How importants of Ozone to ouR EaRthZ!
December 10, 2008 
In ChemistRy!
Ozone is a powerful oxidizing agent, far better than dioxygen. It is also unstable at high concentrations, decaying to ordinary diatomic oxygen (in about half an hour in atmospheric conditions):
2 O3 → 3 O2
This reaction proceeds more rapidly with increasing temperature and decreasing pressure. Deflagration of ozone can be triggered by a spark, and can occur in ozone concentrations of 10 wt% or higher.
Metals
Ozone will oxidize metals (except gold, platinum, and iridium) to oxides of the metals in their highest oxidation state:
2 Cu1+(aq) + 2 H3O+(aq) + O3(g) → 2 Cu2+(aq) + 3 H2O(l) + O2(g)
Non-metals
Ozone also increases the oxidation number of oxides:
The above reaction the accompanied by chemiluminescence. The NO2 can be further oxidized:
NO2 + O3 → NO3 + O2
The NO3 formed can react with NO2 to form N2O5:
NO2 + NO3 → N2O5
Ozone reacts with carbon to form carbon dioxide, even at room temperature:
C + 2 O3 → CO2 + 2 O2
Ozone does not react with ammonium salts but it reacts with ammonia to form ammonium nitrate:
2 NH3 + 4 O3 → NH4NO3 + 4 O2 + H2O
Ozone reacts with sulfides to make sulfates:
Sulfuric acid can be produced from ozone, starting either from elemental sulfur or from sulfur dioxide:
S + H2O + O3 → H2SO4
3 SO2 + 3 H2O + O3 → 3 H2SO4
All three atoms of ozone may also react, as in the reaction with tin(II) chloride and hydrochloric acid and NaCl along with Ammonium Nitrate:
3 SnCl2 + 6 HCl + O3 → 3 SnCl4 + 3 H2O
In the gas phase, ozone reacts with hydrogen sulfide to form sulfur dioxide:
H2S + O3 → SO2 + H2O
In an aqueous solution, however, two competing simultaneous reactions occur, one to produce elemental sulfur, and one to produce sulfuric acid:
H2S + O3 → S + O2 + H2O
3 H2S + 4 O3 → 3 H2SO4
Iodine perchlorate can be made by treating iodine dissolved in cold anhydrous perchloric acid with ozone:
I2 + 6 HClO4 + O3 → 2 I(ClO4)3 + 3 H2O
Solid nitryl perchlorate can be made from NO2, ClO2, and O3 gases:
2 NO2 + 2 ClO2 + 2 O3 → 2 NO2ClO4 + O2
Combustion
Ozone can be used for combustion reactions and combusting gases; ozone provides higher temperatures than combusting in dioxygen (O2). The following is a reaction for the combustion of carbon subnitride which can also cause lower temperatures:
3 C4N2 + 4 O3 → 12 CO + 3 N2
Ozone can react at cryogenic temperatures. At 77 K (-196 °C), atomic hydrogen reacts with liquid ozone to form a hydrogen superoxide radical, which dimerizes:[10]
H + O3 → HO2 + O
2 HO2 → H2O4
Ozonides
Ozonides can be formed, which contain the ozonide anion, O3-. These compounds are explosive and must be stored at cryogenic temperatures. Ozonides for all the alkali metals are known. KO3, RbO3, and CsO3 can be prepared from their respective superoxides:
KO2 + O3 → KO3 + O2
Although KO3 can be formed as above, it can also be formed from potassium hydroxide and ozone:[11]
2 KOH + 5 O3 → 2 KO3 + 5 O2 + H2O
NaO3 and LiO3 must be prepared by action of CsO3 in liquid NH3 on an ion exchange resin containing Na+ or Li+ ions:[12]
CsO3 + Na+ → Cs+ + NaO3
Treatment with ozone of calcium dissolved in ammonia leads to ammonium ozonide and not calcium ozonide:[13]
3 Ca + 10 NH3 + 6 O3 → Ca•6NH3 + Ca(OH)2 + Ca(NO3)2 + 2 NH4O3 + 2 O2 + H2
Applications
Ozone can be used to remove manganese from water, forming a precipitate which can be filtered:
2 Mn2+ + 2 O3 + 4 H2O → 2 MnO(OH)2 (s) + 2 O2 + 4 H+
Ozone will also turn cyanides to the one thousand times less toxic cyanates:
CN- + O3 → CNO- + O2
Finally, ozone will also completely decompose urea:[14]
(NH2)2CO + O3 → N2 + CO2 + 2 H2O
Ozone in Earth’s atmosphere
The distribution of atmospheric ozone in partial pressure as a function of altitude.
Concentration of ozone as measured by the Nimbus-7 satellite.
Total ozone concentration in June 2000 as measured by EP-TOMS satellite instrument.
The standard way to express total ozone levels (the amount of ozone in a vertical column) in the atmosphere is by using Dobson units. Concentrations at a point are measured in parts per billion (ppb) or in μg/m³.
Ozone cracking
Ozone cracking in Natural rubber tubing
Ozone gas attacks any polymer possessing olefinic or double bonds within its chain structure, such materials including natural rubber, nitrile rubber, and Styrene-butadiene rubber. Products made using these polymers are especially susceptible to attack, which causes cracks to grow longer and deeper with time, the rate of crack growth depending on the load carried by the product and the concentration of ozone in the atmosphere. Such materials can be protected by adding antiozonants, such as waxes, which bond to the surface to create a protective film or blend with the material and provide long term protection. Ozone cracking used to be a serious problem in car tires for example, but the problem is now seen only in very old tires. On the other hand, many critical products like gaskets and O-rings may be attacked by ozone produced within compressed air systems. Fuel lines are often made from reinforced rubber tubing and may also be susceptible to attack, especially within engine compartments where low levels of ozone are produced from electrical equipment.
Laboratory production
In the laboratory, ozone can be produced by electrolysis using a 9 volt battery, a pencil graphite rod cathode, a platinum wire anode and a 3M sulfuric acid electrolyte.[36] The half cell reactions taking place are
3 H2O → O3 + 6 H+ + 6 e−; ΔEo = −1.53 V;
6 H+ + 6 e− → 3 H2; ΔEo = 0 V;
2 H2O → O2 + 4 H+ + 4 e−; ΔEo = −1.23 V;
so that in the net reaction three equivalents of water are converted into one equivalent of ozone and three equivalents of hydrogen. Oxygen formation is a competing reaction.
It can also be prepared by passing 10,000-20,000 volts DC through dry O2. This can be done with an apparatus consisting of two concentric glass tubes sealed together at the top, with in and out spigots at the top and bottom of the outer tube. The inner core should have a length of metal foil inserted into it connected to one side of the power source. The other side of the power source should be connected to another piece of foil wrapped around the outer tube. Dry O2 should be run through the tube in one spigot. As the O2 is run through one spigot into the apparatus and 10,000-20,000 volts DC are applied to the foil leads, electricity will discharge between the dry dioxygen in the middle and form O3 in O2 out the other spigot. The reaction can be summarized as follows:
3 O2 — electricity → 2 O3
bY: http://en.wikipedia.org/wiki/Ozone
