Post by Anders Hoveland on Feb 1, 2011 18:35:33 GMT -8
Ozone is potentially an ideal oxidizer since it is more energetic than liquid oxygen, but can burned with hydrogen without producing toxic hydrogen fluoride in the exhaust. There is, however, a significant explosion hazard.
Liquid oxygen enriched with ozone has been proposed as an energetic rocket oxidizer. It is claimed that the sensitivity of ozone to detonation is greatly reduced when care is taken to avoid even very small traces of hydrocarbon impurities. Even 4ppm impurities was enough to dangerously sensitize liquid ozone. Generally, previous observations of the danger of ozone toward explosion had not examined extremely pure samples free from trace impurities. The boiling point of oxygen is 90 K, while the boiling point for is ozone is 161 K. The liquid oxygen boils out from a mixture of ozone much faster, gradually increasing the concentration of ozone. When the concentration approaches 30 percent, below 93 K, the mixture separates into two distinct liquid layers, the first containing 30% ozone, and the second containing 75%. As more oxygen boils off, the volume of the 30% concentrated ozone layer decreases, while the volume of the 75% layer increases. This creates an unusual danger of explosion when trying to enrich liquid oxygen with ozone. However, addition of either 5% oxygen difluoride or of 9% liquid fluorine prevented layers from separating out in the liquid oxygen and ozone mixture, thus reducing danger of explosion.
Post by Anders Hoveland on Mar 17, 2012 23:55:33 GMT -8
There are several methods to prepare ozone by chemical means. All routes seem to suffer from relatively poor yields.
From Metal Peroxides 28 grams of ozone per cubic metre of oxygen evolved, by gently heating small quantities of powdered barium peroxide in eight times its volume of concentrated sulphuric acid. Hydrogen peroxide is likewise formed in small quantities under these conditions.
i. (2)H2SO4 + (2)BaO2 --> (2)BaSO4 + (2)H2O + O2 ii. H2SO4 + BaO2 --> BaSO4 + H2O2 iii. (3)H2SO4 + (3)BaO2 --> (3)BaSO4 + 4H2O + O3
The same investigator showed that similar results wore obtained with other peroxides, notably those of magnesium, zinc, sodium, and potassium.
From Permanganate Even better results can be obtained by the decomposition and gentle dehydration of permanganic acid or potassium dichromate, Mn2O7 --> 2MnO2 + O3.
De la Coux ("L'Ozone," p67) states that oxalic acid can be likewise employed in the proportion of 10 gms. of permanganate to 15 gms. of oxalic acid, and that 90 c.c. of oxygen containing 3 milligrams of ozone can be obtained from this mixture.
Satisfactory yields of ozone may also be obtained by cautious addition of barium peroxide to a solution of potassium permanganate in sulphuric acid, of density 1.85
From Persulfate By the thermal decomposition of the persulfates, small quantities of ozone can be obtained. 20 grams of dry freshly prepared ammonium persulfate are mixed with 15 gms. of nitric acid in a small flask. The air is subsequently displaced by carbon dioxide, and the mixture cautiously raised to 65° to 70° C. The reaction, which is strongly exothermic, proceeds somewhat vigorously when once started, and the resulting oxygen, after removal of the carbon dioxide, contains 3 to 5 per cent, of ozone and small quantities of nitrogen. Malaquin (" J. Pharm. Chem.," VII, 3, 329, 1911)
(one form of persulfate, peroxymonosulfate is available at many pool supply stores)
ozone, when liquified at -112 °C, is an indigo-violet liquid which is dangerously explosive. ozone gas is soluble in carbon tetrachloride.