as having begun the space age, used ethanol as the main constituent of b-stoff. under such nomenclature, the ethanol was mixed with 25% water to reduce the combustion chamber temperature. the v-2's design team helped develop u.s. rockets following world war ii, including the ethanol-fueled redstone rocket, which launched the first u.s. satellite. alcohols fell into general disuse as more energy-dense rocket fuels were developed, although ethanol is currently used in lightweight rocket-powered racing aircraft. fuel cells commercial fuel cells operate on reformed natural gas, hydrogen or methanol. ethanol is an attractive alternative due to its wide availability, low cost, high purity and low toxicity. there is a wide range of fuel cell concepts that have entered trials including direct-ethanol fuel cells, auto-thermal reforming systems and thermally integrated systems. the majority of work is being conducted at a research level although there are a number of organizations at the beginning of the commercialization of ethanol fuel cells. household heating and cooking ethanol fireplaces can be used for home heating or for decoration. ethanol can also be used as stove fuel for cooking. feedstock further information: § reactions ethanol is an important industrial ingredient. it has widespread use as a precursor for other organic compounds such as ethyl halides, ethyl esters, diethyl ether, acetic acid, and ethyl amines. solvent ethanol is considered a universal solvent, as its molecular structure allows for the dissolving of both polar, hydrophilic and nonpolar, hydrophobic compounds. as ethanol also has a low boiling point, it is easy to remove from a solution that has been used to dissolve other compounds, making it a popular extracting agent for botanical oils. cannabis oil extraction methods often use ethanol as an extraction solvent, and also as a post-processing solvent to remove oils, waxes, and chlorophyll from solution in a process known as winterization. ethanol is found in paints, tinctures, markers, and personal care products such as mouthwashes, perfumes and deodorants. polysaccharides precipitate from aqueous solution in the presence of alcohol, and ethanol precipitation is used for this reason in the purification of dna and rna. low-temperature liquid because of its low freezing point of −114 °c (−173 °f) and low toxicity, ethanol is sometimes used in laboratories (with dry ice or other coolants) as a cooling bath to keep vessels at temperatures below the freezing point of water. for the same reason, it is also used as the active fluid in alcohol thermometers. chemistry chemical formula ethanol is a 2-carbon alcohol. its molecular formula is ch3ch2oh. an alternative notation is ch3−ch2−oh, which indicates that the carbon of a methyl group (ch3−) is attached to the carbon of a methylene group (−ch2–), which is attached to the oxygen of a hydroxyl group (−oh). it is a constitutional isomer of dimethyl ether. ethanol is sometimes abbreviated as etoh, using the common organic chemistry notation of representing the ethyl group (c2h5−) with et. physical properties ethanol burning with its spectrum depicted ethanol is a volatile, colorless liquid that has a slight odor. it burns with a smokeless blue flame that is not always visible in normal light. the physical properties of ethanol stem primarily from the presence of its hydroxyl group and the shortness of its carbon chain. ethanol's hydroxyl group is able to participate in hydrogen bonding, rendering it more viscous and less volatile than less polar organic compounds of similar molecular weight, such as propane. ethanol's adiabatic flame temperature for combustion in air is 2082 °c or 3779 °f. ethanol is slightly more refractive than water, having a refractive index of 1.36242 (at λ=589.3 nm and 18.35 °c or 65.03 °f). the triple point for ethanol is 150 k at a pressure of 4.3 × 10−4 pa. solvent properties ethanol is a versatile solvent, miscible with water and with many organic solvents, including acetic acid, acetone, benzene, carbon tetrachloride, chloroform, diethyl ether, ethylene glycol, glycerol, nitromethane, pyridine, and toluene. its main use as a solvent is in making tincture of iodine, cough syrups, etc. it is also miscible with light aliphatic hydrocarbons, such as pentane and hexane, and with aliphatic chlorides such as trichloroethane and tetrachloroethylene. ethanol's miscibility with water contrasts with the immiscibility of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases. the miscibility of ethanol with alkanes is limited to alkanes up to undecane: mixtures with dodecane and higher alkanes show a miscibility gap below a certain temperature (about 13 °c for dodecane). the miscibility gap tends to get wider with higher alkanes, and the temperature for complete miscibility increases. ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture. mixing ethanol and water is exothermic, with up to 777 j/mol being released at 298 k. mixtures of ethanol and water form an azeotrope at about 89 mole-% ethanol and 11 mole-% water or a mixture of 95.6% ethanol by mass (or about 97% alcohol by volume) at normal pressure, which boils at 351 k (78 °c). this azeotropic composition is strongly temperature- and pressure-dependent and vanishes at temperatures below 303 k. hydrogen bonding in solid ethanol at −186 °c hydrogen bonding causes pure ethanol to be hygroscopic to the extent that it readily absorbs water from the air. the polar nature of the hydroxyl group causes ethanol to dissolve many ionic compounds, notably sodium and potassium hydroxides, magnesium chloride, calcium chloride, ammonium chloride, ammonium bromide, and sodium bromide. sodium and potassium chlorides are slightly soluble in ethanol. because the ethanol molecule also has a nonpolar end, it will also dissolve nonpolar substances, including most essential oils and numerous flavoring, coloring, and medicinal agents. the addition of even a few percent of ethanol to water sharply reduces the surface tension of water. this property partially explains the "tears of wine" phenomenon. when wine is swirled in a glass, ethanol evaporates quickly from the thin film of wine on the wall of the glass. as the wine's ethanol content decreases, its surface tension increases and the thin film "beads up" and runs down the glass in channels rather than as a smooth sheet. flammability an ethanol–water solution will catch fire if heated above a temperature called its flash point and an ignition source is then applied to it. for 20% alcohol by mass (about 25% by volume), this will occur at about 25 °c (77 °f). the flash point of pure ethanol is 13 °c (55 °f), but may be influenced very slightly by atmospheric composition such as pressure and humidity. ethanol mixtures can ignite below average room temperature. ethanol is considered a flammable liquid (class 3 hazardous material) in concentrations above 2.35% by mass (3.0% by volume; 6 proof). flash points of ethanol–water mixtures ethanol mass fraction, % temperature °c °f 184.5 184.1 264 147 2.3560 140 351.5 124.7 543 109 639.5 103.1 1031 88 2025 77 3024 75 4021.9 71.4 5020 68 6017.9 64.2 7016 61 8015.8 60.4 9014 57 10012.5 54.5 dishes using burning alcohol for culinary effects are called flambé. natural occurrence ethanol is a byproduct of the metabolic process of yeast. as such, ethanol will be present in any yeast habitat. ethanol can commonly be found in overripe fruit. ethanol produced by symbiotic yeast can be found in bertam palm blossoms. although some animal species, such as the pentailed treeshrew, exhibit ethanol-seeking behaviors, most show no interest or avoidance of food sources containing ethanol. ethanol is also produced during the germination of many plants as a result of natural anaerobiosis. ethanol has been detected in outer space, forming an icy coating around dust grains in interstellar clouds. minute quantity amounts (average 196 ppb) of endogenous ethanol and acetaldehyde were found in the exhaled breath of healthy volunteers. auto-brewery syndrome, also known as gut fermentation syndrome, is a rare medical condition in which intoxicating quantities of ethanol are produced through endogenous fermentation within the digestive system. production 94% denatured ethanol sold in a bottle for household use ethanol is produced both as a petrochemical, through the hydration of ethylene and, via biological processes, by fermenting sugars with yeast. which process is more economical depends on prevailing prices of petroleum and grain feed stocks. sources world production of ethanol in 2006 was 51 gigalitres (1.3×1010 us gal), with 69% of the world supply coming from brazil and the u.s. brazilian ethanol is produced from sugarcane, which has relatively high yields (830% more fuel than the fossil fuels used to produce it) compared to some other energy crops. sugarcane not only has a greater concentration of sucrose than corn (by about 30%), but is also much easier to extract. the bagasse generated by the process is not discarded, but burned by power plants to produce electricity. bagasse burning accounts for around 9% of the electricity produced in brazil. in the 1970s most industrial ethanol in the u.s. was made as a petrochemical, but in the 1980s the u.s. introduced subsidies for corn-based ethanol. according to the renewable fuels association, as of 30 october 2007, 131 grain ethanol bio-refineries in the u.s. have the capacity to produce 7×10^9 us gal (26,000,000 m3) of ethanol per year. an additional 72 construction projects underway (in the u.s.) can add 6.4 billion us gallons (24,000,000 m3) of new capacity in the next 18 months. in india ethanol is made from sugarcane. sweet sorghum is another potential source of ethanol, and is suitable for growing in dryland conditions. the international crops research institute for the semi-arid tropics is investigating the possibility of growing sorghum as a source of fuel, food, and animal feed in arid parts of asia and africa. sweet sorghum has one-third the water requirement of sugarcane over the same time period. it also requires about 22% less water than corn. the world's first sweet sorghum ethanol distillery began commercial production in 2007 in andhra pradesh, india. hydration ethanol can be produced from petrochemical feed stocks, primarily by the acid-catalyzed hydration of ethylene. it is often referred to as synthetic ethanol. c2h4 + h2o → ch3ch2oh the catalyst is most commonly phosphoric acid, adsorbed onto a porous support such as silica gel or diatomaceous earth. this catalyst was first used for large-scale ethanol production by the shell oil company in 1947. the reaction is carried out in the presence of high pressure steam at 300 °c (572 °f) where a 5:3 ethylene to steam ratio is maintained. this process was used on an industrial scale by union carbide corporation and others. it is no longer practiced in the us as fermentation ethanol produced from corn is more economical. in an older process, first practiced on the industrial scale in 1930 by union carbide but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentrated sulfuric acid to produce ethyl sulfate, which was hydrolyzed to yield ethanol and regenerate the sulfuric acid: c2h4 + h2so4 → ch3ch2so4h ch3ch2so4h + h2o → ch3ch2oh + h2so4 from carbon dioxide ethanol has been produced in the laboratory by converting carbon dioxide via biological and electrochemical reactions. co2 + h2o → ch3ch2oh + side products fermentation main article: ethanol fermentation