and note CO2a, which produces a weighted average of 393.473 kJ/mol. Rossini also similarly analyses the combustion of diamond, arriving at -395254 - 115 int. J/mol. From these he derives the enthalpy for C |