Browsing by Author "Alexander, Roger D."

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    Effect of temperature on the acid dissociation constants of 1,10-phenanthroline and some related bases in water
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (05), 1978) Alexander, Roger D.; Dudeney, A. William L.; Irving, Roger J.
    The acid dissociation constants (Ka) of the 1,10-phenanthrolium ion, 5-nitro-1,10-phenanthrolium ion, 2,9-dimethyl-1,10-phenanthrolium ion and 5,6-dimethyl-1,10-phenanthrolium ion in aqueous solution have been determined at various temperatures between 298 and 523 K. The temperature dependence of the pKa for each phenanthrolium ion is fitted by an equation of the form pKa=(A/T)–B+CT. The changes in enthalpy, entropy and free energy at each experimental temperature have been calculated from the temperature dependence of pKa.
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    Spectrophotometric Investigations of Aqueous Solutions at Elevated Temperatures
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (05), 1978) Alexander, Roger D.; Buisson, David H.; Dudeney, A. William L.; Irving, Roger J.
    The overall stability constants (β3) of the tris complexes of 1,10-phenanthroline, 5-nitro-1,10 phenanthroline and 2,2′-bipyridyl with iron (II) have been determined at various temperatures between 298 and 433 K by a new spectrophotometric method. The value of β3 for all three complexes decreases regularly with increasing temperature as expected. Plots of log10β3 against 1/T have been used to determine average values of the thermodynamic functions (enthalpy and entropy) of the formation reaction in aqueous solution over the experimental temperature range.