Absolute Determination of the Temperature Behavior of the NO<INF>2</INF> + NO<INF>3</INF> +(M) ↔ N<INF>2</INF>O<INF>5</INF> + (M) Equilibrium

The temperature dependence of the NO<INF>2</INF> + NO<INF>3</INF> + (M) ↔ N<INF>2</INF>O<INF>5</INF> + (M) equilibrium has been studied in the temperature range 279.6−294.2 K at a total pressure of 1000 mbar synthetic air in the 200 m³ EUPHORE simulation chamber facility in Valencia, Spain. Simultaneous determination of the concentration−time behaviors of NO<INF>3</INF>, NO<INF>2</INF>, and N<INF>2</INF>O<INF>5</INF> were obtained using the DOAS technique for detection of the NO<INF>3</INF> radical and FT-IR spectroscopy for detection of NO<INF>2</INF>, and N<INF>2</INF>O<INF>5</INF>. The experimental data are well described by ln([N<INF>2</INF>O<INF>5</INF>]/[NO<INF>2</INF>][NO<INF>3</INF>]) = −60.46 ± 0.26 + (10724 ± 75)/T where the errors given are random and expressed as 95% confidence limits. A critical comparison is made between the values of K<INF>eq</INF> determined in this work and those reported in the literature.