In fact, in certain Chilean hot springs, opaline silica precipitates out of water in the presence of microorganisms.
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So the vapor precipitates out by clinging to microscopic particles in the air, such as sodium or calcium, and forming crystals.
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In fact, when the calcium ion is removed, the protein precipitates out of solution.
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Antimony potassium tartrate can be prepared by refluxing a solution of potassium hydrogen tartrate and antimony trioxide for 15 minutes. The hot mixture is then filtered and antimony potassium tartrate precipitates out as colourless crystals.
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At this time, uric acid precipitates out, and sodium and potassium ions are actively absorbed by the rectum, along with water via osmosis. Uric acid is left to mix with feces, which are then excreted.
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Molecular laser isotope separation uses an infrared laser directed at UF6, exciting molecules that contain a 235U atom. A second laser frees a fluorine atom, leaving uranium pentafluoride, which then precipitates out of the gas.
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The iron(II) hydroxide reduces these ions to elemental selenium, which is insoluble in water and precipitates out. In a basic solution iron(II) hydroxide is the electrochemically active material of the negative electrode of the nickel-iron battery.
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White cast iron displays white fractured surfaces due to the presence of an iron carbide precipitate called cementite. With a lower silicon content (graphitizing agent) and faster cooling rate, the carbon in white cast iron precipitates out of the melt as the metastable phase cementite, Fe3C, rather than graphite. The cementite which precipitates from the melt forms as relatively large particles. As the iron carbide precipitates out, it withdraws carbon from the original melt, moving the mixture toward one that is closer to eutectic, and the remaining phase is the lower iron-carbon austenite (which on cooling might transform to martensite).
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The oxides are dissolved in nitric acid, but cerium oxide is insoluble in HNO3 and hence precipitates out. Care must be taken when handling some of the residues as they contain 228Ra, the daughter of 232Th, which is a strong gamma emitter.
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When purifying protein from a biological extract, streptomycin sulfate is sometimes added as a means of removing nucleic acids. Since it binds to ribosomes and precipitates out of solution, it serves as a method for removing rRNA, mRNA, and even DNA if the extract is from a prokaryote.
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The acidic filtrates are partially neutralized with sodium hydroxide to pH 3–4. Thorium precipitates out of solution as hydroxide and is removed. After that, the solution is treated with ammonium oxalate to convert rare earths to their insoluble oxalates. The oxalates are converted to oxides by annealing.
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Red copper(I) oxide then precipitates out of the reaction mixture, which indicates a positive result i.e. that redox has taken place (this is the same positive result as with Benedict's solution). Fehling's test can be used as a generic test for monosaccharides and other reducing sugars (e.g., maltose).
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The majority of pipeline maintenance is done by pipeline pigs—mechanical devices sent through the pipeline to perform a variety of functions.Facts, pp. 40–41 The most common pig is the scraper pig,Facts, p. 40 which removes wax that precipitates out of the oil and collects on the walls of the pipeline.
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For example, addition of barium chloride, precipitates out barium sulfate. The filtrate on evaporation yields ammonium chloride. Ammonium sulfate forms many double salts (ammonium metal sulfates) when its solution is mixed with equimolar solutions of metal sulfates and the solution is slowly evaporated. With trivalent metal ions, alums such as ferric ammonium sulfate are formed.
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After separation, it is treated with hot concentrated sulfuric acid to produce water-soluble sulfates of rare earths. The acidic filtrates are partially neutralized with sodium hydroxide to pH 3–4. Thorium precipitates out of solution as hydroxide and is removed. After that, the solution is treated with ammonium oxalate to convert rare earths to their insoluble oxalates.
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Thorium precipitates out of solution as hydroxide and is removed. After that the solution is treated with ammonium oxalate to convert rare earths into their insoluble oxalates. The oxalates are converted to oxides by annealing. The oxides are dissolved in nitric acid that excludes one of the main components, cerium, whose oxide is insoluble in HNO3.
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The anhydrous product is a white, odorless, crystalline solid, hygroscopic and soluble in water (2.5 g/100 g at room temperature). The solutions are basic. Below 50 °C the much less soluble "potassium tetraoxalate" • forms and precipitates out of solution. ChemicalBook (2007) Potassium binoxalate Product Description The monohydrate KHC2O4·H2O starts losing the water at 100 °C.
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Crushed terbium-containing minerals are treated with hot concentrated sulfuric acid to produce water- soluble sulfates of rare earths. The acidic filtrates are partially neutralized with caustic soda to pH 3–4. Thorium precipitates out of solution as hydroxide and is removed. After that the solution is treated with ammonium oxalate to convert rare earths into their insoluble oxalates.
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Thorium precipitates out of solution as hydroxide and is removed. After that, the solution is treated with ammonium oxalate to convert rare earths in to their insoluble oxalates. The oxalates are converted to oxides by annealing. The oxides are dissolved in nitric acid that excludes one of the main components, cerium, whose oxide is insoluble in HNO3.
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Crushed minerals are attacked by hydrochloric or sulfuric acid that transforms insoluble rare-earth oxides into soluble chlorides or sulfates. The acidic filtrates are partially neutralized with caustic soda (sodium hydroxide) to pH 3–4. Thorium precipitates out of solution as hydroxide and is removed. After that the solution is treated with ammonium oxalate to convert rare earths into their insoluble oxalates.
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Biphasic neutralization water treatment is a two-step process. Phase I raises the pH of the outflow to the point that iron precipitates out of solution as ferric hydroxide and arsenic co-precipitates with the ferric hydroxide. This sludge is then removed and disposed of at an appropriate hazardous waste facility. In Phase II the pH of the effluent is raised again and additional metals precipitate.
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In chemistry, recrystallization is a technique used to purify chemicals. By dissolving both impurities and a compound in an appropriate solvent, either the desired compound or impurities can be removed from the solution, leaving the other behind. It is named for the crystals often formed when the compound precipitates out. Alternatively, recrystallization can refer to the natural growth of larger ice crystals at the expense of smaller ones.
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During trituration, mercury diffuses into the silver-tin particles. Then, silver and tin dissolve, to a very limited extent, into the mercury. As this occurs, the particles become smaller. Because the solubility of both silver and tin in mercury is limited and because silver is much less soluble in mercury than is tin, silver precipitates out first as silver-mercury (γ1) followed by tin in the form of tin-mercury (γ2).
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250x250px Some researchers hypothesize that reverse weathering could play a role in the silica cycle at hydrothermal vents. Low temperature hydrothermal vents release silicic acid (DSi) from the Earth's crust, and before it is able to exit the seabed, it cools and precipitates out as clay, such as a smectite. The extent to which reverse weathering at hydrothermal vents adds to the overall silica cycle is a hot topic.
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For example, silver hydroxide Ag(OH) decomposes spontaneously to the oxide (Ag2O). Copper(I) and gold(I) hydroxides are also unstable, although stable adducts of CuOH and AuOH are known. The polymeric compounds M(OH)2 and M(OH)3 are in general prepared by increasing the pH of an aqueous solutions of the corresponding metal cations until the hydroxide precipitates out of solution. On the converse, the hydroxides dissolve in acidic solution.
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This releases the phosphorus back into the water for biological use. The iron and sulfur cycle can interact at several points. Purple sulfur bacteria and green sulfur bacteria can use Fe(II) as an electron donor during anoxic photosynthesis. Sulfate reducing bacteria in anoxic environments can reduce sulfate to sulfide, which then binds to Fe(II) to create iron sulfide, a solid mineral that precipitates out of water and removes the iron and sulfur.
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Molybdenum (Mo), the most common transition metal ion in modern seawater, is also used to look for evidence for euxinia. Weathering of rocks provides an input of MoO42– into oceans. Under oxic conditions, MoO42– is very unreactive, but in modern euxinic environments such as the Black Sea, molybdenum precipitates out as oxythiomolybdate (MoO4−xSx2– ). The isotope ratio for Molybdenum (δ97/95 Mo) in euxinic sediments appears to be higher than in oxic conditions.
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Since the water near the bottom is saturated, the salt precipitates out of solution onto the sea floor. Beginning in the 1960s, water inflow to the Dead Sea from the Jordan River was reduced as a result of large-scale irrigation and generally low rainfall. By 1975, the upper water layer was saltier than the lower layer. Nevertheless, the upper layer remained suspended above the lower layer because its waters were warmer and thus less dense.
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For example, highly linear polyethylene can form platelet-like single crystals with a thickness on the order 10–20 nm when crystallized from a dilute solution. The crystal shape can be more complex for other polymers, including hollow pyramids, spirals and multilayer dendritic structures. A very different process is precipitation; it uses a solvent which dissolves individual monomers but not the resulting polymer. When a certain degree of polymerization is reached, the polymerized and partially crystallized product precipitates out of the solution.
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Schematic of aluminium absorption by human skin. Despite its widespread occurrence in the Earth's crust, aluminium has no known function in biology. At pH 6–9 (relevant for most natural waters), aluminium precipitates out of water as the hydroxide and is hence not available; most elements behaving this way have no biological role or are toxic. Aluminium salts are remarkably nontoxic, aluminium sulfate having an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 435 grams for an person.
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The lower pH caused by the introduction of acid increases the solubility of U(IV), which is typically relatively insoluble and precipitates out of solution at neutral pH. Oxidation states for uranium range from U3+ to U6+, U(III) and U(V) are rarely found, while U(VI) and U(IV) predominate. U(VI) forms stable aqueous complexes and is thus fairly mobile. Preventing the spread of toxic uranium compounds from mining sites often involves reduction of U(VI) to the far less soluble U(IV).
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In the first step in the process, carbon dioxide (CO2) passes through a concentrated aqueous solution of sodium chloride (table salt, NaCl) and ammonia (NH3). : NaCl + CO2 + NH3 + H2O -> NaHCO3 + NH4Cl \---(I) In industrial practice, the reaction is carried out by passing concentrated brine (salt water) through two towers. In the first, ammonia bubbles up through the brine and is absorbed by it. In the second, carbon dioxide bubbles up through the ammoniated brine, and sodium bicarbonate (baking soda) precipitates out of the solution.
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If the aqueous solution is saturated with a given salt solute, any additional such salt precipitates out of the solution. In the more general Brønsted–Lowry acid–base theory (1923), a base is a substance that can accept hydrogen cations (H+)—otherwise known as protons. This does include aqueous hydroxides since OH- does react with H+ to form water, so that Arrhenius bases are a subset of Brønsted bases. However there are also other Brønsted bases which accept protons, such as aqueous solutions of ammonia (NH3) or its organic derivatives (amines).
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Crystal formation can begin by spontaneous nucleation or may be encouraged by the use of a seed. As material precipitates out of the solution, the amount of solute in the flux decreases and the temperature at which the solution is saturated lowers. This process repeats itself as the furnace continues to cool until the solution reaches its melting point or the reaction is stopped artificially. One advantage of this method is that the crystals grown often display natural facets, which often makes preparing crystals for measurement significantly easier.
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Some iron(III) salts, like the chloride , sulfate , and nitrate are soluble in water. However, other salts like oxide (hematite) and iron(III) oxide- hydroxide are extremely insoluble, at least at neutral pH, due to their polymeric structure. Therefore, those soluble iron(III) salts tend to hydrolyze when dissolved in pure water, producing iron(III) hydroxide that immediately converts to polymeric oxide-hydroxide via the process called olation and precipitates out of the solution. That reaction liberates hydrogen ions to the solution, lowering the pH, until an equilibrium is reached.
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Cell membrane details between extracellular and intracellular fluid Sodium-potassium pump and the diffusion between extracellular fluid and intracellular fluid The extracellular fluid provides the medium for the exchange of substances between the ECF and the cells, and this can take place through dissolving, mixing and transporting in the fluid medium. Substances in the ECF include dissolved gases, nutrients, and electrolytes, all needed to maintain life. The ECF also contains materials secreted from cells in soluble form, but which quickly coalesces into fibres (e.g. collagen, reticular, and elastic fibres) or precipitates out into a solid or semisolid form (e.g.
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Analogues have been created that have a shifted isoelectric point so that they exist in a solubility equilibrium in which most precipitates out but slowly dissolves in the bloodstream and is eventually excreted by the kidneys. These insulin analogues are used to replace the basal level of insulin, and may be effective over a period of up to 24 hours. However, some insulin analogues, such as insulin detemir, bind to albumin rather than fat like earlier insulin varieties, and results from long-term usage (e.g. more than 10 years) are currently not available but required for assessment of clinical benefit.
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In water systems subject to heating hardness salts can be deposited as the decomposition of bicarbonate ions creates carbonate ions that precipitate out of solution. Water with high concentrations of hardness salts can be treated with soda ash (sodium carbonate) which precipitates out the excess salts, through the common-ion effect, producing calcium carbonate of very high purity. The precipitated calcium carbonate is traditionally sold to the manufacturers of toothpaste. Several other methods of industrial and residential water treatment are claimed (without general scientific acceptance) to include the use of magnetic and/or electrical fields reducing the effects of hard water.
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Ionium-thorium dating is a technique for determining the age of marine sediments based upon the quantities present of nearly stable thorium-232 and more radioactive thorium-230. (230Th was once known as ionium, before it was realised it was the same element as 232Th.) The radioactive element uranium-238 is soluble in water. However, when it decays into thorium, the latter element is insoluble and so precipitates out to become part of the sediment. Thorium-232 has a halflife of 14.5 billion years, but thorium-230 has a halflife of only 75,200 years, so the ratio is useful for dating sediments up to 400,000 years old.
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Formation of fleur de sel in Feraoun (Algeria) One method of gathering sea salt is to draw seawater into marsh basins or salt pans and allow the water to evaporate, leaving behind the salt that was dissolved in it. As the water evaporates, most of the salt precipitates out on the bottom of the marsh or pan (and is later collected as ordinary sea salt), but some salt crystals float on the surface of the water, forming a delicate crust of intricate pyramidal crystals. This is fleur de sel. The delicacy requires that it be harvested by hand, so this is done with traditional methods using traditional tools.
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When the slightly pressurized calcium bicarbonate hits the air of the cave, the carbon dioxide is released, and the calcium carbonate precipitates out of the water. The calcium carbonate, in the form of the mineral calcite, a solid, crystallizes onto the bottoms and sides of existing stalactites, stalagmites, helictites, and sheets of flowstone to grow the formations over time. Other minerals are brought into the cave by flowing of water to create white, red, tan, and gray colors on the formations and walls. St. Louis Limestone is primarily made of calcite, but is also known to contain magnesium sulfate, manganese dioxide, ferric oxide, gypsum, dolomite, and aragonite.
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The alkali metals dissolve slowly in liquid ammonia, forming ammoniacal solutions of solvated metal cation M+ and solvated electron e−, which react to form hydrogen gas and the alkali metal amide (MNH2, where M represents an alkali metal): this was first noted by Humphry Davy in 1809 and rediscovered by W. Weyl in 1864. The process may be speeded up by a catalyst. Similar solutions are formed by the heavy divalent alkaline earth metals calcium, strontium, barium, as well as the divalent lanthanides, europium and ytterbium. The amide salt is quite insoluble and readily precipitates out of solution, leaving intensely coloured ammonia solutions of the alkali metals.
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The Bunsen reaction is a chemical reaction that describes water, sulfur dioxide, and iodine reacting to form sulfuric acid and hydrogen iodide: : 2H2O + SO2 \+ I2 → H2SO4 \+ 2HI This reaction is the first step in the sulfur- iodine cycle to produce hydrogen. The products separate into two aqueous layers, with the sulfuric acid floating on top, and a mixture of hydrogen iodide and unreacted iodine on the bottom. While the two layers are generally considered immiscible, small amounts of sulfuric acid may still remain in the hydrogen iodide layer and vice versa. This can lead to unwanted side reactions, one of which precipitates out sulfur, a potential obstruction to the reaction vessel.
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This is the case with the conversion of diamond to lower energy graphite at atmospheric pressure, in such a reaction diamond is considered metastable and will not be observed converting into graphite. If the products are higher in chemical energy than the reactants then the reaction will require energy to be performed and is therefore an endergonic reaction. Additionally if the product is less stable than a reactant, then Leffler's assumption holds that the transition state will more closely resemble the product than the reactant. Sometimes the product will differ significantly enough from the reactant that it is easily purified following the reaction such as when a product is insoluble and precipitates out of solution while the reactants remained dissolved.
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In an acidic aqueous solution, thorium occurs as the tetrapositive aqua ion [Th(H2O)9]4+, which has tricapped trigonal prismatic molecular geometry: at pH < 3, the solutions of thorium salts are dominated by this cation. The Th4+ ion is the largest of the tetrapositive actinide ions, and depending on the coordination number can have a radius between 0.95 and 1.14 Å. It is quite acidic due to its high charge, slightly stronger than sulfurous acid: thus it tends to undergo hydrolysis and polymerisation (though to a lesser extent than Fe3+), predominantly to [Th2(OH)2]6+ in solutions with pH 3 or below, but in more alkaline solution polymerisation continues until the gelatinous hydroxide Th(OH)4 forms and precipitates out (though equilibrium may take weeks to be reached, because the polymerisation usually slows down before the precipitation). As a hard Lewis acid, Th4+ favours hard ligands with oxygen atoms as donors: complexes with sulfur atoms as donors are less stable and are more prone to hydrolysis. High coordination numbers are the rule for thorium due to its large size.
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