Dinitrogen tetroxide equilibrium pressure

In some cases it has been found possible to determine the rates of the opposing reactions, and to show experimentally that the ratio of the two rate constants is indeed equal to the equilibrium constant. This has not been done for the nitrogen dioxide-dinitrogen tetroxide equilibrium, however, because the individual chemical reactions take place so rapidly that expetimenters have not been able to determine their rates. It has, indeed, been found by experiment that if the pressure... 

The quantity K is called the equilibrium constant of the reaction of dissociation of dinitrogen tetroxide to nitrogen dioxide. The equilibrium constant is independent of the pressure of the system, or of the concentration of the reacting substances. It is, however, a function of the temperature. 

A mixture of nitrogen dioxide and dinitrogen tetroxide are allowed to come to equilibrium at 30 °C, and their partial pressures are found to be 1.69 atm N2O4 and 0.60 atm NO2. 

The study of physical equilibrium yields useful information, such as the equilibrium vapor pressure (see Section 11.8). However, chemists are particularly interested in chemical equilibrium processes, such as the reversible reaction involving nitrogen dioxide (NO2) and dinitrogen tetroxide (N2O4) (Figure 14.1). The progress of the reaction... 

Absorber performance is controlled by temperature and pressure. At reduced temperatures the gas-phase equilibrium moves toward the formation of dinitrogen tetroxide and an increased solubility in HNO3. Therefore, lower temperatures improve the absorption rate and increase the acid concentration. At higher pressures the NO oxidation reaction is quicker, and equilibrium moves toward nitrogen dioxide. In addition, with higher pressure more concentrated nitric acid is produced. 

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