Enthalpy and entropy of formation of the hydrated electron. [pulse radiolysis]
- Brookhaven National Lab., Upton, NY (United States)
Pulse radiolysis was used to study the equilibrium of the reaction e{sub aq}{sup {minus}} + NH{sub 4}{sup +} {r equilibrium} H{sm bullet} + NH{sub 3} in aqueous solution between 4 and 87 C. The rate of equilibrium was much larger than the subsequent radical decay. The equilibrium constant (corrected to zero ionic strength) is 2.2 at 25 C, {Delta}H{degree} is {minus}2.0 kcal/mol, and {Delta}S{degree} is {minus}5.1 cal/(deg mol). When combined with thermodynamic data for NH{sub 4}{sup +}{sub aq}, NH{sub 3,aq}, and H{sm bullet}{sub aq}, these values give {Delta}G{degree}{sub f}(e{sub aq}{sup {minus}}) = 66.2 kcal/mol, {Delta}H{degree}{sub f}(e{sub aq}{sup {minus}}) = 66.3 kcal/mol, and S{degree}(e{sub aq}{sup {minus}}) = 16 cal/(deg mol). The enthalpy is 1-3.7 kcal/mol than recently published values based on kinetic studies. The forward and reverse rate constants of the reaction with ammonium ion are 1.0 {times} 10{sup 6} and 0.67 {times} 10{sup 6} M{sup {minus}1} s{sup {minus}1} at 0.05 M ionic strength and 25 C. The activation energy of the forward reaction is 7.2 kcal/mol.
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 7017111
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:17; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
ACTIVATION ENERGY
AMMONIA
AMMONIUM COMPOUNDS
AQUEOUS SOLUTIONS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
DISPERSIONS
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
ENTHALPY
ENTROPY
EXPERIMENTAL DATA
FERMIONS
FORMATION HEAT
HYDRATION
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
LEPTONS
MIXTURES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NUMERICAL DATA
PHYSICAL PROPERTIES
RADIATION EFFECTS
RADIOLYSIS
REACTION HEAT
REACTION KINETICS
SOLUTIONS
SOLVATED ELECTRONS
SOLVATION
SPECTROSCOPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
THERMODYNAMIC PROPERTIES