OZONE

Ozone is a molecule that consists of three oxygen atoms (3x0=O3). With its oxidation power, it is an efficient disinfectant, characterized by its rapidity and the low concentrations required.

It has the ability to destroy not only bacteria but also viruses including Noro-virus, spores, fungus and many other contaminants by oxidation.

Ozone is non-toxic in a concentration not exceeding a certain level. It will revert back to its original form, namely oxygen (O2) within a short period of time.

Therefore, ozone will not leave any residues of itself. Ozone is widely used in the food industries. It is also admitted as food additive.

Ozone in the upper atmosphere filters potentially damaging ultraviolet light from reaching the Earth's surface. It is present in low concentrations throughout the Earth's atmosphere . It has many industrial and consumer applications. Ozone, the first allotrope of a chemical element to be recognized by science, was proposed as a distinct chemical compound by Christian Friedrich Schönbein in 1840, who named it after the Greek word for smell (ozein), from the peculiar odor in lightning storms. The formula for ozone, O 3 , was not determined until 1865 by Jacques-Louis Soret and confirmed by Schönbein in 1867.

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 O 3 ? 3 O 2 .

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. Ozone will oxidize metals (except gold , platinum , and iridium ) to oxides of the metals in their highest oxidation state :

2 Cu 2+ (aq) + 2 H 3 O + (aq) + O 3(g) ? 2 Cu 3+ (aq) + 3 H 2 O (l) + O 2(g)

Ozone also increases the oxidation number of oxides:

NO + O 3 ? NO 2 + O 2

The above reaction is accompanied by chemiluminescence . The NO 2 can be further oxidized:

NO 2 + O 3 ? NO 3 + O 2

The NO 3 formed can react with NO 2 to form N 2 O 5 :

NO 2 + NO 3 ? N 2 O 5

Ozone reacts with carbon to form carbon dioxide , even at room temperature:

C + 2 O 3 ? CO 2 + 2 O 2

Ozone does not react with ammonium salts but it reacts with ammonia to form ammonium nitrate :

2 NH 3 + 4 O 3 ? NH 4 NO 3 + 4 O 2 + H 2 O

Ozone reacts with sulfides to make sulfates :

PbS + 4 O 3 ? PbSO 4 + 4 O 2

Sulfuric acid can be produced from ozone, starting either from elemental sulfur or from sulfur dioxide :

S + H 2 O + O 3 ? H 2 SO 4

3 SO 2 + 3 H 2 O + O 3 ? 3 H 2 SO 4

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 SnCl 2 + 6 HCl + O 3 ? 3 SnCl 4 + 3 H 2 O

In the gas phase , ozone reacts with hydrogen sulfide to form sulfur dioxide:

H 2 S + O 3 ? SO 2 + H 2 O

In an aqueous solution, however, two competing simultaneous reactions occur, one to produce elemental sulfur, and one to produce sulfuric acid:

H 2 S + O 3 ? S + O 2 + H 2 O

3 H 2 S + 4 O 3 ? 3 H 2 SO 4

Iodine perchlorate can be made by treating iodine dissolved in cold anhydrous perchloric acid with ozone:

I 2 + 6 HClO 4 + O 3 ? 2 I(ClO 4 ) 3 + 3 H 2 O

Solid nitryl perchlorate can be made from NO 2 , ClO 2 , and O 3 gases:

2 NO 2 + 2 ClO 2 + 2 O 3 ? 2 NO 2 ClO 4 + O 2

Ozone can be used for combustion reactions and combusting gases in ozone provides higher temperatures than combusting in dioxygen (O 2 ). Following is a reaction for the combustion of carbon subnitride which can also cause lower temperatures:

3 C 4 N 2 + 4 O 3 ? 12 CO + 3 N 2

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:

H + O 3 ? HO 2 + O

2 HO 2 ? H 2 O 4

Ozonides can be formed, which contain the ozonide anion, O 3 - . These compounds are explosive and must be stored at cryogenic temperatures. Ozonides for all the alkali metals are known. KO 3 , RbO 3 , and CsO 3 can be prepared from their respective superoxides:

KO 2 + O 3 ? KO 3 + O 2

Although KO 3 can be formed as above, it can also be formed from potassium hydroxide and ozone:

2 KOH + 5 O 3 ? 2 KO 3 + 5 O 2 + H 2 O

NaO 3 and LiO 3 must be prepared by action of CsO 3 in liquid NH 3 on an ion exchange resin containing Na + or Li + ions:

CsO 3 + Na + ? Cs + + NaO 3

Treatment with ozone of calcium dissolved in ammonia leads to ammonium ozonide and not calcium ozonide:

3 Ca + 10 NH 3 + 6 O 3 ? Ca•6NH 3 + Ca(OH) 2 + Ca(NO 3 ) 2 + 2 NH 4 O 3 + 2 O 2 + H 2

Ozone can be used to remove manganese from the water , forming a precipitate which can be filtered:

2 Mn 2+ + 2 O 3 + 4 H 2 O ? 2 MnO(OH) 2 (s) + 2 O 2 + 4 H +

Ozone will also turn cyanides to the one thousand times less toxic cyanates :

CN - + O 3 ? CNO - + O 2

Finally, ozone will also completely decompose urea :

(NH 2 ) 2 CO + O 3 ? N 2 + CO 2 + 2 H 2 O

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