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Branched-chain alkanes are called isoparaffins. "Paraffin" is a general term and often does not distinguish between pure compounds and mixtures of isomers, i.e., compounds of the same chemical formula, e.g., pentane and isopentane.
In IUPAC
The following trivial names are retained in the IUPAC system:
isobutane for 2... | Alkane | Wikipedia | 491 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
On the other hand, cycloalkanes tend to have higher boiling points than their linear counterparts due to the locked conformations of the molecules, which give a plane of intermolecular contact.
Melting points
The melting points of the alkanes follow a similar trend to boiling points for the same reason as outlined abo... | Alkane | Wikipedia | 420 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Conductivity and solubility
Alkanes do not conduct electricity in any way, nor are they substantially polarized by an electric field. For this reason, they do not form hydrogen bonds and are insoluble in polar solvents such as water. Since the hydrogen bonds between individual water molecules are aligned away from an a... | Alkane | Wikipedia | 496 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
The spatial arrangement of the bonds is similar to that of the four sp3 orbitals—they are tetrahedrally arranged, with an angle of 109.47° between them. Structural formulae that represent the bonds as being at right angles to one another, while both common and useful, do not accurately depict the geometry.
Conformatio... | Alkane | Wikipedia | 511 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Mass spectrometry
Since alkanes have high ionization energies, their electron impact mass spectra show weak currents for their molecular ions. The fragmentation pattern can be difficult to interpret, but in the case of branched chain alkanes, the carbon chain is preferentially cleaved at tertiary or quaternary carbons ... | Alkane | Wikipedia | 419 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Reactions with oxygen (combustion reaction)
All alkanes react with oxygen in a combustion reaction, although they become increasingly difficult to ignite as the number of carbon atoms increases. The general equation for complete combustion is:
CnH2n+2 + (n + ) O2 → (n + 1) H2O + n CO2
or CnH2n+2 + () O2 → (n + 1) H2O +... | Alkane | Wikipedia | 334 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Free radical reactions
Free radicals, molecules with unpaired electrons, play a large role in most reactions of alkanes. Free radical halogenation reactions occur with halogens, leading to the production of haloalkanes. The hydrogen atoms of the alkane are progressively replaced by halogen atoms. The reaction of alk... | Alkane | Wikipedia | 510 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Isomerization and reformation
Dragan and his colleague were the first to report about isomerization in alkanes. Isomerization and reformation are processes in which straight-chain alkanes are heated in the presence of a platinum catalyst. In isomerization, the alkanes become branched-chain isomers. In other words, it ... | Alkane | Wikipedia | 482 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
The most important commercial sources for alkanes are natural gas and oil. Natural gas contains primarily methane and ethane, with some propane and butane: oil is a mixture of liquid alkanes and other hydrocarbons. These hydrocarbons were formed when marine animals and plants (zooplankton and phytoplankton) died and sa... | Alkane | Wikipedia | 452 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Alkanes play a negligible role in higher organisms, with rare exception.
Some yeasts, e.g., Candida tropicale, Pichia sp., Rhodotorula sp., can use alkanes as a source of carbon or energy. The fungus Amorphotheca resinae prefers the longer-chain alkanes in aviation fuel, and can cause serious problems for aircraft in t... | Alkane | Wikipedia | 416 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Alkanes are found in animal products, although they are less important than unsaturated hydrocarbons. One example is the shark liver oil, which is approximately 14% pristane (2,6,10,14-tetramethylpentadecane, C19H40). They are important as pheromones, chemical messenger materials, on which insects depend for communicat... | Alkane | Wikipedia | 285 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
One example, in which both plant and animal alkanes play a role, is the ecological relationship between the sand bee (Andrena nigroaenea) and the early spider orchid (Ophrys sphegodes); the latter is dependent for pollination on the former. Sand bees use pheromones in order to identify a mate; in the case of A. nigroae... | Alkane | Wikipedia | 468 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Coal
Coal is a more traditional precursor to alkanes. A wide range of technologies have been intensively practiced for centuries. Simply heating coal gives alkanes, leaving behind coke. Relevant technologies include the Bergius process and coal liquifaction. Partial combustion of coal and related solid organic comp... | Alkane | Wikipedia | 207 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Fuels
The dominant use of alkanes is as fuels. Propane and butane, easily liquified gases, are commonly known as liquified petroleum gas (LPG). From pentane to octane the alkanes are highly volatile liquids. They are used as fuels in internal combustion engines, as they vaporize easily on entry into the combustion cha... | Alkane | Wikipedia | 444 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
Alkanes from hexadecane upwards form the most important components of fuel oil and lubricating oil. In the latter function, they work at the same time as anti-corrosive agents, as their hydrophobic nature means that water cannot reach the metal surface. Many solid alkanes find use as paraffin wax, for example, in candl... | Alkane | Wikipedia | 186 | 639 | https://en.wikipedia.org/wiki/Alkane | Physical sciences | Hydrocarbons | null |
An abacus (: abaci or abacuses), also called a counting frame, is a hand-operated calculating tool which was used from ancient times in the ancient Near East, Europe, China, and Russia, until the adoption of the Hindu–Arabic numeral system. An abacus consists of a two-dimensional array of slidable beads (or similar obj... | Abacus | Wikipedia | 465 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
Etymology
The word abacus dates to at least 1387 AD when a Middle English work borrowed the word from Latin that described a sandboard abacus. The Latin word is derived from ancient Greek () which means something without a base, and colloquially, any piece of rectangular material. Alternatively, without reference to ... | Abacus | Wikipedia | 483 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
The earliest archaeological evidence for the use of the Greek abacus dates to the 5th century BC. Demosthenes (384–322 BC) complained that the need to use pebbles for calculations was too difficult. A play by Alexis from the 4th century BC mentions an abacus and pebbles for accounting, and both Diogenes and Polybius us... | Abacus | Wikipedia | 458 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
One example of archaeological evidence of the Roman abacus, shown nearby in reconstruction, dates to the 1st century AD. It has eight long grooves containing up to five beads in each and eight shorter grooves having either one or no beads in each. The groove marked I indicates units, X tens, and so on up to millions. T... | Abacus | Wikipedia | 488 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
In the early Ming dynasty, the abacus began to appear in a 1:5 ratio. The upper deck had one bead and the bottom had five beads. In the late Ming dynasty, the abacus styles appeared in a 2:5 ratio. The upper deck had two beads, and the bottom had five.
Various calculation techniques were devised for Suanpan enabling ... | Abacus | Wikipedia | 423 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
The Abhidharmakośabhāṣya of Vasubandhu (316–396), a Sanskrit work on Buddhist philosophy, says that the second-century CE philosopher Vasumitra said that "placing a wick (Sanskrit vartikā) on the number one (ekāṅka) means it is a one while placing the wick on the number hundred means it is called a hundred, and on the ... | Abacus | Wikipedia | 504 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
The abacus is still manufactured in Japan, despite the proliferation, practicality, and affordability of pocket electronic calculators. The use of the soroban is still taught in Japanese primary schools as part of mathematics, primarily as an aid to faster mental calculation. Using visual imagery, one can complete a ca... | Abacus | Wikipedia | 399 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
The device featured 13 rows with 7 beads, 91 in total. This was a basic number for this culture. It had a close relation to natural phenomena, the underworld, and the cycles of the heavens. One Nepōhualtzintzin (91) represented the number of days that a season of the year lasts, two Nepōhualtzitzin (182) is the number ... | Abacus | Wikipedia | 366 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
The quipu of the Incas was a system of colored knotted cords used to record numerical data, like advanced tally sticks – but not used to perform calculations. Calculations were carried out using a yupana (Quechua for "counting tool"; see figure) which was still in use after the conquest of Peru. The working principle o... | Abacus | Wikipedia | 476 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
The Russian abacus was brought to France around 1820 by mathematician Jean-Victor Poncelet, who had served in Napoleon's army and had been a prisoner of war in Russia. The abacus had fallen out of use in western Europe in the 16th century with the rise of decimal notation and algorismic methods. To Poncelet's French co... | Abacus | Wikipedia | 402 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
Physicist Richard Feynman was noted for facility in mathematical calculations. He wrote about an encounter in Brazil with a Japanese abacus expert, who challenged him to speed contests between Feynman's pen and paper, and the abacus. The abacus was much faster for addition, somewhat faster for multiplication, but Feynm... | Abacus | Wikipedia | 452 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
Although blind students have benefited from talking calculators, the abacus is often taught to these students in early grades. Blind students can also complete mathematical assignments using a braille-writer and Nemeth code (a type of braille code for mathematics) but large multiplication and long division problems are... | Abacus | Wikipedia | 105 | 655 | https://en.wikipedia.org/wiki/Abacus | Technology | Basics_3 | null |
An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid.
The first category of acids are the proton donors, or Brønsted–Lowry acids. In the special case of aqueous solutions, proton... | Acid | Wikipedia | 453 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
The second category of acids are Lewis acids, which form a covalent bond with an electron pair. An example is boron trifluoride (BF3), whose boron atom has a vacant orbital that can form a covalent bond by sharing a lone pair of electrons on an atom in a base, for example the nitrogen atom in ammonia (NH3). Lewis consi... | Acid | Wikipedia | 366 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
In 1884, Svante Arrhenius attributed the properties of acidity to hydrogen ions (H+), later described as protons or hydrons. An Arrhenius acid is a substance that, when added to water, increases the concentration of H+ ions in the water. Chemists often write H+(aq) and refer to the hydrogen ion when describing acid–bas... | Acid | Wikipedia | 487 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Both theories easily describe the first reaction: CH3COOH acts as an Arrhenius acid because it acts as a source of H3O+ when dissolved in water, and it acts as a Brønsted acid by donating a proton to water. In the second example CH3COOH undergoes the same transformation, in this case donating a proton to ammonia (NH3),... | Acid | Wikipedia | 485 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
In the first reaction a fluoride ion, F−, gives up an electron pair to boron trifluoride to form the product tetrafluoroborate. Fluoride "loses" a pair of valence electrons because the electrons shared in the B—F bond are located in the region of space between the two atomic nuclei and are therefore more distant from t... | Acid | Wikipedia | 410 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Acid–base conjugate pairs differ by one proton, and can be interconverted by the addition or removal of a proton (protonation and deprotonation, respectively). The acid can be the charged species and the conjugate base can be neutral in which case the generalized reaction scheme could be written as . In solution there ... | Acid | Wikipedia | 453 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
The strength of an acid refers to its ability or tendency to lose a proton. A strong acid is one that completely dissociates in water; in other words, one mole of a strong acid HA dissolves in water yielding one mole of H+ and one mole of the conjugate base, A−, and none of the protonated acid HA. In contrast, a weak a... | Acid | Wikipedia | 504 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Lewis acid strength in non-aqueous solutions
Lewis acids have been classified in the ECW model and it has been shown that there is no one order of acid strengths. The relative acceptor strength of Lewis acids toward a series of bases, versus other Lewis acids, can be illustrated by C-B plots. It has been shown that t... | Acid | Wikipedia | 449 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
The first dissociation constant is typically greater than the second (i.e., Ka1 > Ka2). For example, sulfuric acid (H2SO4) can donate one proton to form the bisulfate anion (HSO), for which Ka1 is very large; then it can donate a second proton to form the sulfate anion (SO), wherein the Ka2 is intermediate strength. Th... | Acid | Wikipedia | 511 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
where K0 = 1 and the other K-terms are the dissociation constants for the acid.
Neutralization
Neutralization is the reaction between an acid and a base, producing a salt and neutralized base; for example, hydrochloric acid and sodium hydroxide form sodium chloride and water:
HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq)
N... | Acid | Wikipedia | 510 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Equivalence points
Due to the successive dissociation processes, there are two equivalence points in the titration curve of a diprotic acid. The first equivalence point occurs when all first hydrogen ions from the first ionization are titrated. In other words, the amount of OH− added equals the original amount of H2A ... | Acid | Wikipedia | 490 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Acids are often used to remove rust and other corrosion from metals in a process known as pickling. They may be used as an electrolyte in a wet cell battery, such as sulfuric acid in a car battery.
In food
Tartaric acid is an important component of some commonly used foods like unripened mangoes and tamarind. Natural... | Acid | Wikipedia | 484 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Human bodies contain a variety of organic and inorganic compounds, among those dicarboxylic acids play an essential role in many biological behaviors. Many of those acids are amino acids, which mainly serve as materials for the synthesis of proteins. Other weak acids serve as buffers with their conjugate bases to keep ... | Acid | Wikipedia | 273 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
An α-amino acid has a central carbon (the α or alpha carbon) that is covalently bonded to a carboxyl group (thus they are carboxylic acids), an amino group, a hydrogen atom and a variable group. The variable group, also called the R group or side chain, determines the identity and many of the properties of a specific a... | Acid | Wikipedia | 468 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Acid–base equilibrium plays a critical role in regulating mammalian breathing. Oxygen gas (O2) drives cellular respiration, the process by which animals release the chemical potential energy stored in food, producing carbon dioxide (CO2) as a byproduct. Oxygen and carbon dioxide are exchanged in the lungs, and the body... | Acid | Wikipedia | 392 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Mineral acids (inorganic acids)
Hydrogen halides and their solutions: hydrofluoric acid (HF), hydrochloric acid (HCl), hydrobromic acid (HBr), hydroiodic acid (HI)
Halogen oxoacids: hypochlorous acid (HClO), chlorous acid (HClO2), chloric acid (HClO3), perchloric acid (HClO4), and corresponding analogs for bromine an... | Acid | Wikipedia | 393 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Carboxylic acids
A carboxylic acid has the general formula R-C(O)OH, where R is an organic radical. The carboxyl group -C(O)OH contains a carbonyl group, C=O, and a hydroxyl group, O-H.
Acetic acid (CH3COOH)
Citric acid (C6H8O7)
Formic acid (HCOOH)
Gluconic acid HOCH2-(CHOH)4-COOH
Lactic acid (CH3-CHOH-COOH)
Oxal... | Acid | Wikipedia | 294 | 656 | https://en.wikipedia.org/wiki/Acid | Physical sciences | Inorganic compounds | null |
Bitumen ( , ) is an immensely viscous constituent of petroleum. Depending on its exact composition it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American English, the material is commonly referred to as asphalt. Whether found in natural deposits o... | Bitumen | Wikipedia | 491 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
The expression "bitumen" originated in the Sanskrit, where we find the words "jatu", meaning "pitch", and "jatu-krit", meaning "pitch creating", "pitch producing" (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally "gwitu-men" (pertaining to pitch), and by others, "pixt... | Bitumen | Wikipedia | 503 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Modern terminology
Bitumen mixed with clay was usually called "asphaltum", but the term is less commonly used today.
In American English, "asphalt" is equivalent to the British "bitumen". However, "asphalt" is also commonly used as a shortened form of "asphalt concrete" (therefore equivalent to the British "asphalt" ... | Bitumen | Wikipedia | 414 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Normal composition
The components of bitumen include four main classes of compounds:
Naphthene aromatics (naphthalene), consisting of partially hydrogenated polycyclic aromatic compounds
Polar aromatics, consisting of high molecular weight phenols and carboxylic acids produced by partial oxidation of the material
S... | Bitumen | Wikipedia | 470 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Of particular note is the use of re-refined engine oil bottoms – "REOB" or "REOBs"the residue of recycled automotive engine oil collected from the bottoms of re-refining vacuum distillation towers, in the manufacture of asphalt. REOB contains various elements and compounds found in recycled engine oil: additives to the... | Bitumen | Wikipedia | 419 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
The world's largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil. Isotopic studies show the oil deposits to be about 110 milli... | Bitumen | Wikipedia | 458 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
The earliest evidence of bitumen use was discovered when archeologists identified bitumen material on Levallois flint artefacts that date to about 71,000 years BP at the Umm el Tlel open-air site, located on the northern slope of the Qdeir Plateau in el Kowm Basin in Central Syria. Microscopic analyses found bituminous... | Bitumen | Wikipedia | 486 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Bitumen was used by ancient Egyptians to embalm mummies. The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians' primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).
In approximately 40 AD, Dioscorides described the Dead Sea mat... | Bitumen | Wikipedia | 394 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by "a certain Monsieur d'Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel", and that he proposed to use it in a variety of ways – "principally in the... | Bitumen | Wikipedia | 410 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
The first British patent for the use of asphalt was "Cassell's patent asphalte or bitumen" in 1834. Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement, having seen it employed in France and Belgium when visiting with Frederick Walter Simms,... | Bitumen | Wikipedia | 436 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
In 1838, there was a flurry of entrepreneurial activity involving bitumen, which had uses beyond paving. For example, bitumen could also be used for flooring, damp proofing in buildings, and for waterproofing of various types of pools and baths, both of which were also proliferating in the 19th century. One of the earl... | Bitumen | Wikipedia | 395 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
United States
The first use of bitumen in the New World was by aboriginal peoples. On the west coast, as early as the 13th century, the Tongva, Luiseño and Chumash peoples collected the naturally occurring bitumen that seeped to the surface above underlying petroleum deposits. All three groups used the substance as an... | Bitumen | Wikipedia | 378 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
In 1900, Manhattan alone had 130,000 horses, pulling streetcars, wagons, and carriages, and leaving their waste behind. They were not fast, and pedestrians could dodge and scramble their way across the crowded streets. Small towns continued to rely on dirt and gravel, but larger cities wanted much better streets. They ... | Bitumen | Wikipedia | 393 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
The value of the deposit was obvious from the start, but the means of extracting the bitumen was not. The nearest town, Fort McMurray, Alberta, was a small fur trading post, other markets were far away, and transportation costs were too high to ship the raw bituminous sand for paving. In 1915, Sidney Ells of the Federa... | Bitumen | Wikipedia | 410 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Bitumen was the nemesis of many artists during the 19th century. Although widely used for a time, it ultimately proved unstable for use in oil painting, especially when mixed with the most common diluents, such as linseed oil, varnish and turpentine. Unless thoroughly diluted, bitumen never fully solidifies and will in... | Bitumen | Wikipedia | 499 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Rolled asphalt concrete
The largest use of bitumen is for making asphalt concrete for road surfaces; this accounts for approximately 85% of the bitumen consumed in the United States. There are about 4,000 asphalt concrete mixing plants in the US, and a similar number in Europe.
Asphalt concrete pavement mixes are typ... | Bitumen | Wikipedia | 486 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Bitumen emulsions are colloidal mixtures of bitumen and water. Due to the different surface tensions of the two liquids, stable emulsions cannot be created simply by mixing. Therefore, various emulsifiers and stabilizers are added. Emulsifiers are amphiphilic molecules that differ in the charge of their polar head grou... | Bitumen | Wikipedia | 304 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
During the storage of bitumen emulsions, bitumen particles sediment, agglomerate (flocculation), or fuse (coagulation), which leads to a certain instability of the bitumen emulsion. How fast this process occurs depends on the formulation of the bitumen emulsion but also storage conditions such as temperature and humidi... | Bitumen | Wikipedia | 237 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Adhesion problems are reported for anionic emulsions in contact with quartz-rich aggregates. They are substituted by cationic emulsions achieving better adhesion. The extensive range of bitumen emulsions is covered insufficiently by standardization. DIN EN 13808 for cationic asphalt emulsions has been existing since Ju... | Bitumen | Wikipedia | 469 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Bitumen emulsions are used in a wide variety of applications. They are used in road construction and building protection and primarily include the application in cold recycling mixtures, adhesive coating, and surface treatment (1). Due to the lower viscosity in comparison to hot bitumen, processing requires less energy... | Bitumen | Wikipedia | 476 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
In Alberta, five bitumen upgraders produce synthetic crude oil and a variety of other products: The Suncor Energy upgrader near Fort McMurray, Alberta produces synthetic crude oil plus diesel fuel; the Syncrude Canada, Canadian Natural Resources, and Nexen upgraders near Fort McMurray produce synthetic crude oil; and t... | Bitumen | Wikipedia | 483 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Bitumen was used starting in the 1960s as a hydrophobic matrix aiming to encapsulate radioactive waste such as medium-activity salts (mainly soluble sodium nitrate and sodium sulfate) produced by the reprocessing of spent nuclear fuels or radioactive sludges from sedimentation ponds. Bituminised radioactive waste conta... | Bitumen | Wikipedia | 508 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Different types of bitumen have been used: blown bitumen (partly oxidized with air oxygen at high temperature after distillation, and harder) and direct distillation bitumen (softer). Blown bitumens like Mexphalte, with a high content of saturated hydrocarbons, are more easily biodegraded by microorganisms than direct ... | Bitumen | Wikipedia | 438 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Bitumen is typically stored and transported at temperatures around . Sometimes diesel oil or kerosene are mixed in before shipping to retain liquidity; upon delivery, these lighter materials are separated out of the mixture. This mixture is often called "bitumen feedstock", or BFS. Some dump trucks route the hot engine... | Bitumen | Wikipedia | 482 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Albanian deposits
Selenizza is a naturally occurring solid hydrocarbon bitumen found in native deposits in Selenice, in Albania, the only European asphalt mine still in use. The bitumen is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (sol... | Bitumen | Wikipedia | 493 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Recycling
Bitumen is a commonly recycled material in the construction industry. The two most common recycled materials that contain bitumen are reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS). RAP is recycled at a greater rate than any other material in the United States, and typically contains a... | Bitumen | Wikipedia | 511 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
People can be exposed to bitumen in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5mg/m3 over a 15-minute period.
Bitumen is a largely inert material that must be heated or diluted to a point where it be... | Bitumen | Wikipedia | 288 | 657 | https://en.wikipedia.org/wiki/Bitumen | Technology | Building materials | null |
Apollo 11 was a spaceflight conducted from July 16 to July 24, 1969 by the United States and launched by NASA. It marked the first time that humans landed on the Moon. Commander Neil Armstrong and Lunar Module Pilot Buzz Aldrin landed the Apollo Lunar Module Eagle on July 20, 1969, at 20:17 UTC, and Armstrong became th... | Apollo 11 | Wikipedia | 432 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Armstrong's first step onto the lunar surface was broadcast on live TV to a worldwide audience. He described the event as "one small step for [a] man, one giant leap for mankind." Apollo 11 effectively proved U.S. victory in the Space Race to demonstrate spaceflight superiority, by fulfilling a national goal proposed i... | Apollo 11 | Wikipedia | 472 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
In spite of that, the proposed program faced the opposition of many Americans and was dubbed a "moondoggle" by Norbert Wiener, a mathematician at the Massachusetts Institute of Technology. The effort to land a man on the Moon already had a name: Project Apollo. When Kennedy met with Nikita Khrushchev, the Premier of th... | Apollo 11 | Wikipedia | 491 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
The Soviet Union appeared to be winning the Space Race by beating the US to firsts, but its early lead was overtaken by the US Gemini program and Soviet failure to develop the N1 launcher, which would have been comparable to the Saturn V. The Soviets tried to beat the US to return lunar material to the Earth by means ... | Apollo 11 | Wikipedia | 486 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
The Apollo 11 prime crew had none of the close cheerful camaraderie characterized by that of Apollo 12. Instead, they forged an amiable working relationship. Armstrong in particular was notoriously aloof, but Collins, who considered himself a loner, confessed to rebuffing Aldrin's attempts to create a more personal rel... | Apollo 11 | Wikipedia | 456 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
The capsule communicator (CAPCOM) was an astronaut at the Mission Control Center in Houston, Texas, who was the only person who communicated directly with the flight crew. For Apollo 11, the CAPCOMs were: Charles Duke, Ronald Evans, Bruce McCandless II, James Lovell, William Anders, Ken Mattingly, Fred Haise, Don L. Li... | Apollo 11 | Wikipedia | 511 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
The LM was named Eagle after the motif which was featured prominently on the mission insignia. At Scheer's suggestion, the CM was named Columbia after Columbiad, the giant cannon that launched a spacecraft (also from Florida) in Jules Verne's 1865 novel From the Earth to the Moon. It also referred to Columbia, a histor... | Apollo 11 | Wikipedia | 385 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Areas that appeared promising on photographs taken on Earth were often found to be totally unacceptable. The original requirement that the site be free of craters had to be relaxed, as no such site was found. Five sites were considered: Sites 1 and 2 were in the Sea of Tranquility (Mare Tranquillitatis); Site 3 was in ... | Apollo 11 | Wikipedia | 393 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
One of the first versions of the egress checklist had the lunar module pilot exit the spacecraft before the commander, which matched what had been done on Gemini missions, where the commander had never performed the spacewalk. Reporters wrote in early 1969 that Aldrin would be the first man to walk on the Moon, and Ass... | Apollo 11 | Wikipedia | 420 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
The ascent stage of LM-5 Eagle arrived at the Kennedy Space Center on January 8, 1969, followed by the descent stage four days later, and CSM-107 Columbia on January 23. There were several differences between Eagle and Apollo 10's LM-4 Snoopy; Eagle had a VHF radio antenna to facilitate communication with the astronaut... | Apollo 11 | Wikipedia | 356 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Slayton roused the crew shortly after 04:00, and they showered, shaved, and had the traditional pre-flight breakfast of steak and eggs with Slayton and the backup crew. They then donned their space suits and began breathing pure oxygen. At 06:30, they headed out to Launch Complex 39. Haise entered Columbia about three ... | Apollo 11 | Wikipedia | 504 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Apollo 11 entered a near-circular Earth orbit at an altitude of by , twelve minutes into its flight. After one and a half orbits, a second ignition of the S-IVB engine pushed the spacecraft onto its trajectory toward the Moon with the trans-lunar injection (TLI) burn at 16:22:13 UTC. About 30 minutes later, with Colli... | Apollo 11 | Wikipedia | 399 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
As the descent began, Armstrong and Aldrin found themselves passing landmarks on the surface two or three seconds early, and reported that they were "long"; they would land miles west of their target point. Eagle was traveling too fast. The problem could have been mascons—concentrations of high mass in a region or regi... | Apollo 11 | Wikipedia | 417 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
When Armstrong again looked outside, he saw that the computer's landing target was in a boulder-strewn area just north and east of a crater (later determined to be West crater), so he took semi-automatic control. Armstrong considered landing short of the boulder field so they could collect geological samples from it, ... | Apollo 11 | Wikipedia | 483 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Eagle landed at 20:17:40 UTC on Sunday July 20 with of usable fuel remaining. Information available to the crew and mission controllers during the landing showed the LM had enough fuel for another 25 seconds of powered flight before an abort without touchdown would have become unsafe, but post-mission analysis showed ... | Apollo 11 | Wikipedia | 458 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Lunar surface operations
Preparations for Neil Armstrong and Buzz Aldrin to walk on the Moon began at 23:43 UTC. These took longer than expected; three and a half hours instead of two. During training on Earth, everything required had been neatly laid out in advance, but on the Moon the cabin contained a large number ... | Apollo 11 | Wikipedia | 453 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Armstrong intended to say "That's one small step for a man", but the word "a" is not audible in the transmission, and thus was not initially reported by most observers of the live broadcast. When later asked about his quote, Armstrong said he believed he said "for a man", and subsequent printed versions of the quote in... | Apollo 11 | Wikipedia | 357 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Armstrong said moving in the lunar gravity, one-sixth of Earth's, was "even perhaps easier than the simulations ... It's absolutely no trouble to walk around." Aldrin joined him on the surface and tested methods for moving around, including two-footed kangaroo hops. The PLSS backpack created a tendency to tip backward,... | Apollo 11 | Wikipedia | 381 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
They deployed the EASEP, which included a Passive Seismic Experiment Package used to measure moonquakes and a retroreflector array used for the lunar laser ranging experiment. Then Armstrong walked from the LM to take photographs at the rim of Little West Crater while Aldrin collected two core samples. He used the geo... | Apollo 11 | Wikipedia | 435 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Aldrin entered Eagle first. With some difficulty the astronauts lifted film and two sample boxes containing of lunar surface material to the LM hatch using a flat cable pulley device called the Lunar Equipment Conveyor (LEC). This proved to be an inefficient tool, and later missions preferred to carry equipment and sa... | Apollo 11 | Wikipedia | 447 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
After more than hours on the lunar surface, in addition to the scientific instruments, the astronauts left behind: an Apollo 1 mission patch in memory of astronauts Roger Chaffee, Gus Grissom, and Edward White, who died when their command module caught fire during a test in January 1967; two memorial medals of Soviet ... | Apollo 11 | Wikipedia | 484 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
During his day flying solo around the Moon, Collins never felt lonely. Although it has been said "not since Adam has any human known such solitude", Collins felt very much a part of the mission. In his autobiography he wrote: "this venture has been structured for three men, and I consider my third to be as necessary as... | Apollo 11 | Wikipedia | 426 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Eagle rendezvoused with Columbia at 21:24 UTC on July 21, and the two docked at 21:35. Eagles ascent stage was jettisoned into lunar orbit at 23:41. Just before the Apollo 12 flight, it was noted that Eagle was still likely to be orbiting the Moon. Later NASA reports mentioned that Eagle orbit had decayed, resulting in... | Apollo 11 | Wikipedia | 373 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
On July 12, with Apollo 11 still on the launch pad, Hornet departed Pearl Harbor for the recovery area in the central Pacific, in the vicinity of . A presidential party consisting of Nixon, Borman, Secretary of State William P. Rogers and National Security Advisor Henry Kissinger flew to Johnston Atoll on Air Force One... | Apollo 11 | Wikipedia | 453 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Before dawn on July 24, Hornet launched four Sea King helicopters and three Grumman E-1 Tracers. Two of the E-1s were designated as "air boss" while the third acted as a communications relay aircraft. Two of the Sea Kings carried divers and recovery equipment. The third carried photographic equipment, and the fourth ca... | Apollo 11 | Wikipedia | 482 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
After Nixon departed, Hornet was brought alongside the Columbia, which was lifted aboard by the ship's crane, placed on a dolly and moved next to the MQF. It was then attached to the MQF with a flexible tunnel, allowing the lunar samples, film, data tapes and other items to be removed. Hornet returned to Pearl Harbor,... | Apollo 11 | Wikipedia | 511 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
This celebration began a 38-day world tour that brought the astronauts to 22 countries and included visits with many world leaders. The crew toured from September 29 to November 5. The world tour started in Mexico City and ended in Tokyo. Stops on the tour in order were: Mexico City, Bogota, Buenos Aires, Rio de Janeir... | Apollo 11 | Wikipedia | 461 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
Twenty percent of the world's population watched humans walk on the Moon for the first time. While Apollo 11 sparked the interest of the world, the follow-on Apollo missions did not hold the interest of the nation. One possible explanation was the shift in complexity. Landing someone on the Moon was an easy goal to und... | Apollo 11 | Wikipedia | 442 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
The Apollo 11 landing is referenced in the songs "Armstrong, Aldrin and Collins" by the Byrds on the 1969 album Ballad of Easy Rider, "Coon on the Moon" by Howlin' Wolf on the 1973 album The Back Door Wolf, and "One Small Step" by Ayreon on the 2000 album Universal Migrator Part 1: The Dream Sequencer.
Spacecraft
Th... | Apollo 11 | Wikipedia | 476 | 662 | https://en.wikipedia.org/wiki/Apollo%2011 | Technology | Crewed vehicles | null |
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