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78-469: Café HAG is a worldwide brand of decaffeinated coffee currently owned by JDE Peet's . Café HAG was founded in Bremen in 1906 as Kaffee-Handels-Aktiengesellschaft (Coffee Trading Limited). The company's founder was Ludwig Roselius , who codeveloped the first commercial decaffeination process. Alfred Runge and Eduard Scotland designed posters and packaging, and are credited with designs that defined

156-422: A q − H i , c r R T 2 {\displaystyle \left({\frac {\partial \ln x_{i}}{\partial T}}\right)_{P}={\frac {{\bar {H}}_{i,\mathrm {aq} }-H_{i,\mathrm {cr} }}{RT^{2}}}} where H ¯ i , a q {\displaystyle {\bar {H}}_{i,\mathrm {aq} }} is the partial molar enthalpy of

234-446: A q − V i , c r R T {\displaystyle \left({\frac {\partial \ln x_{i}}{\partial P}}\right)_{T}=-{\frac {{\bar {V}}_{i,\mathrm {aq} }-V_{i,\mathrm {cr} }}{RT}}} where x i {\displaystyle x_{i}} is the mole fraction of the i {\displaystyle i} -th component in the solution, P {\displaystyle P}

312-888: A q ) {\displaystyle \mathrm {AgCl(s)\leftrightharpoons Ag^{+}(aq)+Cl^{-}(aq)} } The solubility, S , in the absence of a common ion can be calculated as follows. The concentrations [Ag ] and [Cl ] are equal because one mole of AgCl would dissociate into one mole of Ag and one mole of Cl . Let the concentration of [Ag (aq)] be denoted by x . Then K s p = [ A g + ] [ C l − ] = x 2 {\displaystyle K_{\mathrm {sp} }=\mathrm {[Ag^{+}][Cl^{-}]} =x^{2}} Solubility = [ A g + ] = [ C l − ] = x = K s p {\displaystyle {\text{Solubility}}=\mathrm {[Ag^{+}]=[Cl^{-}]} =x={\sqrt {K_{\mathrm {sp} }}}} K sp for AgCl

390-424: A q ) ] {\displaystyle K_{\mathrm {s} }=\left[\mathrm {{C}_{12}{H}_{22}{O}_{11}(aq)} \right]} is obtained. This is equivalent to defining the standard state as the saturated solution so that the activity coefficient is equal to one. The solubility constant is a true constant only if the activity coefficient is not affected by the presence of any other solutes that may be present. The unit of

468-439: A q ) } {\displaystyle K^{\ominus }=\left\{\mathrm {{C}_{12}{H}_{22}{O}_{11}(aq)} \right\}} The activity of a substance, A, in solution can be expressed as the product of the concentration, [A], and an activity coefficient , γ . When K is divided by γ , the solubility constant, K s , K s = [ C 12 H 22 O 11 (

546-568: A q ) } { C 12 H 22 O 11 ( s ) } {\displaystyle K^{\ominus }={\frac {\left\{\mathrm {{C}_{12}{H}_{22}{O}_{11}(aq)} \right\}}{\left\{\mathrm {{C}_{12}{H}_{22}{O}_{11}(s)} \right\}}}} where K is called the thermodynamic solubility constant. The braces indicate activity . The activity of a pure solid is, by definition, unity. Therefore K ⊖ = { C 12 H 22 O 11 (

624-447: A q ) + C l − ( a q ) {\displaystyle \mathrm {AgCl(s)+2NH_{3}(aq)\leftrightharpoons [Ag(NH_{3})_{2}]^{+}(aq)+Cl^{-}(aq)} } When sufficient ammonia is added to a suspension of silver chloride, the solid dissolves. The addition of water softeners to washing powders to inhibit the formation of soap scum provides an example of practical importance. The determination of solubility

702-429: A chemical complex may also change solubility. A well-known example is the addition of a concentrated solution of ammonia to a suspension of silver chloride , in which dissolution is favoured by the formation of an ammine complex. A g C l ( s ) + 2 N H 3 ( a q ) ⇋ [ A g ( N H 3 ) 2 ] + (

780-410: A considerable reduction from 1.33 × 10  mol dm . In gravimetric analysis for silver, the reduction in solubility due to the common ion effect is used to ensure "complete" precipitation of AgCl. The thermodynamic solubility constant is defined for large monocrystals. Solubility will increase with decreasing size of solute particle (or droplet) because of the additional surface energy. This effect

858-425: A hot water treatment. Optimal conditions are met by controlling water temperature, extraction time, and ratio of leaf to water. Temperatures of 100 °C or more, moderate extraction time of 3 minutes, and a 1:20 leaf to water weight per volume ratio removed 83% caffeine content and preserved 95% of total catechins . Catechins, a type of flavanol , contribute to the flavor of the tea and have been shown to increase

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936-415: A mixture is brought to equilibrium and the concentration of a species in the solution phase is determined by chemical analysis . This usually requires separation of the solid and solution phases. In order to do this the equilibration and separation should be performed in a thermostatted room. Very low concentrations can be measured if a radioactive tracer is incorporated in the solid phase. A variation of

1014-935: A modified form, K * sp , using hydrogen ion concentration in place of hydroxide ion concentration. The two values are related by the self-ionization constant for water, K w . K w = [ H + ] [ O H − ] {\displaystyle K_{\mathrm {w} }=[\mathrm {H^{+}} ][\mathrm {OH^{-}} ]} K sp ∗ = K sp ( K w ) n {\displaystyle K_{\text{sp}}^{*}={\frac {K_{\text{sp}}}{(K_{\text{w}})^{n}}}} log ⁡ K sp ∗ = log ⁡ K sp − n log ⁡ K w {\displaystyle \log K_{\text{sp}}^{*}=\log K_{\text{sp}}-n\log K_{\text{w}}} For example, at ambient temperature, for calcium hydroxide, Ca(OH) 2 , lg K sp

1092-401: A process called "Chasing equilibrium solubility". In this procedure, a quantity of substance is first dissolved at a pH where it exists predominantly in its ionized form and then a precipitate of the neutral (un-ionized) species is formed by changing the pH. Subsequently, the rate of change of pH due to precipitation or dissolution is monitored and strong acid and base titrant are added to adjust

1170-430: A quotient of concentrations. See Equilibrium chemistry#Equilibrium constant for details. Moreover, the activity of a solid is, by definition, equal to 1 so it is omitted from the defining expression. For a chemical equilibrium A p B q ⇋ p A + q B {\displaystyle \mathrm {A} _{p}\mathrm {B} _{q}\leftrightharpoons p\mathrm {A} +q\mathrm {B} }

1248-503: Is a direct-contact method of decaffeination. Food scientists have also turned to supercritical carbon dioxide (sCO 2 ) as a means of decaffeination. Developed by Kurt Zosel, a scientist of the Max Planck Institute, it uses CO 2 (carbon dioxide), heated and pressurised above its critical point , to extract caffeine. Green coffee beans are steamed and then added to a high pressure vessel. A mixture of water and CO 2

1326-769: Is a quadratic equation in x , which is also equal to the solubility. x 2 + 0.01 M x − K s p = 0 {\displaystyle x^{2}+0.01\,{\text{M}}\,x-K_{sp}=0} In the case of silver chloride, x is very much smaller than 0.01 M x , so the first term can be ignored. Therefore Solubility = [ A g + ] = x = K s p 0.01 M = 1.77 × 10 − 8 m o l d m − 3 {\displaystyle {\text{Solubility}}=\mathrm {[Ag^{+}]} =x={\frac {K_{\mathrm {sp} }}{0.01\,{\text{M}}}}=\mathrm {1.77\times 10^{-8}\,mol\,dm^{-3}} }

1404-461: Is ca. −5 and lg K * sp ≈ −5 + 2 × 14 ≈ 23. A typical reaction with dissolution involves a weak base , B, dissolving in an acidic aqueous solution . B ( s ) + H + ( a q ) ⇋ B H + ( a q ) {\displaystyle \mathrm {B} \mathrm {(s)} +\mathrm {H} ^{+}\mathrm {(aq)} \leftrightharpoons \mathrm {BH} ^{+}(\mathrm {aq)} } This reaction

1482-682: Is calculated by the method outlined in dissolution with reaction . The solubility product for the hydroxide of a metal ion, M , is usually defined, as follows: M ( O H ) n ⇋ M n + + n O H − {\displaystyle \mathrm {M(OH)_{n}\leftrightharpoons \mathrm {M^{n+}+nOH^{-}} } } K s p = [ M n + ] [ O H − ] n {\displaystyle K_{sp}=\mathrm {[M^{n+}][OH^{-}]^{n}} } However, general-purpose computer programs are designed to use hydrogen ion concentrations with

1560-448: Is circulated through the vessel at 300 atm and 65 °C (149 °F). At this pressure and temperature CO 2 is a supercritical fluid , with properties midway between a gas and a liquid. Caffeine dissolves into the CO 2 ; but compounds contributing to the flavour of the brewed coffee are largely insoluble in CO 2 and remain in the bean. In a separate vessel, caffeine is scrubbed from

1638-559: Is equal to 1.77 × 10  mol dm at 25 °C, so the solubility is 1.33 × 10  mol dm . Now suppose that sodium chloride is also present, at a concentration of 0.01 mol dm = 0.01 M. The solubility, ignoring any possible effect of the sodium ions, is now calculated by K s p = [ A g + ] [ C l − ] = x ( 0.01 M + x ) {\displaystyle K_{\mathrm {sp} }=\mathrm {[Ag^{+}][Cl^{-}]} =x(0.01\,{\text{M}}+x)} This

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1716-515: Is fraught with difficulties. First and foremost is the difficulty in establishing that the system is in equilibrium at the chosen temperature. This is because both precipitation and dissolution reactions may be extremely slow. If the process is very slow solvent evaporation may be an issue. Supersaturation may occur. With very insoluble substances, the concentrations in solution are very low and difficult to determine. The methods used fall broadly into two categories, static and dynamic. In static methods

1794-536: Is generally small unless particles become very small, typically smaller than 1 μm. The effect of the particle size on solubility constant can be quantified as follows: log ⁡ ( ∗ K A ) = log ⁡ ( ∗ K A → 0 ) + γ A m 3.454 R T {\displaystyle \log(^{*}K_{A})=\log(^{*}K_{A\to 0})+{\frac {\gamma A_{\mathrm {m} }}{3.454RT}}} where * K A

1872-403: Is known as the solubility . Units of solubility may be molar (mol dm ) or expressed as mass per unit volume, such as μg mL . Solubility is temperature dependent. A solution containing a higher concentration of solute than the solubility is said to be supersaturated . A supersaturated solution may be induced to come to equilibrium by the addition of a "seed" which may be a tiny crystal of

1950-415: Is that a cup of normal black (or red) tea contains 40–50 mg of caffeine, roughly half the content of a cup of coffee. Although a common technique of discarding a short (30 to 60 seconds) steep is believed to much reduce caffeine content of a subsequent brew at the cost of some loss of flavor, research suggests that a five-minute steep yields up to 70% of the caffeine, and a second steep has one-third

2028-438: Is the basis for the process of recrystallization , which can be used to purify a chemical compound. When dissolution is exothermic (heat is released) solubility decreases with rising temperature. Sodium sulfate shows increasing solubility with temperature below about 32.4 °C, but a decreasing solubility at higher temperature. This is because the solid phase is the decahydrate ( Na 2 SO 4 ·10H 2 O ) below

2106-429: Is the effect of decreased solubility of one salt when another salt that has an ion in common with it is also present. For example, the solubility of silver chloride , AgCl, is lowered when sodium chloride, a source of the common ion chloride, is added to a suspension of AgCl in water. A g C l ( s ) ⇋ A g + ( a q ) + C l − (

2184-555: 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. Dissolution of an organic solid can be described as an equilibrium between

2262-409: Is the pressure, T {\displaystyle T} is the absolute temperature, V ¯ i , aq {\displaystyle {\bar {V}}_{i,{\text{aq}}}} is the partial molar volume of the i {\displaystyle i} th component in the solution, V i , cr {\displaystyle V_{i,{\text{cr}}}}

2340-487: Is the solubility constant for the solute particles with the molar surface area A , * K A →0 is the solubility constant for substance with molar surface area tending to zero (i.e., when the particles are large), γ is the surface tension of the solute particle in the solvent, A m is the molar surface area of the solute (in m /mol), R is the universal gas constant , and T is the absolute temperature . The salt effects ( salting in and salting-out ) refers to

2418-754: Is the thermodynamic equilibrium constant and braces indicate activity. The activity of a pure solid is, by definition, equal to one. When the solubility of the salt is very low the activity coefficients of the ions in solution are nearly equal to one. By setting them to be actually equal to one this expression reduces to the solubility product expression: K sp = [ Ag + ] [ Cl − ] = [ Ag + ] 2 = [ Cl − ] 2 . {\displaystyle K_{{\ce {sp}}}=[{\ce {Ag+}}][{\ce {Cl-}}]=[{\ce {Ag+}}]^{2}=[{\ce {Cl-}}]^{2}.} For 2:2 and 3:3 salts, such as CaSO 4 and FePO 4 ,

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2496-400: Is then said to be in a metastable state. In pharmacology, the metastable state is sometimes referred to as amorphous state. Amorphous drugs have higher solubility than their crystalline counterparts due to the absence of long-distance interactions inherent in crystal lattice. Thus, it takes less energy to solvate the molecules in amorphous phase. The effect of amorphous phase on solubility

2574-445: Is very important for pharmaceutical products. Dissolution of weak acids in alkaline media is similarly important. H A ( s ) + O H − ( a q ) ⇋ A − ( a q ) + H 2 O {\displaystyle \mathrm {HA(s)+OH^{-}(aq)\leftrightharpoons A^{-}(aq)+H_{2}O} } The uncharged molecule usually has lower solubility than

2652-433: Is widely used to make drugs more soluble. 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: ( ∂ ln ⁡ x i ∂ P ) T = − V ¯ i ,

2730-407: The activated carbon filters to remove the caffeine again, and the process is repeated. The continuous batch process takes 8–10 hours to meet the final residual decaffeinated target. Food engineer Torunn Atteraas Garin also developed a process to remove caffeine from coffee. In this process, green coffee beans are soaked in a hot water and coffee solution to draw the caffeine to the surface of

2808-439: The dimension of (concentration) . Solubility is sensitive to changes in temperature . For example, sugar is more soluble in hot water than cool water. It occurs because solubility products, like other types of equilibrium constants, are functions of temperature. In accordance with Le Chatelier's Principle , when the dissolution process is endothermic (heat is absorbed), solubility increases with rising temperature. This effect

2886-429: The direct organic solvent method . However, because of health concerns regarding benzene (which is recognized today as a carcinogen ), other solvents, such as dichloromethane or ethyl acetate , are now used. The unroasted (green) beans are first steamed and then rinsed with the solvent which extracts the caffeine, while leaving other constituents largely unaffected. The process is repeated between 8 and 12 times until

2964-508: The CO 2 process is favorable because it is convenient, nonexplosive, and nontoxic, a comparison between regular and decaffeinated green teas using supercritical carbon dioxide showed that most volatile, non polar compounds (such as linalool and phenylacetaldehyde ), green and floral flavor compounds (such as hexanal and ( E )-2- hexenal ), and some unknown compounds disappeared or decreased after decaffeination. In addition to CO 2 process extraction, tea may be also decaffeinated using

3042-630: The CO 2 with additional water. The CO 2 is then recirculated to the pressure vessel. To ensure product quality, manufacturers are required to test the newly decaffeinated coffee beans to make sure that caffeine concentration is relatively low. A caffeine content reduction of at least 97% is required under United States standards. There is less than 0.1% caffeine in decaffeinated coffee and less than 0.3% in decaffeinated instant coffee in Canada. Many coffee companies use high-performance liquid chromatography (HPLC) to measure how much caffeine remains in

3120-469: The GCE (which is caffeine-lean) and the green coffee (which is caffeine-rich) causes the caffeine molecules to migrate from the green coffee into the GCE. Because GCE is saturated with the other water-soluble components of green coffee, only the caffeine molecules migrate to the GCE; the other water-soluble coffee elements are retained in the green coffee. The newly caffeine-rich GCE solution is then passed through

3198-510: The UV-Vis range. A controlled study in 2006 at Florida State University of ten samples of prepared decaffeinated coffee from coffee shops showed that some caffeine remained. Fourteen to twenty cups of such decaffeinated coffee would contain as much caffeine as one cup of regular coffee. The 473 ml (16 ounce) cups of coffee samples contained caffeine in the range of 8.6 mg to 13.9 mg. In another study of popular brands of decaf coffees,

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3276-543: The alternative definitions. M ( O H ) n + n H + ⇋ M n + + n H 2 O {\displaystyle \mathrm {M(OH)_{n}+nH^{+}\leftrightharpoons M^{n+}+nH_{2}O} } K sp ∗ = [ M n + ] [ H + ] − n {\displaystyle K_{\text{sp}}^{*}=\mathrm {[M^{n+}][H^{+}]^{-n}} } For hydroxides, solubility products are often given in

3354-430: The beans, so no coffee strength or other flavorings are lost. Because water is used in the initial phase of this process, indirect method decaffeination is sometimes referred to as "water-processed". This method was first mentioned in 1941, and people have made significant efforts to make the process more "natural" and a true water-based process by finding ways to process the caffeine out of the water in ways that circumvent

3432-410: The beans, while leaving flavour precursors in as close to their original state as possible. The first commercially successful decaffeination process was invented by German merchant Ludwig Roselius and co-workers in 1903, after Roselius observed that a consignment of coffee beans accidentally soaked in sea water had lost most of their caffeine content while losing little of their flavour. The process

3510-446: The beans. Next, the beans are transferred to another container and immersed in coffee oils that were obtained from spent coffee grounds and left to soak. After several hours of high temperatures, the triglycerides in the oils remove the caffeine, but not the flavor elements, from the beans. The beans are separated from the oils and dried. The caffeine is removed from the oils, which are reused to decaffeinate another batch of beans. This

3588-556: The caffeine content meets the required standard (97% of caffeine removed according to the US standard, or 99.9% caffeine-free by mass per the EU standard). Another variation of Roselius' method is the indirect organic solvent method . In this method, instead of treating the beans directly, they are first soaked in hot water for several hours, then removed. The remaining water is treated with solvents (e.g. dichloromethane or ethyl acetate) to extract

3666-514: The caffeine content varied from 3 mg to 32 mg. In contrast, a 237 ml (8 ounce) cup of regular coffee contains 95–200 mg of caffeine, and a 355 ml (12 ounce) serving of Coca-Cola contains 36 mg. As of 2009, progress toward growing coffee beans that do not contain caffeine was still continuing. The term "Decaffito" has been coined to describe this type of coffee, and trademarked in Brazil. The prospect for Decaffito-type coffees

3744-430: The caffeine extraction mechanism. Green coffee extract is a solution containing the water-soluble components of green coffee except for the caffeine, obtained by soaking green coffee beans in hot water, then filtering through an activated charcoal filter to remove the caffeine molecules. Fresh beans containing both caffeine and the other components are added to the GCE solution, where the gradient pressure difference between

3822-415: The caffeine from the water. As in other methods, the caffeine can then be separated from the organic solvent by simple evaporation. The same water is recycled through this two-step process with new batches of beans. An equilibrium is reached after several cycles, wherein the water and the beans have a similar composition except for the caffeine. After this point, the caffeine is the only material removed from

3900-400: The caffeine of the first (about 23% of the total caffeine in the leaves). Solubility equilibrium Solubility equilibrium is a type of dynamic equilibrium that exists when a chemical compound in the solid state is in chemical equilibrium with a solution of that compound. The solid may dissolve unchanged, with dissociation, or with chemical reaction with another constituent of

3978-481: The coffee beans. However, since HPLC can be quite costly, some coffee companies are beginning to use other methods such as near-infrared (NIR) spectroscopy . Although HPLC is highly accurate, NIR spectroscopy is much faster, cheaper and overall easier to use. Lastly, another method typically used to measure the remaining caffeine includes ultraviolet–visible spectroscopy : useful for decaffeination processes that include supercritical CO 2 , as CO 2 does not absorb in

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4056-687: The company. In the 1920s and 1930s the company was known for the publication of the Café HAG albums of heraldic emblems. The coffee brand Sanka spun off from Café HAG in 1910 for the French market ("Sanka" is a contraction of sans caféine ), and American rights to the Sanka name were sold in 1913. The Kellogg Company purchased Roselius's American branch (based in Cleveland, Ohio ) in 1928, then sold it to General Foods in 1939. General Foods acquired

4134-405: The compound. This type of equilibrium is an example of dynamic equilibrium in that some individual molecules migrate between the solid and solution phases such that the rates of dissolution and precipitation are equal to one another. When equilibrium is established and the solid has not all dissolved, the solution is said to be saturated. The concentration of the solute in a saturated solution

4212-707: The concentration of hydroxide ions is twice the concentration of calcium ions this reduces to K s p = 4 [ C a ] 3 {\displaystyle \mathrm {K_{sp}=4[Ca]^{3}} } In general, with the chemical equilibrium A p B q   ⇋   p A n + + q B m − {\displaystyle {\ce {A}}_{p}{\ce {B}}_{q}~{\ce {\leftrightharpoons }}~p{\ce {A}}^{n+}+q{\ce {B}}^{m-}} [ B ] = q p [ A ] {\displaystyle {\ce {[B]}}={\frac {q}{p}}{\ce {[A]}}} and

4290-519: The direct method or the CO 2 process, as described above. Oxidizing tea leaves to create black tea ("red" in Chinese tea culture) or oolong tea leaves from green leaves does not affect the amount of caffeine in the tea, though tea-plant subspecies (i.e. Camellia sinensis sinensis vs. Camellia sinensis assamica ) may differ in natural caffeine content. Younger leaves and buds contain more caffeine by weight than older leaves and stems. Although

4368-783: The equilibrium constant for this reaction is: K ⊖ = { Ag + ( aq ) } { Cl − ( aq ) } { AgCl ( s ) } = { Ag + ( aq ) } { Cl − ( aq ) } {\displaystyle K^{\ominus }={\frac {\left\{{\ce {Ag+}}_{{\ce {(aq)}}}\right\}\left\{{\ce {Cl-}}_{{\ce {(aq)}}}\right\}}{\left\{{\ce {AgCl_{(s)}}}\right\}}}=\left\{{\ce {Ag+}}_{{\ce {(aq)}}}\right\}\left\{{\ce {Cl-}}_{{\ce {(aq)}}}\right\}} where K ⊖ {\displaystyle K^{\ominus }}

4446-400: The fact that the presence of a salt which has no ion in common with the solute, has an effect on the ionic strength of the solution and hence on activity coefficients , so that the equilibrium constant, expressed as a concentration quotient, changes. Equilibria are defined for specific crystal phases . Therefore, the solubility product is expected to be different depending on the phase of

4524-671: The first isolation of caffeine from coffee beans in 1820, after the German poet Goethe heard about his work on belladonna extract, and requested he perform an analysis on coffee beans. Though Runge was able to isolate the compound, he did not learn much about the chemistry of caffeine itself, nor did he seek to use the process commercially to produce decaffeinated coffee. Various methods can be used for decaffeination of coffee. These methods take place prior to roasting and may use organic solvents such as dichloromethane or ethyl acetate , supercritical CO 2 , or water to extract caffeine from

4602-639: The following table, showing the relationship between the solubility of a compound and the value of its solubility product, can be derived. Solubility products are often expressed in logarithmic form. Thus, for calcium sulfate, with K sp = 4.93 × 10 mol dm , log K sp = −4.32 . The smaller the value of K sp , or the more negative the log value, the lower the solubility. Some salts are not fully dissociated in solution. Examples include MgSO 4 , famously discovered by Manfred Eigen to be present in seawater as both an inner sphere complex and an outer sphere complex . The solubility of such salts

4680-847: The general expression for the solubility product is the same as for a 1:1 electrolyte A B ⇋ A p + + B p − {\displaystyle \mathrm {AB} \leftrightharpoons \mathrm {A} ^{p+}+\mathrm {B} ^{p-}} With an unsymmetrical salt like Ca(OH) 2 the solubility expression is given by Ca ( OH ) 2 ↽ − − ⇀ Ca 2 + + 2 OH − {\displaystyle {\ce {Ca(OH)_2 <=> {Ca}^{2+}+ 2OH^-}}} K s p = [ Ca ] [ OH ] 2 {\displaystyle K_{sp}={\ce {[Ca]}}{\ce {[OH]}}^{2}} Since

4758-448: The ionic form, so solubility depends on pH and the acid dissociation constant of the solute. The term "intrinsic solubility" is used to describe the solubility of the un-ionized form in the absence of acid or alkali. Leaching of aluminium salts from rocks and soil by acid rain is another example of dissolution with reaction: alumino-silicates are bases which react with the acid to form soluble species, such as Al (aq). Formation of

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4836-610: The original German company in 1979. In 1990 Kraft Foods merged with General Foods, thus HAG and Sanka became brands of the American company. The spelling Café HAG was standardized in the 1990s. HAG has been owned by JDE Peet's since 2015. Café HAG TV adverts were popular in the 1980s; in particular the character Klaus (played by Roger Callister) became something of a cult figure among advertisement aficionados. [REDACTED] Media related to Coffee Hag at Wikimedia Commons Decaffeination Friedlieb Ferdinand Runge performed

4914-418: The particles are so small that the particle size effect comes into play and kinetic solubility is often greater than equilibrium solubility. Over time the cloudiness will disappear as the size of the crystallites increases, and eventually equilibrium will be reached in a process known as precipitate ageing. Solubility values of organic acids, bases, and ampholytes of pharmaceutical interest may be obtained by

4992-444: The serum lipid level, and modulate immunoresponses. Certain processes during normal production might help to decrease the caffeine content directly, or simply lower the rate at which it is released throughout each infusion. In China, this is evident in many cooked pu-erh teas , as well as more heavily fired Wuyi Mountain oolongs; commonly referred to as 'zhonghuo' (mid-fired) or 'zuhuo' (high-fired). A generally accepted statistic

5070-437: The solid. For example, aragonite and calcite will have different solubility products even though they have both the same chemical identity ( calcium carbonate ). Under any given conditions one phase will be thermodynamically more stable than the other; therefore, this phase will form when thermodynamic equilibrium is established. However, kinetic factors may favor the formation the unfavorable precipitate (e.g. aragonite), which

5148-905: The solubility constant is the same as the unit of the concentration of the solute. For sucrose K s  = 1.971 mol dm at 25 °C. This shows that the solubility of sucrose at 25 °C is nearly 2 mol dm (540 g/L). Sucrose is unusual in that it does not easily form a supersaturated solution at higher concentrations, as do most other carbohydrates . Ionic compounds normally dissociate into their constituent ions when they dissolve in water. For example, for silver chloride : AgCl ( s ) ↽ − − ⇀ Ag ( aq ) + + Cl − ( aq ) {\displaystyle {\ce {AgCl_{(s)}<=> Ag^+_{(aq)}{}+ Cl^-_{(aq)}}}} The expression for

5226-463: The solubility product, K sp for the compound A p B q is defined as follows K s p = [ A ] p [ B ] q {\displaystyle K_{\mathrm {sp} }=[\mathrm {A} ]^{p}[\mathrm {B} ]^{q}} where [A] and [B] are the concentrations of A and B in a saturated solution . A solubility product has a similar functionality to an equilibrium constant though formally K sp has

5304-626: The solute at infinite dilution and H i , c r {\displaystyle H_{i,\mathrm {cr} }} the enthalpy per mole of the pure crystal. This differential expression for a non-electrolyte can be integrated on a temperature interval to give: ln ⁡ x i = Δ m H i R ( 1 T f − 1 T ) {\displaystyle \ln x_{i}={\frac {\Delta _{m}H_{i}}{R}}\left({\frac {1}{T_{f}}}-{\frac {1}{T}}\right)} For nonideal solutions activity of

5382-536: The solute at saturation appears instead of mole fraction solubility in the derivative with respect to temperature: ( ∂ ln ⁡ a i ∂ T ) P = H i , a q − H i , c r R T 2 {\displaystyle \left({\frac {\partial \ln a_{i}}{\partial T}}\right)_{P}={\frac {H_{i,\mathrm {aq} }-H_{i,\mathrm {cr} }}{RT^{2}}}} The common-ion effect

5460-447: The solute, or a tiny solid particle, which initiates precipitation. There are three main types of solubility equilibria. In each case an equilibrium constant can be specified as a quotient of activities . This equilibrium constant is dimensionless as activity is a dimensionless quantity. However, use of activities is very inconvenient, so the equilibrium constant is usually divided by the quotient of activity coefficients, to become

5538-411: The solution, such as acid or alkali. Each solubility equilibrium is characterized by a temperature-dependent solubility product which functions like an equilibrium constant . Solubility equilibria are important in pharmaceutical, environmental and many other scenarios. A solubility equilibrium exists when a chemical compound in the solid state is in chemical equilibrium with a solution containing

5616-457: The static method is to add a solution of the substance in a non-aqueous solvent, such as dimethyl sulfoxide , to an aqueous buffer mixture. Immediate precipitation may occur giving a cloudy mixture. The solubility measured for such a mixture is known as "kinetic solubility". The cloudiness is due to the fact that the precipitate particles are very small resulting in Tyndall scattering . In fact

5694-635: The substance in its solid and dissolved forms. For example, when sucrose (table sugar) forms a saturated solution C 12 H 22 O 11 ( s ) ⇋ C 12 H 22 O 11 ( a q ) {\displaystyle \mathrm {C_{12}H_{22}O_{11}(s)\leftrightharpoons C_{12}H_{22}O_{11}(aq)} } An equilibrium expression for this reaction can be written, as for any chemical reaction (products over reactants): K ⊖ = { C 12 H 22 O 11 (

5772-617: The suppression of mutagens that may lead to cancer. Both coffee and tea have tannins , which are responsible for their astringent taste, but tea has around one third of the tannin content of coffee. Thus, decaffeination of tea requires more care to maintain tannin content than decaffeination of coffee in order to preserve this flavor. Preserving tannins is desirable not only because of their flavor, but also because they have been shown to have anticarcinogenic, antimutagenic, antioxidative, and antimicrobial properties. Specifically, tannins accelerate blood clotting, reduce blood pressure, decrease

5850-558: The transition temperature, but a different hydrate above that temperature. The dependence on temperature of solubility for an ideal solution (achieved for low solubility substances) is given by the following expression containing the enthalpy of melting, Δ m H , and the mole fraction x i {\displaystyle x_{i}} of the solute at saturation: ( ∂ ln ⁡ x i ∂ T ) P = H ¯ i ,

5928-620: The use of organic solvents. An alternative method for removal of caffeine from coffee is the Swiss Water process. This process uses no organic solvents, and instead only water is used to decaffeinate beans. It is a technique first developed in Switzerland in 1933, and commercialized by Coffex S.A. in 1980. The Swiss Water process was then introduced by The Swiss Water Decaffeinated Coffee Company of Burnaby , British Columbia , in 1988. The process uses green coffee extract (GCE) for

6006-683: Was patented in 1906, and involved steaming coffee beans with various acids or bases , then using benzene as a solvent to remove the caffeine. Coffee decaffeinated this way was sold as Kaffee HAG after the company name Kaffee Handels-Aktien-Gesellschaft (Coffee Trading Company) in most of Europe, as Café Sanka in France and later as Sanka brand coffee in the United States . Café HAG and Sanka are now worldwide brands of Kraft Foods . Methods similar to those first developed by Roselius have continued to dominate, and are sometimes known as

6084-519: Was shown by the discovery of the naturally caffeine-free Coffea charrieriana variety, reported in 2004. It has a deficient caffeine synthase gene, leading it to accumulate theobromine instead of converting it to caffeine. Either this trait could be bred into other coffee plants by crossing them with C. charrieriana , or an equivalent effect could be achieved by knocking out the gene for caffeine synthase in normal coffee plants. Tea may also be decaffeinated, usually by using processes analogous to

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