Molecules ozone

Quack M and Sutcliffe E 1983 Quantum interference in the IR-multiphoton excitation of small asymmetric-top molecules ozone Chem. Phys. Lett. 99 167-72... 

Since ozone is an unstable molecule, ozone has to be generated on-site. The various methods of ozone production differ in their working principles and ozone sources. The methods and their differences are summarized in Table 2-2. 

Oxidizer Chemical substance that causes oxygen to combine with another chemical substance examples include oxygen and hydrogen peroxide Ozone depletion Destruction of the stratospheric ozone layer that protects the Earth from harmful effects of ultraviolet radiation. Depletion of ozone layer is due to the breakdown of certain chlorine- and/or bromine-containing compounds (chlorofluorocarbons or halons), which break down when they reach the stratosphere and then catalytically destroy ozone molecules Ozone layer Protective layer in the atmosphere, about 15 miles above the ground. The ozone layer absorbs some of the sun s ultraviolet rays, thereby reducing the amount of potentially harmful radiation that reaches the Earth s surface PAHs Polycyclic aromatic hydrocarbons... 

In order to evidence variations in the molecular potential for isoelectronic molecules of very similar geometry, we consider now the triatomic non-linear molecules, ozone (XII) and nitrosyl fluoride (XIII). Potential maps in the molecular plane are reported for ozone in Fig. 16 and for FNO in Fig. 175>. Near the terminal oxygen atoms both molecules... 

Reaction (5.12) plays a significant role only in the thermosphere, where the concentration of atomic oxygen is large (i.e., 1012 cm-3 at 100 km). Reaction (5.13) is the only known mechanism in the atmosphere that leads to the formation of an ozone molecule. Ozone can recombine with atomic oxygen according to the reaction... 

The term standard state signifies the condition in which a substance is most stable at the temperature of the problem. (It has nothing to do with the standard temperature of the gas law problems, presented in Chapter 7.) Thus oxygen at 25°C is in its standard state as a gas in diatomic molecules. Ozone, O3, is not the standard state of oxygen, nor is a sample of O atoms or liquid O2. 

Figure 5.1 Elements that exist as gases at 25°C and 1 atm. The noble gases (the Group 8A elements) are monatomic species the other elements exist as diatomic molecules. Ozone (Os) Is also a gas.

Some elements can exist in different physical forms called allotropes alio means different, trap means form ). Different forms of the same element may have distinctly different chemical and physical properties. For example, carbon has several allotropes that include graphite and diamonds. Oxygen exists in the atmosphere mostly as diatomic molecules, O, but can also exist as the triatomic molecule ozone, O3. Ozone is significantly more reactive than O whereas O is essential to Ufe, O3 is harmful. Elements that are solids under standard conditions may have allotropes that differ primarily in their crystalline structures. 

Short-wavelength ultraviolet radiation (light with a wavelength less than 210 run) is the pump that drives the process. The single-oxygen atom species (O) that form are extremely reactive. They can collide either with an molecule and form ozone (as shown in the second chemical reaction in the cycle), or they can colUde with an O3 molecule and destroy ozone (as shown in the fourth chemical reaction in the cycle). Because the number of molecules is significantly greater than the number of O3 molecules, ozone formation is favored over ozone destruction. 

Student Annotation Recall that oxygen also exists as the triatomic molecule ozone (O3) Section 2.6]. Diatomic O2, however, is the more stable allotrope at room temperature. 

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