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Distillation

Distillation

] Distillation is physical process for separating liquids through differences in their vapor pressures. Known since antiquity, the concentration of alcohol by the application of heat to a fermented liquid mixture is perhaps the oldest form of distillation (see distilled beverages). However, the technique is now widely used for a variety of liquids in the chemical industry and in the production of petroleum products, among other fields, despite the fact it is energy-consuming. The liquid mixture evaporates, such that the vapor has a composition determined by the chemical properties of the mixture. Distillation of a given component is possible, if the vapor has a higher proportion of the given component than the mixture. This is caused by the given component having a higher vapor pressure — and thus a lower boiling point — than the other components. However, interactions between the components of the mixture can create properties unique to the mixture. Such interactions can result in an azeotrope. At an azeotrope, the mixture contains the given component in the same proportion as the vapor, so that evaporation does not change the purity, and distillation does not effect separation. For example, ethyl alcohol and water form an azeotrope of 95% at 78.2°C. By the nature of the process, it is theoretically impossible to completely purify the components using distillation, as distillation only tends to purity, never reaching it. This is comparable to dilution, which never reaches purity. If ultra-pure products are the goal, then further chemical separation must be used. The minimum in distillation is flash distillation, where either the temperature is rapidly increased or pressure reduced, and vapor and liquid fractions are thus obtained, which may be processed as such. The device used in distillation is referred to as a still and consists at a minimum of a reboiler (pot) in which the source material is heated, a condenser in which the heated vapor is cooled back to the liquid state, and a receiver in which the concentrated or purified liquid is collected. The equipment may affect separation by one of two main methods. Firstly the vapours given off by the heated mixture may consist of two liquids with significantly different boiling points. Thus, the vapour that is given off is in the vast majority of one or the other liquid, which after condensation and collection effects the separation. The second method (fractional distillation) is more effective at separating liquids with similar boiling points. This method relies upon a gradient of temperatures existing in the condenser stage of the equipment. Often in this technique, a vertical condenser, or column, is used. By extracting products that are liquid at different heights up the column, it is possible to extract liquids that have different boiling points. The greater the distance over which the temperature gradient in the condenser is applied leads to easier and more complete separation. It is also possible to separate fractions by cooling, using differences in their freezing points. In the American vernacular, this was known as 'jacking'. The most popular drink produced by this process during Colonial times was applejack, which was fermented apple cider that was then frozen in the winter months, and for which the liquid (containing the most alcohol) would be poured off to make applejack, with the result of approximately doubling the alcohol content of the resulting beverage. Many countries tax distilled alcohol, and preserve government income by legal restrictions on the use of a still. Distillation was developed into its modern form with the invention of the alembic by Arab-Yemeni (Iranian-born) alchemist Jabir ibn Hayyan c. 800; he is also credited with the invention of numerous other chemical apparatus and processes that are still in use today. Chemists often use distillation in their work as a means of separating compounds or components. A distillation apparatus sometimes used by chemists is a rotary evaporator to distill (or evaporate) away solvent from a mixture.

External links

- [http://www.agcom.purdue.edu/AgCom/Pubs/AE/AE-117.html Alcohol distillation]
- [http://homedistiller.org Homedistiller.org - The mother of all home distilling information websites]
- [http://homedistiller.org/wiki/index.php Alcohol Wiki at Homedistiller.org]
- [http://www.brewhaus.com Brewhaus.com - Homebrewing & Distilling Supplies]
- [http://www.schnaps.co.at/index_en.htm Schnapps.co.at - Schnapps Distilling for Hobby]
- [http://www.moonshine-still.com/ Moonshine-still.com - Building a World Class Home Distillation Apparatus]
- [http://olliver.family.gen.nz/schnapps.htm Brewing Real Schnaps Without A Still]
- [http://www.oilganic.com/essential-oils-distillation.htm Essential and Fragrance Oils Distillation] Category:Alchemical processes ja:蒸留

Process

Process (lat. processus - movement) is a naturally occurring or designed sequence of operations or events, possibly taking up time, space, expertise or other resource, which produces some outcome. A process may be identified by the changes it creates in the properties of one or more objects under its influence. Compare: project. See also: process management, process theory, and :Category:Nature.

Examples

A process may be categorized as singular, recurrent, or periodic. A singular process would be one which occurs only once. Few processes in nature can be considered singular. Most processes found in nature are recurrent, or repeat more than once. Recurring processes which repeat at a constant rate are considered periodic. The more periodic a process is the more useful it is as the basis of a clock. Below are a few specific examples of processes.
- The Bessemer process is a way of producing steel.
- The process of mining extracts ore.
- Evolution is a natural process which explains the adaptation of species over long peroids of time. (generally assumed to be an example of a recurrent process)
- The creation of the universe by God would be an example of a divine process. (generally assumed to be a singular process)
- Process music
- Civic governance and conflict resolution
- Error correction in the information processing of a stream of data.
- Protein biosynthesis

Art

See process music and Sol Lewitt.

Business

Businesses organize interactions by means of business processes.

Computing

Computing has many concepts of process.

Program execution

In computing, a computer process is a running instance of a program, including all variables and other states. A multitasking operating system switches between processes to give the appearance of simultaneous execution, though in fact, in general, only one process can be executing per CPU core. Some new processors, such as Intel's Pentium 4 with Hyperthreading capability, can actually execute two proceses at a time, because some parts of the core are doubled. More companies announced development of multicore processors.

Software development

A software development process is a sequence of steps that practitioners and managers take to create software. The steps usually include requirements analysis, programming, testing, and other steps. Different processes mix the steps together in different ways, and assign responsibility to people in different ways. The CMM is a meta-process that defines rigid goals up front, and emphasizes scientific management. Some dislike its emphasis on paperwork. Agile processes take the opposite approach, making things flexible. In SSADM a process is a part of a data flow diagram, and represents an action performed on the data.

Information system development

In the context of Information System Development a process is performed to produce a product. Such processes are also called techniques. Products represent what shall be constructed, e.g. class diagrams, state charts, and so on. Processes (techniques) are the procedures which describe in what order the construction of the products shall be performed, e.g. “at first, identify classes and objects” to construct a class diagram, “identify states”, and so on. In [Rolland1993] the term process is defined as “a related set of activities conducted to the specific purpose of product definition”. Both together, the set of products and their corresponding processes/techniques form a Method [Saeki] [Rolland1998]. Processes of the same nature are classified together into a Process Model.

References

[Rolland1993]	C. Rolland. Modeling the Requirements Engineering Process, 3rd European-Japanese Seminar on Information Modelling and Knowledge Bases, Budapest, Hungary, June 1993.
[Rolland1998]	C. Rolland. A Comprehensive View of Process Engineering. Proceedings of the 10th International Conference CAiSE'98, B. Lecture Notes in Computer Science 1413, Pernici, C. Thanos (Eds), Springer. Pisa, Italy, June 1998
[Saeki]	M. Saeki. CAME: The First Step to Automated Method Engineering

Engineering

Chemical engineering

A chemical process is a series of unit operations used to produce a material in large quantities. In the chemical industry, chemical engineers will use the following to define or illustrate a process:
- Process Flow Diagram (PFD)
- Piping and Instrumentation Diagram (P&ID)
- Simplified Process Description
- Detailed Process Description

Philosophy

In philosophy and systems theory, basic processes, or logical homologies as they were termed by Ludwig von Bertalanffy, are unifying principles which operate in many different systemic contexts. For example, feedback is a principle that figures prominently in the science of cybernetics. Natural and industrial processes utilize basic processes such as feedback. There is a philosophical system known as process philosophy, created by Alfred North Whitehead; related to this is process theology.

References

- Ludwig von Bertalanffy, General System Theory, George Braziller, New York, 1968, pages 84,85 ISBN 0807604534

External links

- [http://pespmc1.vub.ac.be/PROCESS.html Article defining process in Principia Cybernetica Web]

Processes in Science

Any method (or event) that results in a transformation in a physical or biological object, a substance or an organism, is a process in science. Some example of such processes are: activation, combustion, crystallization, centrifugation, diffraction, dispersion, distillation, electrolysis, electrophoresis, emulsification, evaporation, hydrolysis, nuclear fission, nuclear fusion, oxidation, phosphorescence, pyrolysis, reduction, reflection, refraction, scattering, sedimentation, sublimation are examples of common processes in physical sciences. Similarly, birth, cell division, fermentation, fertilization, germination, growth, geotropism, heliotropism, hybridization, metamorphosis, photosynthesis, transpiration are a few examples of biological processess.

Alcohol

In general usage, alcohol (from Arabic al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). This sense underlies the term alcoholism (addiction to alcohol). Other forms of alcohol are usually described with a clarifying adjective, as in isopropyl alcohol or by the suffix -ol, as in isopropanol. In chemistry, alcohol is a more general term, applied to any organic compound in which a hydroxyl group (-O H) is bound to a carbon atom, which in turn is bound to other hydrogen and/or carbon atoms. The general formula for a simple acyclic alcohol is C_nH_2n+1OH. As a drug, common alcohol (ethanol) is known to have a depressing effect that decreases the responses of the central nervous system.

Structure

central nervous system The functional group of an alcohol is a hydroxyl group bonded to an sp³ hybridized carbon. It can therefore be regarded as a derivative of water, with an alkyl group replacing one of the hydrogens. If an aryl group is present rather than an alkyl, the compound is generally called a phenol rather than an alcohol. The oxygen in an alcohol has a bond angle of around 109° (c.f. 104.5° in water), and two nonbonded electron pairs. The O-H bond in methanol (CH₃OH) is around 96 picometres long.

Primary, secondary, and tertiary alcohols

There are three major subsets of alcohols- 'primary' (1°), 'secondary' (2°) and 'tertiary' (3°), based upon the number of carbons the C-OH carbon (shown in red) is bonded to. Methanol is the simplest 'primary' alcohol. The simplest secondary alcohol is isopropanol (propan-2-ol), and a simple tertiary alcohol is tert-butanol (2-methylpropan-2-ol). butanol

Methanol & ethanol

The simplest and most commonly used alcohols are methanol and ethanol (common names methyl alcohol and ethyl alcohol, respectively), which have the structures shown above. Methanol was formerly obtained by the distillation of wood, and was called "wood alcohol". It is now a cheap commodity chemical produced by the high pressure reaction of carbon monoxide with hydrogen. In common usage, "alcohol" often refers simply to ethanol or "grain alcohol". Methylated spirits ("Meths"), also called "surgical spirits", is a form of ethanol rendered undrinkable by the addition of methanol. Aside from its major use in alcoholic beverages, ethanol is also used (though highly controlled) as an industrial solvent and raw material.

Uses

Alcohols are in wide use in industry and science as reagents, solvents, and fuels. Ethanol and methanol can be made to burn more cleanly than gasoline or diesel. Because of its low toxicity and ability to dissolve non-polar substances, ethanol is often used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla. In organic synthesis, alcohols frequently serve as versatile intermediates. Ethanol is also commonly used in beverages after fermentation to promote flavor or induce a euphoric intoxication commonly known as "drunkenness" or "being drunk". The use of ethanol for this purpose is illegal in some jurisdictions.

Sources

Many alcohols can be created by fermentation of fruits or grains with yeast, but only ethanol is commercially produced this way, chiefly for fuel and drink. Other alcohols are generally produced by synthetic routes from natural gas, petroleum, or coal feed stocks, for example via acid catalyzed hydration of alkenes. For more details see Chemistry of alcohols

Nomenclature

Systematic names

In the IUPAC system, the name of the alkane chain loses the terminal "e" and adds "ol", e.g. "methanol" and "ethanol". When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the "ol": propan-1-ol for CH₃CH₂CH₂OH, propan-2-ol for CH₃CH(OH)CH₃. Sometimes, the position number is written before the IUPAC name: 1-propanol and 2-propanol. If a higher priority group is present (such as an aldehyde, ketone or carboxylic acid), then it is necessary to use the prefix "hydroxy", for example: 1-hydroxy-2-propanol (CH₃COCH₂OH). Some examples of simple alcohols and how to name them: carboxylic acid Common names for alcohols usually take the name of the corresponding alkyl group and add the word "alcohol", e.g. methyl alcohol, ethyl alcohol or tert-butyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol depending on whether the hydroxyl group is bonded to the 1st or 2nd carbon on the propane chain. Isopropyl alcohol is also occasionally called sec-propyl alcohol. As mentioned above alcohols are classified as primary (1°), secondary (2°) or tertiary (3°), and common names often indicate this in the alkyl group prefix. For example (CH₃)₃COH is a tertiary alcohol is commonly known as tert-butyl alcohol. This would be named 2-methylpropan-2-ol under IUPAC rules, indicating a propane chain with methyl and hydroxyl groups both attached to the middle (#2) carbon. An alcohol with two hydroxyl groups is commonly called a "glycol", e.g. HO-CH₂-CH₂-OH is ethylene glycol. The IUPAC name is ethane-1,2-diol, "diol" indicating two hydroxyl groups, and 1,2 indicating their bonding positions. Geminal glycols (with the two hydroxyls on the same carbon atom), such as ethane-1,1-diol, are generally unstable. For three or four groups, "triol" and "tetraol" are used.

Etymology

The word "alcohol" almost certainly comes from the Arabic language (the "al-" prefix being the Arabic definite article); however, the precise origin is unclear. It was introduced into Europe, together with the art of distillation and the substance itself, around the 12th century by various European authors who translated and popularized the discoveries of Islamic alchemists. A popular theory, found in many dictionaries, is that it comes from الكحل = ALKHL = al-kuhul, originally the name of very finely powdered antimony sulfide Sb₂S₃ used as an antiseptic and eyeliner. The powder is prepared by sublimation of the natural mineral stibnite in a closed vessel. According to this theory, the meaning of alkuhul would have been first extended to distilled substances in general, and then narrowed to ethanol. This conjectured etymology has been circulating in England since 1672 at least (OED). However, this derivation is suspicious since the current Arabic name for alcohol, الكحول = ALKHWL = al???, does not derive from al-kuhul. The Qur'an in verse 37:47 uses the word الغول = ALGhWL = al-ghawl — properly meaning "spirit" ("spiritual being") or "demon" — with the sense "the thing that gives the wine its headiness". The word al-ghawl also originated the English word "ghoul", and the name of the star Algol. This derivation would, of course, be consistent with the use of "spirit" or "spirit of wine" as synonymous of "alcohol" in most Western languages. (Incidentally, the etymology "alcohol" = "the devil" was used in the 1930s by the U.S. Temperance Movement for propaganda purposes.) According to the second theory, the popular etymology and the spelling "alcohol" would not be due to generalization of the meaning of ALKHL, but rather to Western alchemists and authors confusing the two words ALKHL and ALGhWL, which have indeed been transliterated in many different and overlapping ways.

Physical and chemical properties

The hydroxyl group generally makes the alcohol molecule polar. Those groups can form hydrogen bonds to one another and to other compounds. Two opposing solubility trends in alcohols are: the tendency of the polar OH to promote solubility in water, and of the carbon chain to resist it. Thus, methanol, ethanol, and propanol are miscible in water because the hydroxyl group wins out over the short carbon chain. Butanol, with a four-carbon chain, is moderately soluble because of a balance between the two trends. Alcohols of five or more carbons (Pentanol and higher) are effectively insoluble because of the hydrocarbon chain's dominance. Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers. All simple alcohols are miscible in organic solvents. This hydrogen bonding means that alcohols can be used as protic solvents. The lone pairs of electrons on the oxygen of the hydroxyl group also makes alcohols nucleophiles. Alcohols, like water, can show either acidic or basic properties at the O-H group. With a pK_a of around 16-19 they are generally slightly weaker acids than water, but they are still able to react with strong bases such as sodium hydride or reactive metals such as sodium. The salts that result are called alkoxides, with the general formula RO^- M⁺. Meanwhile the oxygen atom has lone pairs of nonbonded electrons that render it weakly basic in the presence of strong acids such as sulfuric acid. For example, with methanol: sulfuric acid Alcohols can also undergo oxidation to give aldehydes, ketones or carboxylic acids, or they can be dehydrated to alkenes. They can react to form ester compounds, and they can (if activated first) undergo nucleophilic substitution reactions. For more details see the #Chemistry of alcohols section below.

Toxicity

Alcohols often have an odor described as 'biting' that 'hangs' in the nasal passages. Ethanol in the form of alcoholic beverages has been consumed by humans since pre-historic times, for a variety of hygienic, dietary, medicinal, religious, and recreational reasons. While infrequent consumption of ethanol in small quantities may be harmless or even beneficial, larger doses result in a state known as drunkenness or intoxication and, depending on the dose and regularity of use, can cause acute respiratory failure or death and with chronic use has medical repercussions. Other alcohols are substantially more poisonous than ethanol, partly because they take much longer to be metabolized, and often their metabolism produces even more toxic substances. Methanol, or wood alcohol, for instance, is oxidized by alcohol dehydrogenase enzymes in the liver to the poisonous formaldehyde, which can cause blindness or death. Interestingly, an effective treatment to prevent formaldehyde toxicity after methanol ingestion is to administer ethanol. This will bind to alcohol dehydrogenase, preventing methanol from binding and thus acting as a substrate. Any formaldehyde will be converted to formic acid and excreted before it causes damage.

Chemistry of alcohols

Preparation

Laboratory

There are three common methods:
- From alkyl halides: react with aqueous NaOH or KOH (mainly 1° alcohols). :R-Br + KOH → R-OH + KBr
- From aldehydes or ketones: reduction with sodium borohydride or lithium aluminium hydride. :R-CHO - [O] → R-OH
- From alkenes: an acid catalysed hydration reaction using concentrated sulfuric acid as a catalyst (gives usually 2° or 3° alcohols). :C₂H₄ + H₂SO₄ (l) → C₂H₅-HSO₄ :C₂H₅-HSO₄ + H₂O → C₂H₅OH + H₂SO₄ The formation of a secondary alcohol via the last two methods is shown: sulfuric acid

Industrial

- Fermentation: using glucose produced from sugar from the hydrolysis of starch, in the presence of yeast and temperature of <37°C to produce ethanol. :C₁₂H₂₂O₁₁ → C₆H₁₂O₆ + C₆H₁₂O₆ :Invertase → glucose + fructose :C₆H₁₂O₆ + H₂O → C₂H₅OH + CO₂ :Glucose → zymase + ethanol
- Direct hydration: using ethene or other alkenes from cracking of fractions of distilled crude oil. Uses a catalyst of phosphoric acid under high temperature and pressure.
- Methanol from water gas: It is manufactured from synthesis gas, where CO + 2 H₂ are combined to produce methanol using a Cu, ZnO and Al₂O₃ catalyst at 250°C and a pressure of 50-100 atm. :[CO + H₂] + H₂O (g) → CH₃OH

Reactions

See the physical and chemical properties section above for a general overview.

Deprotonation

Alcohols can behave as weak acids, undergoing deprotonation. The deprotonation reaction to produce an alkoxide salt is either performed with a strong base such as sodium hydride or n-butyllithium, or with sodium or potassium metal. : 2 R-OH + 2 NaH → 2 R-O^-Na⁺ + H₂↑ : 2 R-OH + 2Na → 2R-O⁻Na⁺ : e.g. 2 CH₃CH₂-OH + 2 Na → 2 CH₃-CH₂-O⁻Na⁺ Water is similar in pK_a to many alcohols, so with sodium hydroxide there is an equilibrium set up which usually lies to the left: : R-OH + NaOH <=> R-O^-Na⁺ + H₂O (equilibrium to the left)

Nucleophilic substitution

The OH group is not a good leaving group in nucleophilic substitution reactions, so neutral alcohols do not react in such reactions. However if the oxygen is first protonated to give R−OH₂⁺, the leaving group (water) is much more stable, and nucleophilic substitution can take place. For instance, tertiary alcohols react with hydrochloric acid to produce tertiary alkyl halides, where the hydroxyl group is replaced by a chlorine atom. If primary or secondary alcohols are to be reacted with hydrochloric acid, an activator such as zinc chloride is needed. Alternatively the conversion may be performed directly using thionyl chloride.^[1] thionyl chloride Alcohols may likewise be converted to alkyl bromides using hydrobromic acid or phosphorus tribromide, for example: : 3 R-OH + PBr₃ → 3 RBr + H₃PO₃ In the Barton-McCombie deoxygenation an alcohol is deoxygenated to an alkane with tributyltin hydride or a trimethylborane-water complex in a radical substitution reaction.

Dehydration

Alcohols are themselves nucleophilic, so R−OH₂⁺ can react with ROH to produce ethers and water, although this reaction is rarely used except in the manufacture of diethyl ether. More useful is the E1 elimination reaction of alcohols to produce alkenes. The reaction generally obeys Zaitsev's Rule, which states that the most stable (usually the most substituted) alkene is formed. Tertiary alcohols eliminate easily at just above room temperature, but primary alcohols requre a higher temperature. This is a diagram of acid catalysed dehydration of ethanol to produce ethene: 550px

Esterification

To form an ester from an alcohol and a carboxylic acid the reaction, known as "Fischer esterification", is usually performed at reflux with a catalyst of concentrated sulfuric acid: : R-OH + R'-COOH

\Leftrightarrow

R'-COOR + H₂O In order to drive the equilibrium to the right and produce a good yield of ester, water is usually removed, either by an excess of H₂SO₄ or by using a Dean-Stark apparatus. Esters may also be prepared by reaction of the alcohol with an acid chloride in the presence of a base such as pyridine. Other types of ester are prepared similarly- for example p-toluenesulfonate (tosylate) esters are made by reaction of the alcohol with p-toluenesulfonyl chloride in pyridine.

Oxidation

Primary alcohols generally give aldehydes or carboxylic acids upon oxidation, while secondary alcohols give ketones. Traditionally strong oxidants such as the dichromate ion or potassium permanganate are used, under acidic conditions, for example: :3 CH₃-CH(-OH)-CH₃ + K₂Cr₂O₇ + 4 H₂SO₄ → 3 CH₃-C(=O)-CH₃ + Cr₂(SO₄)₃ + K₂SO₄ + 7 H₂O Frequently in aldehyde preparations these reagents cause a problem of over-oxidation to the carboxylic acid. To avoid this, other reagents such as PCC, Dess-Martin periodinane, IBX acid, TPAP or methods such as Swern oxidation are now preferred. Alcohols with a methyl group attached to the alcohol carbon can also undergo a haloform reaction (such as the iodoform reaction) in the presence of the halogen and a base such as sodium hydroxide. Tertiary alcohols resist oxidation, but can be oxidised by reagents such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.

External links

- [http://www.french-paradox.net/fpbksb1.html What Is Alcohol, Anyway?] Interesting information about alcohols.
- Category:Drugs Category:Antiseptics Category:Arabic words Category:functional groups ja:アルコール simple:Alcohol

Chemical industry

Chemical industry includes those industries involved in the production of petrochemicals, agrochemicals, pharmaceuticals, polymers, paints, oleochemicals etc. Chemical processes are used, including chemical reactions to form new substances, separations based on properties such as solubility or ionic charge, and distillations, in addition to transformations by heating and other methods. Chemical industries involve the processing of, or change in, raw materials obtained by mining, and agriculture among other supply sources, into materials and substances that are useful on their own, or in other industries. The food-processing industries are generally not included in the term "chemical industry".

Companies

The biggest companies in chemical industry on earth (business volume in billion Euros)
- Badische Anilin- und Soda-Fabrik (BASF)(D) 28 (formerly IG-Farben)
- Dow Chemical (USA) 27
- DuPont (USA) 24
- Bayer (D) 20 (formerly IG-Farben)
- ExxonMobil Chemicals (USA) 20 (formerly Standard Oil)
- Atofina (F) 20
- BP Chemicals (GB) 13
- Mitsubishi Chemicals (J) 12
- Deutsche Gold- und Silber-Scheide-Anstalt (DEGUSSA)(D) 11(formerly IG-Farben)
- Shell Chemicals (NL/GB) 11 Category:Chemistry Category:Industries ja:化学工業

Petroleum

]] Petroleum (from Latin petra – rock and oleum – oil), crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish liquid. A widely believed myth is that the oil itself is flammable; however, it is actually the gas that evaporates from the oil that is flammable. Petroleum exists in the upper strata of some areas of the Earth's crust. Another name is naphtha, from Persian naft or nafátá (to flow). It consists of a complex mixture of various hydrocarbons, largely of the alkane series, but may vary much in appearance, composition, and purity. Petroleum is used mostly, by volume, for producing fuel oil, which is an important "primary energy" source ([http://www.iea.org/bookshop/add.aspx?id=144 IEA Key World Energy Statistics]). Petroleum is also the raw material for many chemical products, including solvents, fertilizers, pesticides, and plastics.

Origin

Biogenic theory

Most geologists view crude oil, like coal and natural gas, as the product of compression and heating of ancient vegetation over geological time scales. According to this theory, it is formed from the decayed remains of prehistoric marine animals and terrestrial plants. Over many centuries this organic matter, mixed with mud, is buried under thick sedimentary layers of material. The resulting high levels of heat and pressure cause the remains to metamorphose, first into a waxy material known as kerogen, and then into liquid and gaseous hydrocarbons in a process known as catagenesis. These then migrate through adjacent rock layers until they become trapped underground in porous rocks called reservoirs, forming an oil field, from which the liquid can be extracted by drilling and pumping. 150 °C is generally considered the "oil window". Though this corresponds to different depths for different locations around the world, a 'typical' depth for an oil window might be 4 - 5 km. Three conditions must be present for oil reservoirs to form: a rich source rock, a migration conduit, and a trap (seal) that forms the reservoir. The reactions that produce oil and natural gas are often modeled as first order breakdown reactions, where kerogen breaks down to oil and natural gas by a large set of parallel reactions, and oil eventually breaks down to natural gas by another set of reactions.

Abiogenic Theory

The idea of abiogenic petroleum origin was championed in the Western world by Thomas Gold based on thoughts from Russia, mainly on studies of Nikolai Kudryavtsev. The idea proposes that large amounts of carbon exist naturally in the planet, some in the form of hydrocarbons. Hydrocarbons are less dense than aqueous pore fluids, and migrate upward through deep fracture networks. Thermophilic, rock-dwelling microbial life-forms are in part responsible for the biomarkers found in petroleum. However, their role in the formation, alteration, or contamination of the various hydrocarbon deposits is not yet understood. Thermodynamic calculations and experimental studies confirm that n-alkanes (common petroleum components) do not spontaneously evolve from methane at pressures typically found in sedimentary basins, and so the theory of an abiogenic origin of hydrocarbons suggests deep generation (below 200 km) (see results [http://www.gasresources.net/]). As with any petroleum, the idea goes, these hydrocarbons would migrate upwards with methane, sometimes bearing helium and nitrogen and frequently heavy metals such as Nickel, Vanadium, Arsenic, Lead, Cadmium, Copper, Zinc, Mercury and others. Diamondoids are common in oil and gas and its nature probably is related to natural diamonds that come from earth's mantle. The proponents of abiogenic petroleum claim that reserves are never exhausted because they are filled from below. This idea has not been supported by any critically reviewed research. It has been widely discredited by scientists and geologists alike. Also, even if oil fields can be replenished from abiotic deposits that exist deeper within the earth, it would be very near impossible that they could be replenished at current rates of depletion, future rates aside. It would certainly take many thousands if not millions of years for oil fields to regain original levels.

Composition

In refining, the component chemicals of petroleum are separated by fractional distillation, which is a separation based on relative boiling points (or equivalently relative volatility). The different products (in order of boiling points) include light gases (e.g. methane, ethane, propane), gasoline, jet fuel, kerosene, diesel, gasoil, paraffin wax, and asphalt. Subtler techniques, such as gas chromatography, HPLC, and GC-MS, can separate some fractions of petroleum into individual compounds; these are analytical chemistry methods used mainly in quality control in refineries. Strictly speaking, petroleum consists of hydrocarbons (compounds of hydrogen and carbon) and non-hydrocarbon fractions, which might also include nitrogen, sulfur, oxygen, or traces of metals such as vanadium or nickel, such elements often constituting less than 1% of the whole. The four lightest alkanes — CH₄ (methane), C₂H₆ (ethane), C₃H₈ (propane) and C₄H₁₀ (butane) — are all gases, boiling at -161.6 °C, -88.6 °C, -42 °C, and -0.5 °C, respectively (-258.9°, -127.5°, -43.6°, and +31.1° F). Crude oil is non-polar. The chains in the C_5-7 range are all light, easily vaporized, clear naphthas. They are used as solvents, dry cleaning fluids, and other quick-drying products. The chains from C₆H₁₄ through C₁₂H₂₆ are blended together and used for gasoline. Kerosene is made up of chains in the C₁₀ to C₁₅ range, followed by diesel fuel/heating oil (C₁₀ to C₂₀) and heavier fuel oils as the ones used in ship engines. These petroleum compounds are all liquid at room temperature. Lubricating oils and semi-solid greases (including Vaseline®) range from C₁₆ up to C₂₀. Chains above C₂₀ form solids, starting with paraffin wax, then tar and asphaltic bitumen. Boiling ranges of petroleum atmospheric pressure distillation fractions in degrees Celsius:
- petrol ether: 40 - 70 °C (used as solvent)
- light petrol: 60 - 100 °C (gasoline)
- heavy petrol: 100 - 150 °C (automobile fuel)
- light kerosene: 120 - 150 °C (household solvent and fuel)
- kerosene: 150 - 300 °C (jet fuel)
- gasoil: 250 - 350 °C (diesel fuel/heating oil)
- lubrication oil: > 300 °C (engine oil)
- remaining fractions: tar, asphalt, residual fuel

Extraction

Generally the first stage in the extraction of crude oil is to drill a well into the underground reservoir. Historically, in the USA some oil fields existed where the oil rose naturally to the surface, but most of these fields have long since been depleted, except for certain remote locations in Alaska. Often many wells (called multilateral wells) will be drilled into the same reservoir, to ensure that the extraction rate will be economically viable. Also, some wells (secondary wells) may be used to pump water, steam, acids or various gas mixtures into the reservoir to raise or maintain the reservoir pressure, and so maintain an economic extraction rate. If the underground pressure in the oil reservoir is sufficient, then the oil will be forced to the surface under this pressure. Gaseous fuels or natural gas are usually present, which also supplies needed underground pressure. In this situation it is sufficient to place a complex arrangement of valves (the Christmas tree) on the well head to connect the well to a pipeline network for storage and processing. This is called primary oil recovery. Usually, only about 20% of the oil in a reservoir can be extracted this way. Over the lifetime of the well the pressure will fall, and at some point there will be insufficient underground pressure to force the oil to the surface. If economical, and it often is, the remaining oil in the well is extracted using secondary oil recovery methods (see: energy balance and net energy gain). Secondary oil recovery uses various techniques to aid in recovering oil from depleted or low-pressure reservoirs. Sometimes pumps, such as beam pumps and electrical submersible pumps (ESPs), are used to bring the oil to the surface. Other secondary recovery techniques increase the reservoir's pressure by water injection, natural gas reinjection and gas lift, which injects air, carbon dioxide or some other gas into the reservoir. Together, primary and secondary recovery allow 25% to 35% of the reservoir's oil to be recovered. Tertiary oil recovery reduces the oil's viscosity to increase oil production. Tertiary recovery is started when secondary oil recovery techniques are no longer enough to sustain production, but only when the oil can still be extracted profitably. This depends on the cost of the extraction method and the current price of crude oil. When prices are high, previously unprofitable wells are brought back into production and when they are low, production is curtailed. Thermally-enhanced oil recovery methods (TEOR) are tertiary recovery techniques that heat the oil and make it easier to extract. Steam injection is the most common form of TEOR, and is often done with a cogeneration plant. In this type of cogeneration plant, a gas turbine is used to generate electricity and the waste heat is used to produce steam, which is then injected into the reservoir. This form of recovery is used extensively to increase oil production in the San Joaquin Valley, which has very heavy oil, yet accounts for 10% of the United States' oil production. In-situ burning is another form of TEOR, but instead of steam, some of the oil is burned to heat the surrounding oil. Occasionally, detergents are also used to decrease oil viscosity. Tertiary recovery allows another 5% to 15% of the reservoir's oil to be recovered.

Alternate means of producing oil

As oil prices continue to escalate, other alternatives to producing oil have been gaining importance. The most viable of these is the coal to oil process, known as the Fischer-Tropsch process, that aims to convert coal into crude oil. It was a concept pioneered in Nazi Germany when imports of petroleum were restricted due to war and Germany found a method to extract oil from coal. It was known as Ersatz ("substitute" in German), and accounted for nearly half the total oil used in WWII by Germany. However, the process was used only as a last resort as naturally occurring oil was much cheaper. As crude oil prices increase, the cost of coal to oil conversion becomes comparatively cheaper. The method involves converting high ash coal into synthetic oil in a multistage process. Ideally, a ton of coal produces nearly 200 liters of crude, with by-products ranging from tar to rare chemicals. Currently, two companies have commercialised their Fischer-Tropsch technology. [http://www.shell.com.my/smds Shell] in Bintulu, Malaysia, uses natural gas as a feedstock, and produces primarily low-sulfur diesel fuels. [http://www.sasol.com Sasol] in South Africa uses coal as a feedstock, and produces a variety of synthetic petroleum products. The process is today used in South Africa to produce most of the country's diesel fuel from coal by the company Sasol. The process was used in South Africa to meet its energy needs during its isolation under Apartheid. This process has received renewed attention in the quest to produce low sulfur diesel fuel in order to minimize the environmental impact from the use of diesel engines.

History

The first oil wells were drilled in China in the 4th century or earlier. They had depth of up to 800 feet and were drilled using bits attached to bamboo poles. The oil was burned to evaporate brine and produce salt. By the 10th century, extensive bamboo pipelines connected oil wells with salt springs. Ancient Persian tablets indicate the medicinal and lighting uses of petroleum in the upper echelons of their society. In the 8th century, the streets of the newly-constructed Baghdad were paved with tar, derived from easily-accessible petroleum from natural fields in the region. In the 9th century, oil fields were exploited in Baku, Azerbaijan, to produce naphtha. These fields were described by the geographer Masudi in the 10th century, and by Marco Polo in the 13th century, who described the output of those wells as hundreds of shiploads. (See also: Timeline of Islamic science and technology.) The modern history of oil began in 1853, with the discovery of the process of oil distillation. Crude oil was distilled into kerosene by Ignacy Lukasiewicz, a Polish scientist. The first "rock oil" ("petr-oleum") mine was created in Bobrka, near Krosno in southern Poland in the following year and the first refinery (actually a distillery) was built in Ulaszowice, also by Lukasiewicz. These discoveries rapidly spread around the world, and Meerzoeff built the first Russian refinery in the mature oil fields at Baku in 1861. 1861 by Russian engineer F.N. Semyenov, on the Aspheron Peninsula north-east of Baku.38]] The first commercial oil well drilled in North America was in Oil Springs, Ontario, Canada in 1858, dug by James Miller Williams. The American petroleum industry began with Edwin Drake's discovery of oil in 1859, near Titusville, Pennsylvania. The industry grew slowly in the 1800s, driven by the demand for kerosene and oil lamps. It became a major national concern in the early part of the 20th century; the introduction of the internal combustion engine provided a demand that has largely sustained the industry to this day. Early "local" finds like those in Pennsylvania and Ontario were quickly exhausted, leading to "oil booms" in Texas, Oklahoma, and California. By 1910, significant oil fields had been discovered in Canada (specifically, in the province of Alberta), the Dutch East Indies (1885, in Sumatra), Persia (1901, in Masjed Soleiman), Peru, Venezuela, and Mexico, and were being developed at an industrial level. Even until the mid-(1950s), coal was still the world's foremost fuel, but oil quickly took over. Following the 1973 energy crisis and the 1979 energy crisis there was significant media coverage of oil supply levels. This brought to light the concern that oil is a limited resource that will eventually run out, at least as an economically viable energy source. At the time, the most common and popular predictions were always quite dire, and when they did not come true, many dismissed all such discussion. The future of petroleum as a fuel remains somewhat controversial. USA Today news (2004) reports that there are 40 years of petroleum left in the ground. Some would argue that because the total amount of petroleum is finite, the dire predictions of the 1970s have merely been postponed. Others argue that technology will continue to allow for the production of cheap hydrocarbons and that the earth has vast sources of unconventional petroleum reserves in the form of tar sands, bitumen fields and oil shale that will allow for petroleum use to continue for an extremely long period in the future. Today, about 90% of vehicular fuel needs are met by oil. Petroleum also makes up 40% of total energy consumption in the United States, but is responsible for only 2% of electricity generation. Petroleum's worth as a portable, dense energy source powering the vast majority of vehicles and as the base of many industrial chemicals makes it one of the world's most important commodities. Access to it was a major factor in several military conflicts, including World War II and the Persian Gulf War. About 80% of the world's readily accessible reserves are located in the Middle East, with 62.5% coming from the Arab 5: Saudi Arabia (12.5%), UAE, Iraq, Qatar and Kuwait. The USA has less than 3%.

Environmental effects

The presence of oil has significant social and environmental impacts, from accidents and routine activities such as seismic exploration, drilling, and generation of polluting wastes. Oil extraction is costly and sometimes environmentally damaging, although Dr. John Hunt from Woods Hole pointed out in a 1981 paper that over 70% of the reserves in the world are associated with visible macroseepages, and many oil fields are found due to natural leaks. Offshore exploration and extraction of oil disturbs the surrounding marine environment. Extraction may involve dredging, which stirs up the seabed, killing the sea plants that marine creatures need to survive. Crude oil and refined fuel spills from tanker ship accidents have damaged fragile ecosystems in Alaska, the Galapagos Islands, Spain, and many other places. Burning oil releases carbon dioxide into the atmosphere, which contributes to global warming. Per energy unit, oil produces less CO2 than coal, but more than natural gas. However, oil's unique role as a transportation fuel makes reducing its CO₂ emissions a particularly thorny problem; amelioration strategies such as carbon sequestering are generally geared for large power plants, not individual tailpipes. Renewable energy source alternatives do exist, although the degree to which they can replace petroleum and the possible environmental damage they may cause are uncertain and controversial. Sun, wind, geothermal, and other renewable electricity sources cannot directly replace high energy density liquid petroleum for transportation use; instead automobiles and other equipment must be altered to allow using electricity (in batteries) or hydrogen (via fuel cells or internal combustion) which can be produced from renewable sources. Other options include using biomass-origin liquid fuels (ethanol, biodiesel). Any combination of solutions to replace petroleum as a liquid transportation fuel will be a very large undertaking.

Future of oil

Main article: Hubbert Peak The Hubbert peak theory, also known as peak oil, is a theory concerning the long-term rate of production of conventional oil and other fossil fuels. It assumes that oil reserves are not replenishable (i.e. that abiogenic replenishment is negligible), and predicts that future world oil production must inevitably reach a peak and then decline as these reserves are exhausted. Controversy surrounds the theory, as predictions for when the global peak will actually take place are highly dependent on the past production and discovery data used in the calculation. The issue can be considered from the point of view of individual regions or of the world as a whole. Originally M. King Hubbert noticed that the discoveries in the United States had peaked in the early 1930s, and concluded that production would then peak in the early 1970s. His prediction turned out to be correct, and after the US peaked in 1971 - and thus lost its excess production capacity - OPEC was finally able to manipulate oil prices, which led to the oil crisis in 1973. Since then, most other countries have also peaked: Britain's North Sea, for example in late 1990s. China has confirmed that two of its largest producing regions are in decline, and Mexico's national oil company, Pemex, has announced that Cantarell Field, one of the world's largest offshore fields, is expected to peak in 2006, and then decline 14% per annum. For various reasons (perhaps most importantly the lack of transparency in accounting of global oil reserves), it is difficult to predict the oil peak in any given region. Based on available production data, proponents have previously (and incorrectly) predicted the peak for the world to be in years 1989, 1995, or 1995-2000. However these predictions date from before the recession of the early 1980s, and the consequent reduction in global consumption, the effect of which was to delay the date of any peak by several years. A new prediction by Goldman Sachs picks 2007 for oil and some time later for natural gas. Just as the 1971 U.S. peak in oil production was only clearly recognized after the fact, a peak in world production will be difficult to discern until production clearly drops off. One signal is that 2005 saw a dramatic fall in announced new oil projects coming to production from 2008 onwards. Since it takes on average four to six years for a new project to start producing oil, in order to avoid the peak, these new projects would have to not only make up for the depletion of current fields, but increase total production annually to meet increasing demand.

Classification

The oil industry classifies "crude" by the location of its origin (e.g., "West Texas Intermediate, WTI" or "Brent") and often by its relative weight (API gravity) or viscosity ("light", "intermediate" or "heavy"); refiners may also refer to it as "sweet", which means it contains relatively little sulfur, or as "sour", which means it contains substantial amounts of sulfur and requires more refining in order to meet current product specifications. The world reference barrels are:
- Brent Blend, comprising 15 oils from fields in the Brent and Ninian systems in the East Shetland Basin of the North Sea. The oil is landed at Sullom Voe terminal in the Shetlands. Oil production from Europe, Africa and Middle Eastern oil flowing West tends to be priced off the price of this oil, which forms a benchmark. See also Brent crude.
- West Texas Intermediate (WTI) for North American oil.
- Dubai used as benchmark for the Asia-Pacific region for Middle East Oil
- Tapis (from Malaysia, used as a reference for light Far East oil)
- Minas (from Indonesia, used as a reference for heavy Far East oil)
- The OPEC Basket consisting of
- Arab Light Saudi Arabia
- Bonny Light Nigeria
- Fateh Dubai
- Isthmus Mexico (non-OPEC)
- Minas Indonesia
- Saharan Blend Algeria
- Tia Juana Light Venezuela OPEC attempts to keep the price of the Opec Basket between upper and lower limits, by increasing and decreasing production. This makes the measure important for market analysts. The OPEC Basket, including a mix of light and heavy crudes, is heavier than both Brent and WTI. See also [http://tonto.eia.doe.gov/ask/crude_types1.html]

Pricing

Venezuela References to the oil price are usually either references to the spot price of either WTI/Light Crude as traded on New York Mercantile Exchange (NYMEX) for delivery in Cushing, Oklahoma; or the price of Brent as traded on the International Petroleum Exchange (IPE) for delivery at Sullom Voe. The price of a barrel of oil is highly dependent on both its grade (which is determined by factors such as its specific gravity or API and its sulphur content) and location. The vast majority of oil will not be traded on an exchange but on a over-the-counter basis, typically with reference to a marker crude oil grade that is typically quoted via the pricing agency Platts. For example in Europe a particular grade of oil, say Fulmar, might be sold at a price of "Brent plus US$0.25/barrel".or as an intra-company transaction. IPE claim that 65% of traded oil is priced off their Brent benchmarks. Other important benchmarks include Dubai, Tapis, and the OPEC basket. The Energy Information Administration (EIA) uses the Imported Refiner Acquisition Cost, the weighted average cost of all oil imported into the US as their "world oil price". It is often claimed that OPEC sets the oil price and the true cost of a barrel of oil is around $2, which is equivalent to the cost of extraction of a barrel in the Middle East. These estimates of costs ignore the cost of finding and developing oil reserves. Furthermore the important cost as far as price is concerned, is not the price of the cheapest barrel but the cost of producing the marginal barrel. By limiting production OPEC has caused more expensive areas of production such as the North Sea to be developed before the Middle East has been exhausted. OPEC's power is also often overstated. Investing in spare capacity is expensive and the low oil price environment in the late 90s led to cutbacks in investment. This has meant during the oil price rally seen between 2003-2005, OPEC's spare capacity has not been sufficient to stabilise prices. Energy Information Administration Oil demand is highly dependent on global macroeconomic conditions, so this is also an important determinant of price. Some economists claim that high oil prices have a large negative impact on the global growth. This means that the relationship between the oil price and global growth is not particularly stable although a high oil price is often thought of as being a late cycle phenomenon. A recent low point was reached in January 1999, after increased oil production from Iraq coincided with the Asian financial crisis, which reduced demand. The prices then rapidly increased, more than doubling by September 2000, then fell until the end of 2001 before steadily increasing, reaching US $40 to US $50 per barrel by September 2004. [http://futures.tradingcharts.com/chart/CO/M] In October 2004, light crude futures contracts on the NYMEX for November delivery exceeded US $53 per barrel and for December delivery exceeded US $55 per barrel. Crude oil prices surged to a record high above $60 a barrel in June 2005, sustaining a rally built on strong demand for gasoline and diesel and on concerns about refiners' ability to keep up. This trend continued into early August 2005, as NYMEX crude oil futures contracts surged past the $65 mark as consumers kept up the demand for gasoline despite its high price. (see Oil price increases of 2004 and 2005).) The New York Mercantile Exchange (NYMEX) trades crude oil (including futures contracts) and provides the basis of US crude oil pricing via WTI (West Texas Intermediate). Other exchanges also trade crude oil futures, eg the International Petroleum Exchange (IPE) in London trades contracts in Brent crude. International Petroleum Exchange See also [http://www.wtrg.com/prices.htm History and Analysis of Crude Oil Prices]

Top petroleum-producing countries

Source: [http://www.eia.doe.gov/emeu/cabs/topworldtables1_2.html Energy Statistics from the U.S. Government] (Ordered by amount (barrels per day) produced in 2004):
- Saudi Arabia (OPEC)
- Russia
- United States ¹
- Iran (OPEC)
- Mexico ¹
- China ¹
- Norway ¹
- Canada ¹
- Venezuela (OPEC) ¹
- United Arab Emirates (OPEC)
- Kuwait (OPEC)
- Nigeria (OPEC)
- United Kingdom ¹
- Iraq ¹ peak production already passed in this state peak production already passed in this state (Ordered by amount exported in 2003):
- Saudi Arabia (OPEC)
- Russia
- Norway ¹
- Iran (OPEC)
- United Arab Emirates (OPEC)
- Venezuela (OPEC) ¹
- Kuwait (OPEC)
- Nigeria (OPEC)
- Mexico ¹
- Algeria (OPEC)
- Libya (OPEC) ¹ ¹ peak production already passed in this state Note that the USA consumes almost all of its own production. Total world production/consumption (as of 2005) is approximately 84 million barrels per day. See also: Organization of Petroleum Exporting Countries.

External links

- [http://www.longemergency.blogspot.com Long Emergency Blog] - A site with Peak Oil news and discussion, regarding how our world will never be the same.
- [http://www.api.org/ American Petroleum Institute] - A site run by the American Petroleum Institute, the trade association of the US oil industry.
- [http://futures.tradingcharts.com/chart/CO Crude Oil Commodity Charts] - Price charts for crude oil
- [http://www.eia.doe.gov/oil_gas/petroleum/info_glance/petroleum.html US Energy Information Administration] - Part of the informative website of the US Government's Energy Information Administration.
- [http://www.geo.uw.edu.pl/BOBRKA/DATY/daty.htm Major dates of the Polish petroleum industry]
- [http://www.gasresources.net/DisposalBioClaims.htm Dismissal of the Claims of a Biological Connection for Natural Petroleum.]
- [http://www.aapg.org/explorer/2002/11nov/abiogenic.cfm Abiogenic Gas Debate 11:2002 (EXPLORER)]
- [http://www.gasresources.net/Introduction.htm An introduction to the modern petroleum science, and to the Russian-Ukrainian theory of deep, abiotic petroleum origins.]
- [http://www.spe.org/elibinfo/eLibrary_Papers/spe/1982/82UGR/00010836/00010836.htm Unconventional Ideas About Unconventional Gas (Society of Petroleum Engineers)]
- [http://www.bp.com/genericsection.do?categoryId=92&contentId=7005893 BP Statistical Revue of World Energy ]
- [http://www.nymex.com Nymex] - oil trading center of the US
- [http://www.bloomberg.com/energy/ Bloomberg Energy Prices] - current prices on world mercantile exchanges
- [http://www.oilmarketer.co.uk/ Oil Marketer] - oil news and market information
- [http://www.economist.com/surveys/displaystory.cfm?story_id=3884623 Oil in troubled waters] - Economist article on investor approaches to oil markets, supply, and future
- [http://www.pdvsa.com] - The site for the state-owned oil company of Venezuela, much of whose profits go to helping the poor of the country as well as others.
- [http://www.venezuelanalysis.com] - A site focusing on developments in Venezuela, with a big emphasis on the oil issue.

Articles

- [http://pr.caltech.edu/periodicals/CaltechNews/articles/v38/oil.html The End of the Age of Oil] - article adapted from a talk by Caltech vice provost and professor of physics David Goodstein
- [http://www.publicintegrity.org/oil/ The Politics of Oil] - A report on the oil industry's influence of lawmakers and public policy by the Center for Public Integrity.
- [http://news.bbc.co.uk/2/hi/business/3953907.stm BBC: Stability fears rise as oil reliance grows]
- [http://www.washingtonpost.com/wp-dyn/content/article/2005/06/09/AR2005060900148_pf.html Top Saudi Says Kingdom Has Plenty of Oil] "261 billion barrels in reserve..."
- [http://business.timesonline.co.uk/article/0,,16849-1733893,00.html Lee Raymond of Exxon Mobile believes oil supplies will rise]
- [http://www.arabnews.com/?page=6§ion=0&article=44011&d=29&m=4&y=2004 Known Saudi Arabian Oil Reserves Tripled]
- [http://www2.eluniversal.com.mx/pls/impreso/noticia.html?id_nota=6110&tabla=miami Pemex's oil estimates double:] Mexican Oil company's estimate of reserves doubled.
- [http://www.gasresources.net/DisposalBioClaims.htm Dismissal of the Claims of a Biological Connection for Natural Petroleum]
- [http://www.aapg.org/explorer/2002/11nov/abiogenic.cfm Abiogenic Gas Debate 11:2002 (EXPLORER)]

Data

- [http://www.eia.doe.gov/emeu/international/petroleu.html Department of Energy EIA - World supply and consumption]
- [http://www.eia.doe.gov/oil_gas/petroleum/info_glance/prices.html US petroleum prices]

References

# [http://www.pnas.org/cgi/content/full/99/17/10976 Article link] #

Books about the petroleum industry

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Writers covering the petroleum industry

- Colin J. Campbell
- Jay Hanson
- Kenneth S. Deffeyes
- David Goodstein
- Daniel Yergin
- Thomas Gold Category:Lubricants Category:Petroleum Category:Oils ko:석유 ja:石油

Azeotrope

An azeotrope is a liquid mixture of two or more components which has a unique constant boiling point. An azeotrope may boil at a higher, lower, or intermediate temperature relative to the constituent liquids, and the liquid retains the same composition as it is boiled. As a consequence, the vapor has the same composition as the liquid and simple distillation will not separate the constituents as it would with most liquid mixtures; to get a higher concentration it is necessary to use azeotropic distillation. The word azeotrope comes from the Greek "zein tropos", or "constant boiling". An azeotrope is said to be positive if the constant boiling point is at a temperature maximum, and negative when the boiling point is at a temperature minimum. The vast majority of azeotropes are minimum boiling. All liquid mixtures which are immiscible and which form azeotropes are minimum boiling .

Examples of Azeotropes

- nitric acid (67.4%) / water, boils at 121°C
- perchloric acid (28.4%) / water, boils at 203°C (negative azeotrope)
- hydrofluoric acid (35.6%) / water, boils at 111.35°C (negative azeotrope)
- ethanol (96%) / water, boils at 78.2°C
- sulfuric acid (98.3%) / water, boils at 100°C
- acetone / methanol / chloroform form an intermediate boiling azeotrope
- diethyl ether (33%) / halothane (66%) a mixture once commonly used in anaesthesia.

External links

- [http://eweb.chemeng.ed.ac.uk/chem_eng/azeotrope_bank.html Azeotrope Databank]
- Update in Anaesthesia: The halothane/ether azeotrope - A reconsideration [http://www.nda.ox.ac.uk/wfsa/html/u18/u1811_01.htm] Category:Fluid dynamics

Water (molecule)

Water has the chemical formula H₂O, meaning that one molecule of water is composed of two hydrogen atoms and one oxygen atom. It is in dynamic equilibrium between the liquid and solid states at standard temperature and pressure. At room temperature, it is a nearly colorless, tasteless, and odorless liquid. It is often referred to in the sciences as the universal solvent and the only pure substance found naturally in all three states of matter.

Forms of water

:See the :Category:Forms of water Water may take many forms. The solid state of water is commonly known as ice (while many other forms exist, see amorphous solid water; the gaseous state is known as water vapor (or steam), and the common liquid phase is generally taken as simply water. Water may take many forms, and is the base molecule of aqueous solutions. Above a certain critical temperature and pressure (647 K and 22.064 MPa), water molecules assume a supercritical condition, in which liquid-like clusters float within a vapor-like phase. Heavy water is water in which the hydrogen atoms are replaced by its heavier isotope, deuterium. It is chemically almost identical to normal water. Heavy water is used in the nuclear industry to slow down neutrons.

A common substance

Water in the Universe

Water has been found in interstellar clouds within our galaxy, the Milky Way. It is believed that water exists in abundance in other galaxies too, because its components, hydrogen and oxygen, are among the most abundant elements in the universe. Interstellar clouds eventually condense into solar nebulae and solar systems, such as ours. The initial water can then be found in comets, planets, and their satellites. In our solar system, water, in liquid or ice form, has been found :
- on the Moon,
- on the planets Mercury, Mars, Neptune, and Pluto,
- on satellites of planets, such as Triton and Europa.

Water on Earth

The water cycle (known scientifically as the hydrologic cycle) refers to the continuous exchange of water within the hydrosphere, between the atmosphere, soil water, surface water, groundwater, and plants. Earth's approximate water volume (the total water supply of the world) is 1,360,000,000 km³ (326,000,000 mi³). Of this volume:
- 1,320,000,000 km³ (316,900,000 mi³ or 97.2%) is in the oceans
- 25,000,000 km³ (6,000,000 mi³ or 1.8%) is in glaciers and icecaps
- 13,000,000 km³ (3,000,000 mi³ or 0.9%) is groundwater.
- 250,000 km³ (60,000 mi³ or 0.02%) is fresh water in lakes, inland seas, and rivers.
- 13,000 km³ (3,100 mi³ or 0.001%) is atmospheric water vapor at any given time. Liquid water is found in bodies of water, such as an ocean, sea, lake, river, stream, canal, or pond. The majority of water on Earth is sea water. Water is also present in the atmosphere in both liquid and vapor phases. It also exists as groundwater in aquifers. Although water normally boils at about 100℃, in deep sea vents the pressurised superheated water reaches a natural temperature of 400℃, whereas at the top of Mount Everest, the low pressure allows water to boil at a mere 70℃.

Water in industry

Water is also used in many industrial processes and machines, such as the steam turbine and heat exchanger, in addition to its use as a chemical solvent. Discharge of untreated water from industrial uses is pollution. Pollution includes discharged solutes (chemical pollution) and discharged coolant water (thermal pollution). Industry requires pure water for many applications and utilizes a variety of purification techniques both in water supply and discharge.

Physics and chemistry of water

Density of water and ice

For most substances, the solid form of the substance is more dense than the liquid form; thus, a block of pure solid substance will sink in a tub of pure liquid substance. But, by contrast, a block of common ice will float in a tub of water because solid water is less dense than liquid water. This is an extremely important characteristic property of water. At room temperature, liquid water becomes denser with lowering temperature, just like other substances. But at 4°C, just above freezing, water reaches its maximum density, and as water cools further toward its freezing point, the liquid water, under standard conditions, expands to become less dense. The physical reason for this is related to the crystal structure of ordinary ice, known as hexagonal ice Ih. Water, gallium, bismuth, acetic acid, antimony and silicon are some of the few materials which expand when they freeze; most other materials contract. It should be noted however, that all forms of ice are not less dense than liquid water. For example HDA and VHDA are both more dense than liquid phase pure water. Thus, the reason that the common form of ice is less dense than water is a bit non-intuitive, and relies heavily on the unusual properties inherent to the hydrogen bond. Generally, water expands when it freezes because of its molecular structure, in tandem with the unusual elasticity of the hydrogen bond and the particular lowest energy hexagonal crystal confirmation that it adopts under standard conditions. That is, when water cools, it tries to stack in a crystalline lattice configuration that stretches the rotational and vibrational components of the bond, so that the effect is that each molecule of water is pushed further from each of its neighboring molecules. This effectively reduces the density ρ of water when ice is formed under standard conditions. The importance of this property cannot be overemphasized for its role on the ecosystem of earth. For example, if water was more dense when frozen, lakes and oceans in a polar environment would eventually freeze solid (from top to bottom). This would happen because frozen ice would settle on the lake and riverbeds, and the necessary warming phenomenon (see below) could not occur in summer, as the warm surface layer would be less dense than the solid frozen layer below. It is a significant feature of nature that this does not occur naturally in the environment, but under synthetic laboratory conditions where HDA and VHDA form, specialized forms of ice are more dense, and do sink to the bottom in liquid water. Nevertheless, the unusual expansion of freezing water (in ordinary natural settings in relevant biological systems), due to the hydrogen bond, from 4 °C above freezing to the freezing point offers an important advantage for freshwater life in winter. Water chilled at the surface becomes denser and sinks, forming convection currents that cool the whole water body, but when the temperature of the lake water reaches 4 °C, water on the surface, as it chills further, becomes less dense, and stays as a surface layer which eventually freezes and forms ice. Since downward convection of colder water is blocked by the density change, any large body of fresh water frozen in winter will have the coldest water near the surface, away from the riverbed or lakebed.

Density of saltwater and ice

The situation in salt water is somewhat different. Ice still floats to keep the oceans from freezing solid (see following paragraph). However, the salt content of oceans both lowers the colligative freezing point by about 2 °C and lowers the temperature of the density maximum of water to be about at the freezing point. Hence, in ocean water, because of the salt content, the downward convection of colder water is not blocked by an expansion of water as it becomes colder near the freezing point; thus the oceans' cold water near the freezing point continues to sink. For this reason, any creature attempting to survive at the bottom of such cold water as the Arctic Ocean generally lives in water that is 4 °C colder than the temperature at the bottom of frozen-over fresh water lakes and rivers in winter. As the surface of salt water begins to freeze (at -1.9 °C for normal salinity seawater, 35‰) the ice that forms is essentially salt free with a density approximately that of freshwater ice. This ice floats on the surface and the salt that is "frozen out" adds to the salinity and density of the seawater just below it. This more dense saltwater sinks by convection and the replacing seawater is subject to the same process. This provides essentially freshwater ice at -1.9 °C on the surface. The increased density of the seawater beneath the forming ice sinks towards the bottom, thus the deep ocean waters should have a minimum temperature of -1.9 °C also.

Triple point

The temperature and pressure at which solid, liquid, and gaseous water coexist in equilibrium is called the triple point of water. This point is used to define the units of temperature (the kelvin and, indirectly, the degree Celsius and even the degree Fahrenheit). The triple point is at a temperature of 273.16 K