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72-529: The RERF was created in 1956 to act as a store of wealth for the country's earnings from phosphate mining, which at one time accounted for 50% of government revenue. In 2009 the RERF was valued at A$ 570.5 million. The RERF assets declined from A$ 637 million (420 percent of GDP) in 2007 to A$ 570.5 million (350 percent of GDP) in 2009. As the result of the Global Financial Crisis (GFC) the RERF

144-538: A differ by more than 4. Phosphate can form many polymeric ions such as pyrophosphate , (P 2 O 7 ) , and triphosphate , (P 3 O 10 ) . The various metaphosphate ions (which are usually long linear polymers) have an empirical formula of (PO 3 ) and are found in many compounds. In biological systems , phosphorus can be found as free phosphate anions in solution ( inorganic phosphate ) or bound to organic molecules as various organophosphates . Inorganic phosphate

216-675: A molar mass of 94.97 g/mol, and consists of a central phosphorus atom surrounded by four oxygen atoms in a tetrahedral arrangement. It is the conjugate base of the hydrogen phosphate ion H(PO 4 ) , which in turn is the conjugate base of the dihydrogen phosphate ion H 2 (PO 4 ) , which in turn is the conjugate base of orthophosphoric acid , H 3 PO 4 . Many phosphates are soluble in water at standard temperature and pressure . The sodium, potassium, rubidium , caesium , and ammonium phosphates are all water-soluble. Most other phosphates are only slightly soluble or are insoluble in water. As

288-471: A " peak phosphorus " would occur in 30 years and Dana Cordell from Institute for Sustainable Futures said that at "current rates, reserves will be depleted in the next 50 to 100 years". Reserves refer to the amount assumed recoverable at current market prices. In 2012 the USGS estimated world reserves at 71 billion tons, while 0.19 billion tons were mined globally in 2011. Phosphorus comprises 0.1% by mass of

360-421: A given compound may increase or decrease with temperature. The van 't Hoff equation relates the change of solubility equilibrium constant ( K sp ) to temperature change and to reaction enthalpy change. For most solids and liquids, their solubility increases with temperature because their dissolution reaction is endothermic (Δ H  > 0). In liquid water at high temperatures, (e.g. that approaching

432-473: A high phosphate-to-protein ratio, such as soft drinks, fast food, processed foods, condiments, and other products containing phosphate-salt additives is advised. Phosphates induce vascular calcification , and a high concentration of phosphates in blood was found to be a predictor of cardiovascular events . Phosphates are the naturally occurring form of the element phosphorus , found in many phosphate minerals . In mineralogy and geology, phosphate refers to

504-447: A large increase in solubility with temperature (Δ H  > 0). Some solutes (e.g. sodium chloride in water) exhibit solubility that is fairly independent of temperature (Δ H  ≈ 0). A few, such as calcium sulfate ( gypsum ) and cerium(III) sulfate , become less soluble in water as temperature increases (Δ H  < 0). This is also the case for calcium hydroxide ( portlandite ), whose solubility at 70 °C

576-422: A lesser extent, solubility will depend on the ionic strength of solutions. The last two effects can be quantified using the equation for solubility equilibrium . For a solid that dissolves in a redox reaction, solubility is expected to depend on the potential (within the range of potentials under which the solid remains the thermodynamically stable phase). For example, solubility of gold in high-temperature water

648-505: A long time to establish (hours, days, months, or many years; depending on the nature of the solute and other factors). The rate of dissolution can be often expressed by the Noyes–Whitney equation or the Nernst and Brunner equation of the form: where: For dissolution limited by diffusion (or mass transfer if mixing is present), C s {\displaystyle C_{s}}

720-411: A minimum, which is below 120 °C for most permanent gases ), but more soluble in organic solvents (endothermic dissolution reaction related to their solvation). The chart shows solubility curves for some typical solid inorganic salts in liquid water (temperature is in degrees Celsius , i.e. kelvins minus 273.15). Many salts behave like barium nitrate and disodium hydrogen arsenate , and show

792-850: A molecular form that algae can break down and consume. Calcium hydroxyapatite and calcite precipitates can be found around bacteria in alluvial topsoil. As clay minerals promote biomineralization, the presence of bacteria and clay minerals resulted in calcium hydroxyapatite and calcite precipitates. Phosphate deposits can contain significant amounts of naturally occurring heavy metals. Mining operations processing phosphate rock can leave tailings piles containing elevated levels of cadmium , lead , nickel , copper , chromium , and uranium . Unless carefully managed, these waste products can leach heavy metals into groundwater or nearby estuaries. Uptake of these substances by plants and marine life can lead to concentration of toxic heavy metals in food products. Solubility In chemistry , solubility

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864-521: A more complex pattern is observed, as with sodium sulfate , where the less soluble deca hydrate crystal ( mirabilite ) loses water of crystallization at 32 °C to form a more soluble anhydrous phase ( thenardite ) with a smaller change in Gibbs free energy (Δ G ) in the dissolution reaction. The solubility of organic compounds nearly always increases with temperature. The technique of recrystallization , used for purification of solids, depends on

936-426: A percentage in this case, and the abbreviation "w/w" may be used to indicate "weight per weight". (The values in g/L and g/kg are similar for water, but that may not be the case for other solvents.) Alternatively, the solubility of a solute can be expressed in moles instead of mass. For example, if the quantity of solvent is given in kilograms , the value is the molality of the solution (mol/kg). The solubility of

1008-406: A percentage, and the abbreviation "v/v" for "volume per volume" may be used to indicate this choice. Conversion between these various ways of measuring solubility may not be trivial, since it may require knowing the density of the solution — which is often not measured, and cannot be predicted. While the total mass is conserved by dissolution, the final volume may be different from both the volume of

1080-829: A rock or ore containing phosphate ions. Inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry. The largest global producer and exporter of phosphates is Morocco . Within North America, the largest deposits lie in the Bone Valley region of central Florida , the Soda Springs region of southeastern Idaho , and the coast of North Carolina . Smaller deposits are located in Montana , Tennessee , Georgia , and South Carolina . The small island nation of Nauru and its neighbor Banaba Island , which used to have massive phosphate deposits of

1152-450: A rule, the hydrogen and dihydrogen phosphates are slightly more soluble than the corresponding phosphates. In water solution, orthophosphoric acid and its three derived anions coexist according to the dissociation and recombination equilibria below Values are at 25   °C and 0 ionic strength. The p K a values are the pH values where the concentration of each species is equal to that of its conjugate bases . At pH 1 or lower,

1224-471: A simple ionic compound (with positive and negative ions) such as sodium chloride (common salt) is easily soluble in a highly polar solvent (with some separation of positive (δ+) and negative (δ-) charges in the covalent molecule) such as water , as thus the sea is salty as it accumulates dissolved salts since early geological ages. The solubility is favored by entropy of mixing (Δ S ) and depends on enthalpy of dissolution (Δ H ) and

1296-510: A solid or liquid can be "dissolved" in a gas only by passing into the gaseous state first. The solubility mainly depends on the composition of solute and solvent (including their pH and the presence of other dissolved substances) as well as on temperature and pressure. The dependency can often be explained in terms of interactions between the particles ( atoms , molecules , or ions ) of the two substances, and of thermodynamic concepts such as enthalpy and entropy . Under certain conditions,

1368-463: A solute's different solubilities in hot and cold solvent. A few exceptions exist, such as certain cyclodextrins . For condensed phases (solids and liquids), the pressure dependence of solubility is typically weak and usually neglected in practice. Assuming an ideal solution , the dependence can be quantified as: where the index i {\displaystyle i} iterates the components, N i {\displaystyle N_{i}}

1440-449: A solvent depends primarily on its polarity . For example, a very polar ( hydrophilic ) solute such as urea is very soluble in highly polar water, less soluble in fairly polar methanol , and practically insoluble in non-polar solvents such as benzene . In contrast, a non-polar or lipophilic solute such as naphthalene is insoluble in water, fairly soluble in methanol, and highly soluble in non-polar benzene. In even more simple terms

1512-427: A substance in a liquid may also be expressed as the quantity of solute per quantity of solution , rather than of solvent. For example, following the common practice in titration , it may be expressed as moles of solute per litre of solution (mol/L), the molarity of the latter. In more specialized contexts the solubility may be given by the mole fraction (moles of solute per total moles of solute plus solvent) or by

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1584-698: Is trimethyl phosphate , (CH 3 ) 3 PO 4 . The term also refers to the trivalent functional group OP(O-) 3 in such esters. Phosphates may contain sulfur in place of one or more oxygen atoms ( thiophosphates and organothiophosphates ). Orthophosphates are especially important among the various phosphates because of their key roles in biochemistry , biogeochemistry , and ecology , and their economic importance for agriculture and industry. The addition and removal of phosphate groups ( phosphorylation and dephosphorylation ) are key steps in cell metabolism . Orthophosphates can condense to form pyrophosphates . The phosphate ion has

1656-432: Is about half of its value at 25 °C. The dissolution of calcium hydroxide in water is also an exothermic process (Δ H  < 0). As dictated by the van 't Hoff equation and Le Chatelier's principle , lowe temperatures favorsf dissolution of Ca(OH) 2 . Portlandite solubility increases at low temperature. This temperature dependence is sometimes referred to as "retrograde" or "inverse" solubility. Occasionally,

1728-489: Is an anion , salt , functional group or ester derived from a phosphoric acid . It most commonly means orthophosphate , a derivative of orthophosphoric acid, a.k.a. phosphoric acid H 3 PO 4 . The phosphate or orthophosphate ion [PO 4 ] is derived from phosphoric acid by the removal of three protons H . Removal of one proton gives the dihydrogen phosphate ion [H 2 PO 4 ] while removal of two protons gives

1800-399: Is defined for specific phases . For example, the solubility of aragonite and calcite in water are expected to differ, even though they are both polymorphs of calcium carbonate and have the same chemical formula . The solubility of one substance in another is determined by the balance of intermolecular forces between the solvent and solute, and the entropy change that accompanies

1872-667: Is equal to the solubility of the substance. When the dissolution rate of a pure substance is normalized to the surface area of the solid (which usually changes with time during the dissolution process), then it is expressed in kg/m s and referred to as "intrinsic dissolution rate". The intrinsic dissolution rate is defined by the United States Pharmacopeia . Dissolution rates vary by orders of magnitude between different systems. Typically, very low dissolution rates parallel low solubilities, and substances with high solubilities exhibit high dissolution rates, as suggested by

1944-1340: Is generally denoted P i and at physiological ( homeostatic ) pH primarily consists of a mixture of [HPO 4 ] and [H 2 PO 4 ] ions. At a neutral pH, as in the cytosol (pH = 7.0), the concentrations of the orthophoshoric acid and its three anions have the ratios [ H 2 PO 4 − ] [ H 3 PO 4 ] ≈ 7.5 × 10 4 [ HPO 4 2 − ] [ H 2 PO 4 − ] ≈ 0.62 [ PO 4 3 − ] [ HPO 4 2 − ] ≈ 2.14 × 10 − 6 {\displaystyle {\begin{aligned}{\frac {[{\ce {H2PO4-}}]}{[{\ce {H3PO4}}]}}&\approx 7.5\times 10^{4}\\[4pt]{\frac {[{\ce {HPO4^2-}}]}{[{\ce {H2PO4-}}]}}&\approx 0.62\\[4pt]{\frac {[{\ce {PO4^3-}}]}{[{\ce {HPO4^2-}}]}}&\approx 2.14\times 10^{-6}\end{aligned}}} Thus, only [H 2 PO 4 ] and [HPO 4 ] ions are present in significant amounts in

2016-433: Is less than 0.1 g per 100 mL of solvent. Solubility occurs under dynamic equilibrium, which means that solubility results from the simultaneous and opposing processes of dissolution and phase joining (e.g. precipitation of solids ). A stable state of the solubility equilibrium occurs when the rates of dissolution and re-joining are equal, meaning the relative amounts of dissolved and non-dissolved materials are equal. If

2088-497: Is not an instantaneous process. The rate of solubilization (in kg/s) is related to the solubility product and the surface area of the material. The speed at which a solid dissolves may depend on its crystallinity or lack thereof in the case of amorphous solids and the surface area (crystallite size) and the presence of polymorphism . Many practical systems illustrate this effect, for example in designing methods for controlled drug delivery . In some cases, solubility equilibria can take

2160-408: Is observed to be almost an order of magnitude higher (i.e. about ten times higher) when the redox potential is controlled using a highly oxidizing Fe 3 O 4 -Fe 2 O 3 redox buffer than with a moderately oxidizing Ni - NiO buffer. Solubility (metastable, at concentrations approaching saturation) also depends on the physical size of the crystal or droplet of solute (or, strictly speaking, on

2232-416: Is the ability of a substance , the solute , to form a solution with another substance, the solvent . Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubility of a substance in a specific solvent is generally measured as the concentration of the solute in a saturated solution, one in which no more solute can be dissolved. At this point,

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2304-434: Is the mole fraction of the i {\displaystyle i} -th component in the solution, P {\displaystyle P} is the pressure, the index T {\displaystyle T} refers to constant temperature, V i , a q {\displaystyle V_{i,aq}} is the partial molar volume of the i {\displaystyle i} -th component in

2376-421: Is the partial pressure (in atm), and c {\displaystyle c} is the concentration of the dissolved gas in the liquid (in mol/L). The solubility of gases is sometimes also quantified using Bunsen solubility coefficient . In the presence of small bubbles , the solubility of the gas does not depend on the bubble radius in any other way than through the effect of the radius on pressure (i.e.

2448-401: Is typically rare can have significant ecological consequences. For example, blooms in the populations of some organisms at the expense of others, and the collapse of populations deprived of resources such as oxygen (see eutrophication ) can occur. In the context of pollution, phosphates are one component of total dissolved solids , a major indicator of water quality, but not all phosphorus is in

2520-480: Is used to quantify the solubility of gases in solvents. The solubility of a gas in a solvent is directly proportional to the partial pressure of that gas above the solvent. This relationship is similar to Raoult's law and can be written as: where k H {\displaystyle k_{\rm {H}}} is a temperature-dependent constant (for example, 769.2 L · atm / mol for dioxygen (O 2 ) in water at 298 K), p {\displaystyle p}

2592-409: The arbuscular mycorrhizal pathway and the direct uptake pathway. Hyperphosphatemia , or a high blood level of phosphates, is associated with elevated mortality in the general population. The most common cause of hyperphosphatemia in people, dogs, and cats is kidney failure. In cases of hyperphosphatemia, limiting consumption of phosphate-rich foods, such as some meats and dairy items and foods with

2664-497: The critical temperature ), the solubility of ionic solutes tends to decrease due to the change of properties and structure of liquid water; the lower dielectric constant results in a less polar solvent and in a change of hydration energy affecting the Δ G of the dissolution reaction. Gaseous solutes exhibit more complex behavior with temperature. As the temperature is raised, gases usually become less soluble in water (exothermic dissolution reaction related to their hydration) (to

2736-399: The hydrogen phosphate ion [HPO 4 ] . These names are also used for salts of those anions, such as ammonium dihydrogen phosphate and trisodium phosphate . In organic chemistry , phosphate or orthophosphate is an organophosphate , an ester of orthophosphoric acid of the form PO 4 RR′R″ where one or more hydrogen atoms are replaced by organic groups. An example

2808-485: The hydrophobic effect . The free energy of dissolution ( Gibbs energy ) depends on temperature and is given by the relationship: Δ G = Δ H – TΔ S . Smaller Δ G means greater solubility. Chemists often exploit differences in solubilities to separate and purify compounds from reaction mixtures, using the technique of liquid-liquid extraction . This applies in vast areas of chemistry from drug synthesis to spent nuclear fuel reprocessing. Dissolution

2880-606: The hydroxyl groups have been replaced by fluoride ions. Phosphates are medicinal salts of phosphorus. Some phosphates, which help cure many urinary tract infections , are used to make urine more acidic. To avoid the development of calcium stones in the urinary tract, some phosphates are used. For patients who are unable to get enough phosphorus in their daily diet, phosphates are used as dietary supplements, usually because of certain disorders or diseases. Injectable phosphates can only be handled by qualified health care providers. Plants take up phosphorus through several pathways:

2952-427: The mass fraction at equilibrium (mass of solute per mass of solute plus solvent). Both are dimensionless numbers between 0 and 1 which may be expressed as percentages (%). For solutions of liquids or gases in liquids, the quantities of both substances may be given volume rather than mass or mole amount; such as litre of solute per litre of solvent, or litre of solute per litre of solution. The value may be given as

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3024-442: The phosphagens in muscle tissue. Similar reactions exist for the other nucleoside diphosphates and triphosphates . An important occurrence of phosphates in biological systems is as the structural material of bone and teeth. These structures are made of crystalline calcium phosphate in the form of hydroxyapatite . The hard dense enamel of mammalian teeth may contain fluoroapatite , a hydroxy calcium phosphate where some of

3096-412: The reagents have been dissolved in a suitable solvent. Water is by far the most common such solvent. The term "soluble" is sometimes used for materials that can form colloidal suspensions of very fine solid particles in a liquid. The quantitative solubility of such substances is generally not well-defined, however. The solubility of a specific solute in a specific solvent is generally expressed as

3168-522: The specific surface area or molar surface area of the solute). For quantification, see the equation in the article on solubility equilibrium . For highly defective crystals, solubility may increase with the increasing degree of disorder. Both of these effects occur because of the dependence of solubility constant on the Gibbs energy of the crystal. The last two effects, although often difficult to measure, are of practical importance. For example, they provide

3240-495: The Earth orbit and its rotation axis progressively change and modify the solar irradiance at the Earth surface, temperature starts to increase. When a deglaciation period is initiated, the progressive warming of the oceans releases CO 2 into the atmosphere because of its lower solubility in warmer sea water. In turn, higher levels of CO 2 in the atmosphere increase the greenhouse effect and carbon dioxide acts as an amplifier of

3312-468: The Noyes-Whitney equation. Solubility constants are used to describe saturated solutions of ionic compounds of relatively low solubility (see solubility equilibrium ). The solubility constant is a special case of an equilibrium constant . Since it is a product of ion concentrations in equilibrium, it is also known as the solubility product . It describes the balance between dissolved ions from

3384-604: The United States) account for about 70% of world production. In ecological terms, because of its important role in biological systems, phosphate is a highly sought after resource. Once used, it is often a limiting nutrient in environments , and its availability may govern the rate of growth of organisms. This is generally true of freshwater environments, whereas nitrogen is more often the limiting nutrient in marine (seawater) environments. Addition of high levels of phosphate to environments and to micro-environments in which it

3456-400: The acid is completely dissociated as the phosphate ion, (PO 4 ) . This means that salts of the mono- and di-phosphate ions can be selectively crystallised from aqueous solution by setting the pH value to either 4.7 or 9.8. In effect, H 3 PO 4 , H 2 (PO 4 ) and H(PO 4 ) behave as separate weak acids because the successive p K

3528-641: The average phosphate rock has roughly 3.7% phosphorus by weight. Some phosphate rock deposits, such as Mulberry in Florida, are notable for their inclusion of significant quantities of radioactive uranium isotopes. This is a concern because radioactivity can be released into surface waters from application of the resulting phosphate fertilizer . In December 2012, Cominco Resources announced an updated JORC compliant resource of their Hinda project in Congo-Brazzaville of 531 million tons, making it

3600-552: The average rock (while, for perspective, its typical concentration in vegetation is 0.03% to 0.2%), and consequently there are quadrillions of tons of phosphorus in Earth's 3×10 -ton crust, albeit at predominantly lower concentration than the deposits counted as reserves, which are inventoried and cheaper to extract. If it is assumed that the phosphate minerals in phosphate rock are mainly hydroxyapatite and fluoroapatite, phosphate minerals contain roughly 18.5% phosphorus by weight. If phosphate rock contains around 20% of these minerals,

3672-472: The best quality, have been mined excessively. Rock phosphate can also be found in Egypt, Israel, Palestine, Western Sahara, Navassa Island , Tunisia, Togo, and Jordan, countries that have large phosphate-mining industries. Phosphorite mines are primarily found in: In 2007, at the current rate of consumption, the supply of phosphorus was estimated to run out in 345 years. However, some scientists thought that

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3744-791: The concentration of a saturated solution of the two. Any of the several ways of expressing concentration of solutions can be used, such as the mass , volume , or amount in moles of the solute for a specific mass, volume, or mole amount of the solvent or of the solution. In particular, chemical handbooks often express the solubility as grams of solute per 100 millilitres of solvent (g/(100 mL), often written as g/100 ml), or as grams of solute per decilitre of solvent (g/dL); or, less commonly, as grams of solute per litre of solvent (g/L). The quantity of solvent can instead be expressed in mass, as grams of solute per 100 grams of solvent (g/(100 g), often written as g/100 g), or as grams of solute per kilogram of solvent (g/kg). The number may be expressed as

3816-471: The concentration of the solute can exceed its usual solubility limit. The result is a supersaturated solution , which is metastable and will rapidly exclude the excess solute if a suitable nucleation site appears. The concept of solubility does not apply when there is an irreversible chemical reaction between the two substances, such as the reaction of calcium hydroxide with hydrochloric acid ; even though one might say, informally, that one "dissolved"

3888-404: The cytosol (62% [H 2 PO 4 ] , 38% [HPO 4 ] ). In extracellular fluid (pH = 7.4), this proportion is inverted (61% [HPO 4 ] , 39% [H 2 PO 4 ] ). Inorganic phosphate can also be present as pyrophosphate anions [P 2 O 7 ] , which give orthophosphate by hydrolysis : Organic phosphates are commonly found in

3960-402: The driving force for precipitate aging (the crystal size spontaneously increasing with time). The solubility of a given solute in a given solvent is function of temperature. Depending on the change in enthalpy (Δ H ) of the dissolution reaction, i.e. , on the endothermic (Δ H  > 0) or exothermic (Δ H  < 0) character of the dissolution reaction, the solubility of

4032-493: The extent of solubility for a given application. For example, U.S. Pharmacopoeia gives the following terms, according to the mass m sv of solvent required to dissolve one unit of mass m su of solute: (The solubilities of the examples are approximate, for water at 20–25 °C.) The thresholds to describe something as insoluble, or similar terms, may depend on the application. For example, one source states that substances are described as "insoluble" when their solubility

4104-502: The form of esters as nucleotides (e.g. AMP , ADP , and ATP ) and in DNA and RNA . Free orthophosphate anions can be released by the hydrolysis of the phosphoanhydride bonds in ATP or ADP. These phosphorylation and dephosphorylation reactions are the immediate storage and source of energy for many metabolic processes. ATP and ADP are often referred to as high-energy phosphates , as are

4176-483: The general warming. A popular aphorism used for predicting solubility is " like dissolves like " also expressed in the Latin language as " Similia similibus solventur ". This statement indicates that a solute will dissolve best in a solvent that has a similar chemical structure to itself, based on favorable entropy of mixing . This view is simplistic, but it is a useful rule of thumb. The overall solvation capacity of

4248-467: The largest measured and indicated phosphate deposit in the world. Around 2018, Norway discovered phosphate deposits almost equal to those in the rest of Earth combined. In July 2022 China announced quotas on phosphate exportation. The largest importers in millions of metric tons of phosphate are Brazil 3.2, India 2.9 and the USA 1.6. The three principal phosphate producer countries (China, Morocco and

4320-672: The other. The solubility is also not the same as the rate of solution , which is how fast a solid solute dissolves in a liquid solvent. This property depends on many other variables, such as the physical form of the two substances and the manner and intensity of mixing. The concept and measure of solubility are extremely important in many sciences besides chemistry, such as geology , biology , physics , and oceanography , as well as in engineering , medicine , agriculture , and even in non-technical activities like painting , cleaning , cooking , and brewing . Most chemical reactions of scientific, industrial, or practical interest only happen after

4392-401: The phosphoric acid is practically undissociated. Around pH 4.7 (mid-way between the first two p K a values) the dihydrogen phosphate ion, [H 2 PO 4 ] , is practically the only species present. Around pH 9.8 (mid-way between the second and third p K a values) the monohydrogen phosphate ion, [HPO 4 ] , is the only species present. At pH 13 or higher,

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4464-405: The salt and undissolved salt. The solubility constant is also "applicable" (i.e. useful) to precipitation , the reverse of the dissolving reaction. As with other equilibrium constants, temperature can affect the numerical value of solubility constant. While the solubility constant is not as simple as solubility, the value of this constant is generally independent of the presence of other species in

4536-414: The solubility of gas in the liquid in contact with small bubbles is increased due to pressure increase by Δ p  = 2γ/ r ; see Young–Laplace equation ). Henry's law is valid for gases that do not undergo change of chemical speciation on dissolution. Sieverts' law shows a case when this assumption does not hold. The carbon dioxide solubility in seawater is also affected by temperature, pH of

4608-483: The solubility per mole of solution is usually computed and quoted as if the solute does not dissociate or form complexes—that is, by pretending that the mole amount of solution is the sum of the mole amounts of the two substances. The extent of solubility ranges widely, from infinitely soluble (without limit, i.e. miscible ) such as ethanol in water, to essentially insoluble, such as titanium dioxide in water. A number of other descriptive terms are also used to qualify

4680-453: The solute is not recovered upon evaporation of the solvent, the process is referred to as solvolysis. The thermodynamic concept of solubility does not apply straightforwardly to solvolysis. When a solute dissolves, it may form several species in the solution. For example, an aqueous solution of cobalt(II) chloride can afford [Co(H 2 O) 6 ] , [CoCl(H 2 O) 5 ] , CoCl 2 (H 2 O) 2 , each of which interconverts. Solubility

4752-587: The solution, V i , c r {\displaystyle V_{i,cr}} is the partial molar volume of the i {\displaystyle i} -th component in the dissolving solid, and R {\displaystyle R} is the universal gas constant . The pressure dependence of solubility does occasionally have practical significance. For example, precipitation fouling of oil fields and wells by calcium sulfate (which decreases its solubility with decreasing pressure) can result in decreased productivity with time. Henry's law

4824-573: The solution, and by the carbonate buffer. The decrease of solubility of carbon dioxide in seawater when temperature increases is also an important retroaction factor (positive feedback) exacerbating past and future climate changes as observed in ice cores from the Vostok site in Antarctica . At the geological time scale, because of the Milankovich cycles , when the astronomical parameters of

4896-409: The solvation. Factors such as temperature and pressure will alter this balance, thus changing the solubility. Solubility may also strongly depend on the presence of other species dissolved in the solvent, for example, complex-forming anions ( ligands ) in liquids. Solubility will also depend on the excess or deficiency of a common ion in the solution , a phenomenon known as the common-ion effect . To

4968-415: The solvent and the sum of the two volumes. Moreover, many solids (such as acids and salts ) will dissociate in non-trivial ways when dissolved; conversely, the solvent may form coordination complexes with the molecules or ions of the solute. In those cases, the sum of the moles of molecules of solute and solvent is not really the total moles of independent particles solution. To sidestep that problem,

5040-441: The solvent is removed, all of the substance that had dissolved is recovered. The term solubility is also used in some fields where the solute is altered by solvolysis . For example, many metals and their oxides are said to be "soluble in hydrochloric acid", although in fact the aqueous acid irreversibly degrades the solid to give soluble products. Most ionic solids dissociate when dissolved in polar solvents. In those cases where

5112-476: The two substances are said to be at the solubility equilibrium . For some solutes and solvents, there may be no such limit, in which case the two substances are said to be " miscible in all proportions" (or just "miscible"). The solute can be a solid , a liquid , or a gas , while the solvent is usually solid or liquid. Both may be pure substances, or may themselves be solutions. Gases are always miscible in all proportions, except in very extreme situations, and

5184-401: Was exposed to failed Icelandic banks, and drawdowns were made by the government of Kiribati to finance budgetary shortfalls. In 2018, it is set to reach 1 billion of A$ . In 2019, the closing market value of the RERF was A$ 1,153.4 million. This Republic of Kiribati -related article is a stub . You can help Misplaced Pages by expanding it . Phosphate In chemistry , a phosphate

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