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The jack of all chemicals
Hydrogen peroxide is one of the few compounds that possess a wide range of functions. Though apparently simple, it is a very effective and useful substance. But surprisingly, for years it was simply regarded as an agent to be used for bleaching hair.
Hydrogen peroxide can simply be defined as water — with just an extra atom of oxygen in its single molecule. This characteristic is also found in, albeit in traces, in rainwater and snow. This is because in the upper atmosphere rainwater comes in contact with the ozone layer and the ozone loses one of its atoms to water and subsequently hydrogen peroxide is formed, which becomes a part of rainwater or snowfall.
The H2O2 as it is chemically called is a colourless, syrupy liquid that serves as a strong oxidising agent when concentrated. It presents weak acidic characteristics if mixed with water. Its density is 1.48 times greater than that of water. Its melting point is -11°C (262 K), and boiling point is 141°C (414 K).
Hydrogen peroxide is soluble in alcohol and ether and it is miscible — a substance, especially a liquid, that can be mixed in all proportions — with cold water. Although pure hydrogen peroxide is fairly stable in low temperature ambience, but could be unstable in relatively higher temperatures. If exposed to a temperature of 80°C or above, the chemical undergoes decomposition and breaks down into water and a single oxygen molecule.
Furthermore, the presence of several catalysts, such as oxidisable organic material, certain metals and acids, causes it to decompose. Also, like other gases, oxygen is stable only when the molecules are in pairs. Otherwise a single molecule cannot continue to exist in its originality. This is why a single oxygen molecule serves as a strong oxidising and disinfecting agent.
Hydrogen peroxide plays a very important role in many physiologic processes and for this reason it is produced abundantly in the human body. Through the Peroxisomes (cell organelles containing enzymes to catalyse the production and breakdown of hydrogen peroxide) of the white blood cells, the discharge of hydrogen peroxide has been recognised as the primary response of the human body following an attack by pathogenic organisms.
The chemical also serves as a rocket fuel even though it is not widely recognised for this function. Actually, its use in rocketry, propulsion and power generation is very old.
German scientist and engineer Walterwerke will always be remembered for his contribution to research and development of hydrogen peroxide motors. Helmuth Walters Walterwerke developed a 1000kgf (kilogram force) hydrogen peroxide-propelled ATO (Auxiliary Take Off) rocket engine in 1936. His research work encompassed an extraordinary range of applications for hydrogen peroxide motors.
His first engine was a cold monopropellant rocket engine in which calcium permanganate solution was used to serve as a decomposition catalyst and hydrogen peroxide formed 80 per cent of the compound. Soon after this exercise, another rocket engine was built. This was a hot bipropellant (two-component rocket propellant, such as liquid hydrogen and liquid oxygen, which were fed one by one to the combustion chamber as fuel and oxidiser) rocket engine where once again 80 per cent of hydrogen peroxide was used to substantiate oxidation.
During World War II, perhaps the most recognized application of H2O2 was in the V2-rocket for the turbo-pump gas generator. The Germans, like in submarines and torpedoes, used hydrogen peroxide in quite a few other applications, but the most frequently used machine was a catapult that was operated on a 80 to 85 per cent H2O2 and calcium permanganate solution. A huge quantity of these catapults was produced and each catapult was used many times.
To energize the turbine for fuel pump of the V2/A4 rocket (long-range liquid-fuel rockets used by the Germans as a ballistic missile in World War II), the Germans used HTP (a high concentration solution of hydrogen peroxide, 85 to 98 per cent). Calcium permanganate was used, though in the shape of a very messy exhaust.
The Britons fancied the use of a-single-plated-nickel-gauze as a catalyst and they met with success. The high-test-peroxide was forced through the gauze and it was decomposed accordingly.
Hydrogen peroxide may also serve as a monopropellant (rocket propellants consisting of a single substance or mixture, which contains both fuel and oxidiser), but this lacks high effectiveness. In view of the fact that oxygen is produced in decomposition, fuels such as kerosene can be burnt in addition. The Rocket Propulsion Establishment at Westcott in Buckinghamshire built one of the first HTP motor.
Silver-plated wire mesh is used as a catalyst in the Gamma engines. The engines were designed and built to yield 20hrs run, while the catalyst had a life of just about 2 hours. This situation warranted certain capability in the design of the motors that can allow easy replacement of the catalyst.
The motor can be described as a simple combustion chamber with a flared vent and a restricted throat. The high-test-peroxide is forced all the way through the catalyst that results in the development of free oxygen and a superheated steam of 500O C.
Now the kerosene oil is forced into the chamber in such a manner that the spray is divided into finest squirts, for the reason to allow maximum contact with oxygen, which is then ignited due to the heat/temperature of steam. The throat temperature totters around 2300O C, while the temperature of the efflux holds at 1100O C.
The inability to supplement high efficiency is high-test-peroxide’s greatest drawback. The specific impulse (a performance measure for rocket propellants, which equals to units of thrust per unit weight of propellant consumed per unit time) of the rocket fuels provides the yardstick for the measurement of its effectiveness. The thrust produced per unit mass of fuel, burned per second, provides the basis to determine the effectiveness of the fuel.
In vacuum or absolute void condition, the specific impulse (also called specific thrust) of high-test-peroxide/kerosene can touch about 240 figure, liquid oxygen/kerosene approximately 280, and oxygen/hydrogen in excess of 400.
The motors that Walterwerke devised were meant to provide propulsion to aircraft, airborne missiles, remotely controlled craft and bombs. He also excelled in producing underwater weapons and rocketry and he developed mines, torpedoes and a range of high-speed boats and submarines.
The writer cocographer@yahoo.com is a senior instructor at a technical college
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