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An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel’s octane rating. The mixture known as gasoline, when used in high compression internal combustion engines, has a tendency to ignite early (pre-ignition or detonation) causing a damaging "engine knocking" (also called "pinging" or "pinking") noise. Early research into this effect was led by A.H. Gibson and Harry Ricardo in England and Thomas Midgley, Jr. and Thomas Boyd in the United States. The discovery that lead additives modified this behavior led to the widespread adoption of the practice in the 1920s and therefore more powerful higher compression engines. The most popular additive was tetra-ethyl lead. However, with the discovery of the environmental and health damage caused by the lead, and the incompatibility of lead with catalytic converters found on virtually all US automobiles since 1975, this practice began to wane in the 1980s. Most countries are phasing out leaded fuel; different additives have replaced the lead compounds. The most popular additives include aromatic hydrocarbons, ethers and alcohol (usually ethanol or methanol). The typical antiknock agents in use are: 
Hematite: the main iron ore in Brazilian mines 
This stockpile of iron ore pellets will be used in steel production. A reducing agent (also called a reductant or reducer) is the element or compound in a reduction-oxidation (redox) reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized". This means that there must be an "oxidizer"; because if any chemical is an electron donor (reducer), another must be an electron recipient (oxidizer). Thus reducers are "oxidized" and oxidizers are "reduced". For example, consider the following reaction:
The reducing agent in this reaction is ferrocyanide (). It donates an electron, becoming oxidized to ferricyanide (), simultaneously the oxidizer chlorine is reduced to chloride. In organic chemistry, reduction more specifically refers to the addition of hydrogen to a molecule, though the aforementioned definition still applies. For example, benzene is reduced to cyclohexane in the presence of a platinum catalyst:
In organic chemistry, good reducing agents are reagents that deliver H2.
Chemical warfare (CW) involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from Nuclear warfare and Biological warfare, which together are the three tenets of NBC, the military acronym for Nuclear, Biological, and Chemical (warfare or weapons). Neither of these falls under the term conventional weapons which are primarily effective due to their destructive potential. Chemical warfare does not depend upon explosive force to achieve an objective. Rather it depends upon the unique properties of the chemical agent weaponized. A lethal agent is designed to injure or incapacitate the enemy, or deny unhindered use of a particular area of terrain. Defoliants are used to quickly kill vegetation and deny its use for cover and concealment. It can also be used against agriculture and livestock to promote hunger and starvation. With proper protective equipment, training, and decontamination measures, the primary effects of chemical weapons can be overcome. Many nations possess vast stockpiles of weaponized agents in preparation for wartime use. The threat and the perceived threat have become strategic tools in planning both measures, and counter–measures.
From Wikipedia, the free encyclopedia : Agents of fuels, ores, metals and chemical products |
