74-709: [REDACTED] Look up pyro in Wiktionary, the free dictionary. Pyro comes from the Greek word πῦρ (pyr), meaning fire . It may refer to: Businesses [ edit ] Pyro Plastics Corporation , a plastic model kit maker 1940s through the 1970s Pyro Studios , a computer game developer based in Madrid NRK P3 Pyro , a Norwegian Internet-based music radio station Entertainment [ edit ] "Pyro" (song) , by Kings of Leon, 2010 "Pyro",
148-406: A catalyst , a substance that is not consumed, when added, in any chemical reaction during combustion, but which enables the reactants to combust more readily. Once ignited, a chain reaction must take place whereby fires can sustain their own heat by the further release of heat energy in the process of combustion and may propagate, provided there is a continuous supply of an oxidizer and fuel. If
222-403: A high energy fuel for jet and rocket engines , emits intense green flame, leading to its informal nickname of "Green Dragon". The glow of a flame is complex. Black-body radiation is emitted from soot, gas, and fuel particles, though the soot particles are too small to behave like perfect blackbodies. There is also photon emission by de-excited atoms and molecules in the gases. Much of
296-426: A hydride ion . Reductants in chemistry are very diverse. Electropositive elemental metals , such as lithium , sodium , magnesium , iron , zinc , and aluminium , are good reducing agents. These metals donate electrons relatively readily. Hydride transfer reagents , such as NaBH 4 and LiAlH 4 , reduce by atom transfer: they transfer the equivalent of hydride or H . These reagents are widely used in
370-461: A combustible material left after a fire is called clinker if its melting point is below the flame temperature, so that it fuses and then solidifies as it cools, and ash if its melting point is above the flame temperature. Fire is a chemical process in which a fuel and an oxidizing agent react, yielding carbon dioxide and water . This process, known as a combustion reaction , does not proceed directly and involves intermediates . Although
444-489: A controversial gap in the Late Devonian , charcoal is present ever since. The level of atmospheric oxygen is closely related to the prevalence of charcoal: clearly oxygen is the key factor in the abundance of wildfire. Fire also became more abundant when grasses radiated and became the dominant component of many ecosystems, around 6 to 7 million years ago ; this kindling provided tinder which allowed for
518-517: A decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction. There are two classes of redox reactions: "Redox" is a portmanteau of the words "REDuction" and "OXidation." The term "redox" was first used in 1928. Oxidation is a process in which a substance loses electrons. Reduction is a process in which a substance gains electrons. The processes of oxidation and reduction occur simultaneously and cannot occur independently. In redox processes,
592-450: A fire. The most common form of active fire protection is fire sprinklers . To maximize passive fire protection of buildings, building materials and furnishings in most developed countries are tested for fire-resistance , combustibility and flammability . Upholstery , carpeting and plastics used in vehicles and vessels are also tested. Where fire prevention and fire protection have failed to prevent damage, fire insurance can mitigate
666-411: A gas. Later, scientists realized that the metal atom gains electrons in this process. The meaning of reduction then became generalized to include all processes involving a gain of electrons. Reducing equivalent refers to chemical species which transfer the equivalent of one electron in redox reactions. The term is common in biochemistry . A reducing equivalent can be an electron or a hydrogen atom as
740-732: A long history . Fire was the basis of all early thermal weapons . The Byzantine fleet used Greek fire to attack ships and men. The invention of gunpowder in China led to the fire lance , a flame-thrower weapon dating to around 1000 CE which was a precursor to projectile weapons driven by burning gunpowder . The earliest modern flamethrowers were used by infantry in the First World War , first used by German troops against entrenched French troops near Verdun in February 1915. They were later successfully mounted on armoured vehicles in
814-459: A more easily corroded " sacrificial anode " to act as the anode . The sacrificial metal, instead of the protected metal, then corrodes. A common application of cathodic protection is in galvanized steel, in which a sacrificial zinc coating on steel parts protects them from rust. Oxidation is used in a wide variety of industries, such as in the production of cleaning products and oxidizing ammonia to produce nitric acid . Redox reactions are
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#1732786951177888-472: A person afflicted with pyromania , the inability to resist the impulse to deliberately start fires Pyro cable, mineral-insulated copper-clad cable (MICC), a fire-resistant electrical cable Probabilistic programming language Pyro, extending from PyTorch See also [ edit ] Pyrrho of Elis (360–270 BC), Greek philosopher, founder of Pyrrhonism Pyros (disambiguation) All pages with titles containing Pyro Topics referred to by
962-413: A redox reaction that takes place in a cell, the potential difference is: However, the potential of the reaction at the anode is sometimes expressed as an oxidation potential : The oxidation potential is a measure of the tendency of the reducing agent to be oxidized but does not represent the physical potential at an electrode. With this notation, the cell voltage equation is written with a plus sign In
1036-631: A series of mechanisms that behave differently in micro gravity when compared to normal gravity conditions. These discoveries have potential applications in applied science and industry , especially concerning fuel efficiency . The adiabatic flame temperature of a given fuel and oxidizer pair is that at which the gases achieve stable combustion. Fire science is a branch of physical science which includes fire behavior, dynamics, and combustion . Applications of fire science include fire protection , fire investigation , and wildfire management. Every natural ecosystem on land has its own fire regime , and
1110-436: A similar point in time. The use of fire became progressively more sophisticated, as it was used to create charcoal and to control wildlife from tens of thousands of years ago. Fire has also been used for centuries as a method of torture and execution, as evidenced by death by burning as well as torture devices such as the iron boot , which could be filled with water, oil , or even lead and then heated over an open fire to
1184-725: A song by Denzel Curry and Kenny Beats from their 2020 EP Unlocked Pyro (Marvel Comics) , a Marvel Comics supervillain Pyro ( Team Fortress 2 ) , one of the playable classes in the video game Pyro... The Thing Without a Face , a 1964 film starring Barry Sullivan and Martha Hyer A god in the video game Sacrifice One of the seven elements in the video game Genshin Impact Other uses [ edit ] Pyro (horse) , an American thoroughbred racehorse Pyro, Ohio , United States USS Pyro , two U.S. Navy ammunition ships Short for pyrotechnics Slang for
1258-560: A song by T.S.O.L. from their 2001 album Disappear "Pyro", a song by Hail the Villain from their 2010 album Population: Declining "Pyro", a song by the Standstills from their 2012 album Pushing Electric "Pyro", a song by 2:54 from their 2014 album The Other I "Pyro", a song by Shinedown from their 2018 album Attention Attention "Pyro", a song by Budjerah from his 2021 self-titled EP "Pyro (leak 2019)",
1332-405: Is a significant process that influences ecological systems worldwide. The positive effects of fire include stimulating growth and maintaining various ecological systems. Its negative effects include hazard to life and property, atmospheric pollution, and water contamination. When fire removes protective vegetation , heavy rainfall can contribute to increased soil erosion by water . Additionally,
1406-447: Is also known as its reduction potential ( E red ), or potential when the half-reaction takes place at a cathode. The reduction potential is a measure of the tendency of the oxidizing agent to be reduced. Its value is zero for H + e → 1 ⁄ 2 H 2 by definition, positive for oxidizing agents stronger than H (e.g., +2.866 V for F 2 ) and negative for oxidizing agents that are weaker than H (e.g., −0.763V for Zn ). For
1480-469: Is dependent on these ratios. Redox mechanisms also control some cellular processes. Redox proteins and their genes must be co-located for redox regulation according to the CoRR hypothesis for the function of DNA in mitochondria and chloroplasts . Wide varieties of aromatic compounds are enzymatically reduced to form free radicals that contain one more electron than their parent compounds. In general,
1554-397: Is different from Wikidata All article disambiguation pages All disambiguation pages Fire Fire is the rapid oxidation of a material (the fuel ) in the exothermic chemical process of combustion , releasing heat , light , and various reaction products . At a certain point in the combustion reaction, called the ignition point, flames are produced. The flame
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#17327869511771628-537: Is feeding the fire. Fire prevention is intended to reduce sources of ignition. Fire prevention also includes education to teach people how to avoid causing fires. Buildings, especially schools and tall buildings, often conduct fire drills to inform and prepare citizens on how to react to a building fire. Purposely starting destructive fires constitutes arson and is a crime in most jurisdictions. Model building codes require passive fire protection and active fire protection systems to minimize damage resulting from
1702-417: Is its use to clear land for agriculture. Slash-and-burn agriculture is still common across much of tropical Africa, Asia and South America. For small farmers, controlled fires are a convenient way to clear overgrown areas and release nutrients from standing vegetation back into the soil. However, this useful strategy is also problematic. Growing population, fragmentation of forests and warming climate are making
1776-432: Is mined as its magnetite (Fe 3 O 4 ). Titanium is mined as its dioxide, usually in the form of rutile (TiO 2 ). These oxides must be reduced to obtain the corresponding metals, often achieved by heating these oxides with carbon or carbon monoxide as reducing agents. Blast furnaces are the reactors where iron oxides and coke (a form of carbon) are combined to produce molten iron. The main chemical reaction producing
1850-505: Is not the reverse of the redox reaction in cellular respiration: Biological energy is frequently stored and released using redox reactions. Photosynthesis involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen. The reverse reaction, respiration, oxidizes sugars to produce carbon dioxide and water. As intermediate steps, the reduced carbon compounds are used to reduce nicotinamide adenine dinucleotide (NAD ) to NADH, which then contributes to
1924-404: Is one of the four classical elements and has been used by humans in rituals , in agriculture for clearing land, for cooking, generating heat and light, for signaling, propulsion purposes, smelting , forging , incineration of waste, cremation , and as a weapon or mode of destruction. The word "fire" originated from Old English Fyr 'Fire, a fire', which can be traced back to
1998-479: Is the visible portion of the fire. Flames consist primarily of carbon dioxide, water vapor, oxygen and nitrogen. If hot enough, the gases may become ionized to produce plasma . Depending on the substances alight, and any impurities outside, the color of the flame and the fire's intensity will be different. Fire, in its most common form, has the potential to result in conflagration , which can lead to physical damage, which can be permanent, through burning . Fire
2072-417: Is used by nearly every human being on Earth in a controlled setting every day. Users of internal combustion vehicles employ fire every time they drive. Thermal power stations provide electricity for a large percentage of humanity by igniting fuels such as coal , oil or natural gas , then using the resultant heat to boil water into steam , which then drives turbines . The use of fire in warfare has
2146-602: The Germanic root * fūr- , which itself comes from the Proto-Indo-European * perjos from the root * paewr- ' fire ' . The current spelling of "fire" has been in use since as early as 1200, but it was not until around 1600 that it completely replaced the Middle English term fier (which is still preserved in the word "fiery"). The fossil record of fire first appears with
2220-408: The flash point for the fuel /oxidizer mix, and is able to sustain a rate of rapid oxidation that produces a chain reaction . This is commonly called the fire tetrahedron . Fire cannot exist without all of these elements in place and in the right proportions. For example, a flammable liquid will start burning only if the fuel and oxygen are in the right proportions. Some fuel-oxygen mixes may require
2294-575: The Second World War, notably on Coventry , Tokyo , Rotterdam , London , Hamburg and Dresden ; in the latter two cases firestorms were deliberately caused in which a ring of fire surrounding each city was drawn inward by an updraft caused by a central cluster of fires. The United States Army Air Force also extensively used incendiaries against Japanese targets in the latter months of the war, devastating entire cities constructed primarily of wood and paper houses. The incendiary fluid napalm
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2368-504: The Second World War. Hand-thrown incendiary bombs improvised from glass bottles, later known as Molotov cocktails , were deployed during the Spanish Civil War in the 1930s. Also during that war, incendiary bombs were deployed against Guernica by Fascist Italian and Nazi German air forces that had been created specifically to support Franco's Nationalists . Incendiary bombs were dropped by Axis and Allies during
2442-476: The agony of the wearer. By the Neolithic Revolution , during the introduction of grain-based agriculture, people all over the world used fire as a tool in landscape management. These fires were typically controlled burns or "cool fires", as opposed to uncontrolled "hot fires", which damage the soil. Hot fires destroy plants and animals, and endanger communities. This is especially a problem in
2516-491: The burning of vegetation releases nitrogen into the atmosphere, unlike elements such as potassium and phosphorus which remain in the ash and are quickly recycled into the soil. This loss of nitrogen caused by a fire produces a long-term reduction in the fertility of the soil, which can be recovered as atmospheric nitrogen is fixed and converted to ammonia by natural phenomena such as lightning or by leguminous plants such as clover , peas , and green beans . Fire
2590-443: The copper sulfate solution, thus liberating free copper metal. The reaction is spontaneous and releases 213 kJ per 65 g of zinc. The ionic equation for this reaction is: As two half-reactions , it is seen that the zinc is oxidized: And the copper is reduced: A disproportionation reaction is one in which a single substance is both oxidized and reduced. For example, thiosulfate ion with sulfur in oxidation state +2 can react in
2664-479: The creation of a proton gradient , which drives the synthesis of adenosine triphosphate (ATP) and is maintained by the reduction of oxygen. In animal cells, mitochondria perform similar functions. Free radical reactions are redox reactions that occur as part of homeostasis and killing microorganisms . In these reactions, an electron detaches from a molecule and then re-attaches almost instantly. Free radicals are part of redox molecules and can become harmful to
2738-540: The earth's surface more prone to ever-larger escaped fires. These harm ecosystems and human infrastructure, cause health problems, and send up spirals of carbon and soot that may encourage even more warming of the atmosphere – and thus feed back into more fires. Globally today, as much as 5 million square kilometres – an area more than half the size of the United States – burns in a given year. There are numerous modern applications of fire. In its broadest sense, fire
2812-476: The electron donor is any of a wide variety of flavoenzymes and their coenzymes . Once formed, these anion free radicals reduce molecular oxygen to superoxide and regenerate the unchanged parent compound. The net reaction is the oxidation of the flavoenzyme's coenzymes and the reduction of molecular oxygen to form superoxide. This catalytic behavior has been described as a futile cycle or redox cycling. Minerals are generally oxidized derivatives of metals. Iron
2886-415: The electrons cancel: The protons and fluoride combine to form hydrogen fluoride in a non-redox reaction: The overall reaction is: In this type of reaction, a metal atom in a compound or solution is replaced by an atom of another metal. For example, copper is deposited when zinc metal is placed in a copper(II) sulfate solution: In the above reaction, zinc metal displaces the copper(II) ion from
2960-446: The environment. Cellular respiration , for instance, is the oxidation of glucose (C 6 H 12 O 6 ) to CO 2 and the reduction of oxygen to water . The summary equation for cellular respiration is: The process of cellular respiration also depends heavily on the reduction of NAD to NADH and the reverse reaction (the oxidation of NADH to NAD ). Photosynthesis and cellular respiration are complementary, but photosynthesis
3034-611: The establishment of a land-based flora in the Middle Ordovician period, 470 million years ago , permitting the accumulation of oxygen in the atmosphere as never before, as the new hordes of land plants pumped it out as a waste product. When this concentration rose above 13%, it permitted the possibility of wildfire . Wildfire is first recorded in the Late Silurian fossil record, 420 million years ago , by fossils of charcoalified plants. Apart from
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3108-652: The familiar red-orange glow of "fire". This light has a continuous spectrum . Complete combustion of gas has a dim blue color due to the emission of single-wavelength radiation from various electron transitions in the excited molecules formed in the flame. Usually oxygen is involved, but hydrogen burning in chlorine also produces a flame, producing hydrogen chloride (HCl). Other possible combinations producing flames, amongst many, are fluorine and hydrogen , and hydrazine and nitrogen tetroxide . Hydrogen and hydrazine/ UDMH flames are similarly pale blue, while burning boron and its compounds, evaluated in mid-20th century as
3182-410: The financial impact. Oxidation Redox ( / ˈ r ɛ d ɒ k s / RED -oks , / ˈ r iː d ɒ k s / REE -doks , reduction–oxidation or oxidation–reduction ) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or
3256-407: The fire. Because of this, the risk of fire in a spacecraft is small when it is coasting in inertial flight. This does not apply if oxygen is supplied to the fire by some process other than thermal convection. Fire can be extinguished by removing any one of the elements of the fire tetrahedron. Consider a natural gas flame, such as from a stove-top burner. The fire can be extinguished by any of
3330-668: The flame becomes spherical, with a tendency to become more blue and more efficient (although it may go out if not moved steadily, as the CO 2 from combustion does not disperse as readily in microgravity, and tends to smother the flame). There are several possible explanations for this difference, of which the most likely is that the temperature is sufficiently evenly distributed that soot is not formed and complete combustion occurs. Experiments by NASA reveal that diffusion flames in microgravity allow more soot to be completely oxidized after they are produced than diffusion flames on Earth, because of
3404-405: The following: In contrast, fire is intensified by increasing the overall rate of combustion. Methods to do this include balancing the input of fuel and oxidizer to stoichiometric proportions, increasing fuel and oxidizer input in this balanced mix, increasing the ambient temperature so the fire's own heat is better able to sustain combustion, or providing a catalyst, a non-reactant medium in which
3478-595: The food. The heat produced would also help people stay warm in cold weather, enabling them to live in cooler climates. Fire also kept nocturnal predators at bay. Evidence of occasional cooked food is found from 1 million years ago . Although this evidence shows that fire may have been used in a controlled fashion about 1 million years ago, other sources put the date of regular use at 400,000 years ago. Evidence becomes widespread around 50 to 100 thousand years ago, suggesting regular use from this time; resistance to air pollution started to evolve in human populations at
3552-484: The forests of today where traditional burning is prevented in order to encourage the growth of timber crops. Cool fires are generally conducted in the spring and autumn. They clear undergrowth, burning up biomass that could trigger a hot fire should it get too dense. They provide a greater variety of environments, which encourages game and plant diversity. For humans, they make dense, impassable forests traversable. Another human use for fire in regards to landscape management
3626-660: The foundation of electrochemical cells, which can generate electrical energy or support electrosynthesis . Metal ores often contain metals in oxidized states, such as oxides or sulfides, from which the pure metals are extracted by smelting at high temperatures in the presence of a reducing agent. The process of electroplating uses redox reactions to coat objects with a thin layer of a material, as in chrome-plated automotive parts, silver plating cutlery , galvanization and gold-plated jewelry . Many essential biological processes involve redox reactions. Before some of these processes can begin, iron must be assimilated from
3700-460: The fuel and oxidizer can more readily react. A flame is a mixture of reacting gases and solids emitting visible, infrared , and sometimes ultraviolet light, the frequency spectrum of which depends on the chemical composition of the burning material and intermediate reaction products. In many cases, such as the burning of organic matter , for example wood, or the incomplete combustion of gas, incandescent solid particles called soot produce
3774-646: The fuel; how to stoke the fire both in early phases and in maintenance phases; how to modulate the heat, flame, and smoke as suited to the desired application; how best to bank a fire to be revived later; how to choose, design, or modify stoves, fireplaces, bakery ovens, or industrial furnaces ; and so on. Detailed expositions of fire management are available in various books about blacksmithing, about skilled camping or military scouting , and about domestic arts . Burning fuel converts chemical energy into heat energy; wood has been used as fuel since prehistory . The International Energy Agency states that nearly 80% of
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#17327869511773848-413: The human body if they do not reattach to the redox molecule or an antioxidant . The term redox state is often used to describe the balance of GSH/GSSG , NAD /NADH and NADP /NADPH in a biological system such as a cell or organ . The redox state is reflected in the balance of several sets of metabolites (e.g., lactate and pyruvate , beta-hydroxybutyrate and acetoacetate ), whose interconversion
3922-456: The meaning was generalized to include all processes involving the loss of electrons or the increase in the oxidation state of a chemical species. Substances that have the ability to oxidize other substances (cause them to lose electrons) are said to be oxidative or oxidizing, and are known as oxidizing agents , oxidants, or oxidizers. The oxidant removes electrons from another substance, and is thus itself reduced. Because it "accepts" electrons,
3996-492: The molten iron is: Electron transfer reactions are central to myriad processes and properties in soils, and redox potential , quantified as Eh (platinum electrode potential ( voltage ) relative to the standard hydrogen electrode) or pe (analogous to pH as -log electron activity), is a master variable, along with pH, that controls and is governed by chemical reactions and biological processes. Early theoretical research with applications to flooded soils and paddy rice production
4070-473: The more rapid spread of fire. These widespread fires may have initiated a positive feedback process, whereby they produced a warmer, drier climate more conducive to fire. The ability to control fire was a dramatic change in the habits of early humans. Making fire to generate heat and light made it possible for people to cook food, simultaneously increasing the variety and availability of nutrients and reducing disease by killing pathogenic microorganisms in
4144-435: The organisms in those ecosystems are adapted to or dependent upon that fire regime. Fire creates a mosaic of different habitat patches, each at a different stage of succession . Different species of plants, animals, and microbes specialize in exploiting a particular stage, and by creating these different types of patches, fire allows a greater number of species to exist within a landscape. Wildfire prevention programs around
4218-407: The oxidizer is oxygen from the surrounding air, the presence of a force of gravity , or of some similar force caused by acceleration, is necessary to produce convection , which removes combustion products and brings a supply of oxygen to the fire. Without gravity, a fire rapidly surrounds itself with its own combustion products and non-oxidizing gases from the air, which exclude oxygen and extinguish
4292-449: The oxidizing agent is also called an electron acceptor . Oxidants are usually chemical substances with elements in high oxidation states (e.g., N 2 O 4 , MnO 4 , CrO 3 , Cr 2 O 7 , OsO 4 ), or else highly electronegative elements (e.g. O 2 , F 2 , Cl 2 , Br 2 , I 2 ) that can gain extra electrons by oxidizing another substance. Oxidizers are oxidants, but
4366-421: The oxidizing agent is typically oxygen , other compounds are able to fulfill the role. For instance, chlorine trifluoride is able to ignite sand . Fires start when a flammable or a combustible material, in combination with a sufficient quantity of an oxidizer such as oxygen gas or another oxygen-rich compound (though non-oxygen oxidizers exist), is exposed to a source of heat or ambient temperature above
4440-404: The presence of acid to form elemental sulfur (oxidation state 0) and sulfur dioxide (oxidation state +4). Thus one sulfur atom is reduced from +2 to 0, while the other is oxidized from +2 to +4. Cathodic protection is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell . A simple method of protection connects protected metal to
4514-495: The radiation is emitted in the visible and infrared bands. The color depends on temperature for the black-body radiation, and on chemical makeup for the emission spectra . The common distribution of a flame under normal gravity conditions depends on convection , as soot tends to rise to the top of a general flame, as in a candle in normal gravity conditions, making it yellow. In microgravity or zero gravity , such as an environment in outer space , convection no longer occurs, and
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#17327869511774588-544: The reaction between hydrogen and fluorine , hydrogen is being oxidized and fluorine is being reduced: This spontaneous reaction releases 542 kJ per 2 g of hydrogen because the H-F bond is much stronger than the F-F bond. This reaction can be analyzed as two half-reactions . The oxidation reaction converts hydrogen to protons : The reduction reaction converts fluorine to the fluoride anion: The half-reactions are combined so that
4662-410: The reducing agent is also called an electron donor . Electron donors can also form charge transfer complexes with electron acceptors. The word reduction originally referred to the loss in weight upon heating a metallic ore such as a metal oxide to extract the metal. In other words, ore was "reduced" to metal. Antoine Lavoisier demonstrated that this loss of weight was due to the loss of oxygen as
4736-455: The reductant transfers electrons to the oxidant. Thus, in the reaction, the reductant or reducing agent loses electrons and is oxidized, and the oxidant or oxidizing agent gains electrons and is reduced. The pair of an oxidizing and reducing agent that is involved in a particular reaction is called a redox pair. A redox couple is a reducing species and its corresponding oxidizing form, e.g., Fe / Fe .The oxidation alone and
4810-458: The reduction alone are each called a half-reaction because two half-reactions always occur together to form a whole reaction. In electrochemical reactions the oxidation and reduction processes do occur simultaneously but are separated in space. Oxidation originally implied a reaction with oxygen to form an oxide. Later, the term was expanded to encompass substances that accomplished chemical reactions similar to those of oxygen. Ultimately,
4884-494: The reduction of carbonyl compounds to alcohols . A related method of reduction involves the use of hydrogen gas (H 2 ) as sources of H atoms. The electrochemist John Bockris proposed the words electronation and de-electronation to describe reduction and oxidation processes, respectively, when they occur at electrodes . These words are analogous to protonation and deprotonation . They have not been widely adopted by chemists worldwide, although IUPAC has recognized
4958-405: The same term [REDACTED] This disambiguation page lists articles associated with the title Pyro . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Pyro&oldid=1259853752 " Category : Disambiguation pages Hidden categories: Short description
5032-437: The term is mainly reserved for sources of oxygen, particularly in the context of explosions. Nitric acid is a strong oxidizer. Substances that have the ability to reduce other substances (cause them to gain electrons) are said to be reductive or reducing and are known as reducing agents , reductants, or reducers. The reductant transfers electrons to another substance and is thus itself oxidized. Because it donates electrons,
5106-658: The terms electronation and de-electronation. Redox reactions can occur slowly, as in the formation of rust , or rapidly, as in the case of burning fuel . Electron transfer reactions are generally fast, occurring within the time of mixing. The mechanisms of atom-transfer reactions are highly variable because many kinds of atoms can be transferred. Such reactions can also be quite complex, involving many steps. The mechanisms of electron-transfer reactions occur by two distinct pathways, inner sphere electron transfer and outer sphere electron transfer . Analysis of bond energies and ionization energies in water allows calculation of
5180-446: The thermodynamic aspects of redox reactions. Each half-reaction has a standard electrode potential ( E cell ), which is equal to the potential difference or voltage at equilibrium under standard conditions of an electrochemical cell in which the cathode reaction is the half-reaction considered, and the anode is a standard hydrogen electrode where hydrogen is oxidized: The electrode potential of each half-reaction
5254-573: The world may employ techniques such as wildland fire use and prescribed or controlled burns . Wildland fire use refers to any fire of natural causes that is monitored but allowed to burn. Controlled burns are fires ignited by government agencies under less dangerous weather conditions. Fire fighting services are provided in most developed areas to extinguish or contain uncontrolled fires. Trained firefighters use fire apparatus , water supply resources such as water mains and fire hydrants or they might use A and B class foam depending on what
5328-462: The world's power has consistently come from fossil fuels such as petroleum , natural gas , and coal in the past decades. The fire in a power station is used to heat water, creating steam that drives turbines . The turbines then spin an electric generator to produce electricity. Fire is also used to provide mechanical work directly by thermal expansion , in both external and internal combustion engines . The unburnable solid remains of
5402-433: Was seminal for subsequent work on thermodynamic aspects of redox and plant root growth in soils. Later work built on this foundation, and expanded it for understanding redox reactions related to heavy metal oxidation state changes, pedogenesis and morphology, organic compound degradation and formation, free radical chemistry, wetland delineation, soil remediation , and various methodological approaches for characterizing
5476-655: Was used in July 1944, towards the end of the Second World War , although its use did not gain public attention until the Vietnam War . Controlling a fire to optimize its size, shape, and intensity is generally called fire management , and the more advanced forms of it, as traditionally (and sometimes still) practiced by skilled cooks, blacksmiths , ironmasters , and others, are highly skilled activities. They include knowledge of which fuel to burn; how to arrange
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