The Amide Ion in Solution

Aqueous Solution. The standard free energy of hydration of NH2 is AG°= -389 kJ/mol at 298 K and 1 atm for a 1 M solution, calculated from the proton affinity of NH2 and thermodynamic data of NH3. The ionization potential of NH2,4.72 0.15 eV, was calculated from the value in the gas phase and the free energies of the anion and NH2 at 298 K [1]. 

Ammonia Solution. For the ammonolysis of gaseous NH2 at 240 K, a value of AS° = -239.6 J-K -mol was determined from experiments with NaNH2 and from estimated data [2]. A value of AH°= -289kJ/mol at 233 K for the solvolysis is given in [3]. Similar thermodynamic data for the amide formation in NH3 solution at 298 K were calculated from data measured on ions in aqueous solution [4]. 

AfH° = 41.0 1.2 kJ/mol at 240 K was calculated from the measured heat of amide neutralization and was confirmed by the heat of dissolution of KNH2 [2]. 

The mobility of NH2 in NH3 at 240 K, 133.0 cm - Q -Val is in the range of the mobilities of other anions and was calculated from mobility data and the equivalent ionic conductivity at infinite dilution [6]. 

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