Kinetics and thermochemistry of the reversible gas phase reaction HONO+NH3⇌H3H-HONO studied by infrared diode laser spectroscopy

✍ Scribed by Palle Pagsberg; Emil Ratajczak; Alfred Sillesen; Zdzislaw Latajka

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 643 KB
• Volume: 227
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(94)00787-x

✦ Synopsis

The kinetics of the reversible reaction HONO+NH,eH,N-HONO

( 1) was studied by monitoring tram-HONO relaxation kinetics. The rate of approach towards equilibrium was studied as a function of the ammonia concentration to obtain values of the rate constants for the forward and reverse reactions as well as the equilibrium constant. At 298 K we have determined the following values for the forward rate constant and the equilibrium constant, klr= (2.2+0.2)x 10' M-r s-* and Kc= ( 1.5 + 0.2) x 1 O5 M-'. The equilibrium constant was determined at temperatures in the range of 287-3 19 K, and from the observed temperature dependence expressed in terms of the van 't Hoff equation we have derived the following values of AH0 rg8 = -11.8 + 0.8 kcal/mol and AS$&s = -26.7 f 1 .O cal/mol K. Theoretical investigations of the structure and thermochemistry of the H,N-HONG hydrogen bonded complex were carried out on the electron correlation level and 6-3 1 1 + G( 2df, 2pd) basis set. The calculated binding energy is -10.1 kcal/mol while AIY q9s = -8.1 kcal/mol and A.Sq9s = -26.70 cal/mol K.