Decomposition of nitrogen dioxide

This example shows that first-order kinetics are not restricted to reactions with just one starting material, such as the decomposition of nitrogen dioxide or the isomerization of s-2-butene. 

Many second-order reactions follow Class I rate expressions. Among these are the gas-phase thermal decomposition of hydrogen iodide (2HI - H2 + I2), dimerization of cyclopen-tadiene (2C5H6 -> C10H12), and the gas phase thermal decomposition of nitrogen dioxide (2N02 2NO + 02). 

The decomposition of nitrogen dioxide, 2N02 = 2N0 + 02, has a second order rate equation. Data at different temperatures are tabulated. Find the Arrhenius parameters. 

Ashmore and Burnett8 examined the thermal decomposition of nitrogen dioxide between 200 and 434°C. They found that log k 5 = 8.59 — 23.9/0. Using the values of 16.8 kcal/mole and 60 eu for the heat of formation and entropy of N03 (averaged from the results of Schott and Davidson371 and Ray and Ogg357), they found the equilibrium constant log J 5> 5 = 1.03 + 22.2/0, whence log k5 = 9.62 - 1.7/0. This leads to a value of 8.38 at room temperature. If thermodynamic values listed in JANAF tables are used, K5t 5 is larger at room temperature by a factor of 1.8 log k5 would be about 8.65. This paper is discussed further in Section IV-B-3. 

These conclusions were verified in a series of studies by Ashmore and co-workers8-12-281 on the kinetics of the reverse reaction, the thermal decomposition of nitrogen dioxide... 

An example is the thermal decomposition of nitrogen dioxide to yield NO and 02 ... 

Concentration-time data for the decomposition of nitrogen dioxide are given in Worked Example 12.8. What is the average rate of decomposition of NO2 during the following time periods ... 

Ozone forms in the upper stratosphere from molecular oxygen under the influence of UV solar radiation. In the lower stratosphere and troposphere, the source of ozone is the decomposition of nitrogen dioxide under the influence of UV and visible radiation. The formation of the vertical profile of ozone concentration is connected with its meridional and vertical transport. The general characteristic of this profile is the total amount of ozone measured by the thickness of its layer given in Dobson units (1 DU = 0.001 cm). 

Effect of Foreign Gas on the Photo-Decomposition of Nitrogen Dioxide at 0°... 

To introduce the concept of reaction rate, we will consider the decomposition of nitrogen dioxide, a gas that causes air pollution. Nitrogen dioxide decomposes to nitric oxide and oxygen as follows ... 

TABLE 15.2 Average Rate (in mol L-1 s 1) of Decomposition of Nitrogen Dioxide as a Function of Time... 

Chemical reactions are reversible. In our discussion of the decomposition of nitrogen dioxide, we have so far considered only the forward reaction ... 

Under conditions such that the reverse reaction can be neglected, the reaction rate depends only on the concentrations of the reactants. For the decomposition of nitrogen dioxide, we can write... 

So far we have only looked at irreversible reactions but as mentioned earlier all reactions are in principle reversible meaning that the reactions run in both directions. In the prior example with the decomposition of nitrogen dioxide the following reaction may also take place if there is excess O2 available ... 

Examples of such reactions are the decomposition of nitrogen dioxide to nitric oxide and oxygen in the gas phase. 

Second-order reactions are relatively conmum. We could mention the reaction between hydrogen and iodine to form hydrogen iodide or the decomposition of nitrogen dioxide according to... 

To illustrate the Euler and trapezoidal methods, we apply them to the following problem of chemical decomposition of nitrogen dioxide in a plug flow reactor. The chemical reaction rate is second order with respect to the nitrogen dioxide concentration that is. 

Shimokawabe, M., Ohi, A., Takezawa, N. (1992). Catalytic decomposition of nitrogen dioxide over various metal oxides. Applied Catalysis A General, 85, 129—133. 

The following data were obtained for the gas-phase decomposition of nitrogen dioxide at 300°C, N02fe) - NOfe) + i02(g) ... 

The decomposition of nitrogen dioxide is a second order reaction with rate constants as follows 522 M" s at 592 K,... 

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