The heat of formation of the ethyl radical

✍ Scribed by J-R. Cao; M. H. Back

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 278 KB
• Volume: 16
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550160803

✦ Synopsis

An examination of the results of measurements of the forward and reverse rate constants for the reaction

shows that agreement between the kinetics and the thermochemistry is achieved only through use of a value of AH,-(C,H5) = 28 kcal mol-'. This system therefore provides further support ?or the recent measurement of this quantity.

For an elementary reaction the forward and reverse rate constants are related through the equilibrium constant,

and independent measurements of each rate constant provide an exacting test of the validity of the measurements and of the thermochemistry of the system [l]. The systems involving dissociation of alkanes and combination of alkyl radicals were among the first to be subjected to this scrutiny [2,31. Measurements on the ethane-methyl radical system were satisfactorily resolved [4,51 but measurements of the corresponding rate constants for the dissociation of butane and the combination of ethyl radicals,

(3) TI, -CIH1,$2CzH, have not reached the same agreement [6,71. Following a recent measurement of the rate constant k -3 it was suggested [81 that the value for the heat of formation of the ethyl radical should be revised upwards