Gas-Phase Complexes in Hydrogen Chloride

Abstract

The null gap region of the fundamental band of HCl has been studied in the case where argon and xenon are used as perturbing gases. The experiments were performed using an absorption cell of 150 cm length. The absorption cell could be varied in temperature from room temperature to 195°K. The complex features previously observed in the spectrum at room temperature were greatly enhanced in intensity at the lowest temperature. The absorption spectrum of pure HCl gas was found to show strong evidence for dimer formation, which feature becomes strikingly evident at the lowest temperature employed. ``Arrhenius'' plots were made of the HCl–Ar, HCl–Xe, and the dimer data. The heats of formation were found to be 1.1, 1.6, and 2.14 kcal/mole, respectively, with a probable error of ±0.2 kcal/mole. The concentration of the dimer is estimated to be 1 part in 50 000 at 195°K at a gas density of 0.36 amagat.

Hydrogen forming reactions of thermal electrons in hydrogen halides: kinetics and thermodynamics

“…AE,31 for the H F dimer lies in the range -21 to -29 kJ mol-I (27,28). Discrete lines in the infrared spectrum of HC1 have also been attributed to a hydrogen bonded dimer (29,30) and from the temperature dependence of the integrated absorption intensities AEr3] was estimated to be 9.0 kJ mol-I.4 A slightly higher value of 11.3 kJ mol-I uas obtained in a CNDO calculation for a linear dimer (3 1). We found no published values of AE,,, for HBr, but one would expect it to become progressively smaller in the series HF, HCI, HBr due to the decrease in polarity.…”

Vibrational Relaxation of H2O by H2, HCl, and H2O at 295K

“…H20 and HCl are strong to moderate hydrogen bonding molecules with heats of dimerization of -6 kcal/mol and -2 kcal/mol, respectively. 13 , 25 The dominant influence of the attractive part of the intermolecular potential is seen in the large magnitude and negative temperature dependence of the self-relaxation probabilities of both molecules near room temperature and below. 2 ' 4 ' 24 The importance of rotational motion has also been demonstrated in deuteration studies of the self-relaxation of both molecules.…”

Theoretical study of the addition of hydrogen halides to olefins: A comparison between (HCl)2 and (HF)2 additions to ethylene

“…One is the stabilization energy of the HCl dimer amounting to 2.0 kcal/mol, which is in good agreement with the experimental value of 2.1 kcal/ mo1. 22 The other one is the extra stabilization of the product of the termolecular addition produced by the hydrogen bond between CH3CH2C1 and the new HC1 molecule formed in the reaction.…”