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| {{Expert-subject|Chemistry|talk=Adding tags to indicate entirety of article unsourced or poorly sourced|reason=complete lack of expert content derived from secondary sources, and chosen with a broad scholarly view of the modern discipline|date=June 2015}} | |||
| {{Requires attention|for=repeated appearance of dubious, naive, and non-scholarly statements on the title subject|date=June 2015}} | |||
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| ] solution by dissolving ] (]) in ]. The salt is the solute and the water the solvent.]] | |||
| ], formerly dissolved in crystal of ], is left behind after the ] crystal of pyrite dissolved away. Note a corner of the former cube seen in center of rock.]] | |||
| The '''dissolution''' of gases, liquids, or solids into a liquid or other ] is a process by which these original states become solutes (dissolved components), forming a ] of the gas, liquid, or solid in the original solvent. ]s are the result of ''dissolution'' of one solid into another, and occur, e.g., in ]s, where their formation is governed and described by the relevant ].{{citation needed (lead)|date=June 2015}} In the case of a crystalline solid dissolving in a liquid, the crystalline structure must be disintegrated such that the separate atoms, ions, or molecules are released. For liquids and gases, the molecules must be able to form non-] ] with those of the solvent for a solution to form. | |||
| The ] of the overall, isolated process of dissolution must be negative for it to occur, where the component free energies contributing include those describing the disintegration of the associations holding the original solute components together, the original associations of the bulk solvent, and the old and new associations between the undissolved and dissolved materials.{{citation needed (lead)|date=June 2015}} | |||
| Dissolution is of fundamental importance in all chemical processes, natural and unnatural, from the decomposition of a dying organism and return of its chemical constituents into the ], to the laboratory testing of new, man-made soluble drugs, catalysts, etc.{{cn|date=June 2015}} Dissolution testing is widely used in industry, including in the pharmaceutical industry to prepare and ] chemical agents of consistent ] that will dissolve, optimally, in their target millieus as they were ]. | |||
| ==Dissolution by class of compound== | |||
| {{unreferenced section|date=June 2015}} | |||
| === Gases === | |||
| {{See also|Henry's law}} | |||
| Gaseous elements and compounds will dissolve in liquids dependent on the interaction of their bonds with the liquid solvent.{{dubious|date=June 2015}}{{cn|date=June 2015}} | |||
| === Liquids === | |||
| Gaseous elements and compounds may also dissolve in another liquid depending on the compatibility of the chemical and physical bonds in the substance with those of the solvent.{{dubious|date=June 2015}}{{cn|date=June 2015}} ]s play an important role in aqueous dissolution.{{cn|date=June 2015}} | |||
| === Ionic compounds === | |||
| For ]s, dissolution takes place when the ionic lattice breaks up and the separate ions are then solvated. This most commonly occurs in ]s, such as ] or ]: | |||
| :NaCl<sub>(s)</sub> → Na<sup>+</sup><sub>(aq)</sub> + Cl<sup>−</sup><sub>(aq)</sub> | |||
| In a colloidal dispersed system, small dispersed particles of the ionic lattice exist in equilibrium with the saturated solution of the ions, i.e. | |||
| :NaCl<sub>(aq)</sub> <math> \rightleftharpoons </math> Na<sup>+</sup><sub>(aq)</sub> + Cl<sup>−</sup><sub>(aq)</sub> | |||
| The ] of ionic salts in ] is generally determined by the degree of ] of the ions by water molecules. Such ]es occur by water donating spare ]s on the ] atom to the ion. The behavior of this system is characterised by the ]s of the components and the solubility product, defined as: | |||
| :<math>a_{Na^ + } \cdot a_{Cl^ - } = K_{sp}</math> | |||
| The ability of an ion to preferentially dissolve (as a result of unequal activities) is classified as the ]. This in turn results in the remaining particle possessing either a net positive/negative surface charge. | |||
| === Polar compounds === | |||
| Polar solid compounds can be amorphous or crystalline. Crystalline solids dissolve with breakdown of their crystal lattice, and due to their polarity, or non-polarity, mix with the ].{{dubious|date=June 2015}} | |||
| === Polymers === | |||
| The solubility of ] depends on the chemical bonds present in the backbone chain and their compatibility with those of the solvent.{{dubious|date=June 2015}} The ] is commonly used to evaluate polymer solubility. The closer the value of the parameters, the more likely dissolution will occur.{{vague|date=June 2015}} | |||
| == Rate of dissolution == | |||
| {{Cleanup|section|reason=that the sophistication of the content of this section, esp. the prose following the equation, relative to the rest of the article, makes it suspect with regard to its use of this single paywalled source|date=June 2015}} | |||
| The rate of dissolution quantifies the speed of the dissolution process. It depends on the chemical natures of the solvent and solute,{{vague|date=June 2015}} the temperature (and possibly to a small degree, the pressure), the degree of undersaturation,{{vague|date=June 2015}} the presence of a means of mixing during the dissolution, the interfacial surface area,{{vague|date=June 2015}} and the presence of "inhibitors" (e.g., substances adsorbed on the surface).{{vague|date=June 2015}}{{cn|date=June 2015}} | |||
| The rate can be often expressed by the ] or the Nernst and Brunner equation<ref>{{cite journal|first1=Aristides |last1=Dokoumetzidis |first2=Panos |last2=Macheras |date=2006|title=A century of dissolution research: From Noyes and Whitney to the Biopharmaceutics Classification System |journal=Int. J. Pharm. |volume=321|issue=1–2 |page=1–11 |DOI=10.1016/j.ijpharm.2006.07.011|url=http://www.sciencedirect.com/science/article/pii/S0378517306005813}}</ref> of the form: | |||
| :<math>\frac {dm} {dt} = A \frac {D} {d} (C_\rm{s}-C_\rm{b})</math> | |||
| where: | |||
| : ''m'' = mass of dissolved material | |||
| : ''t'' = time | |||
| : ''A'' = surface area of the interface between the dissolving substance and the solvent | |||
| : ''D'' = ] | |||
| : ''d'' = thickness of the boundary layer of the solvent at the surface of the dissolving substance | |||
| : ''C''<sub>s</sub> = mass concentration of the substance on the surface | |||
| : ''C''<sub>b</sub> = mass concentration of the substance in the bulk of the solvent | |||
| For dissolution limited by ], ''C''<sub>s</sub> 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<sup>2</sup>s and referred to as "intrinsic dissolution rate". The intrinsic dissolution rate is defined by the ]. | |||
| 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 the Noyes-Whitney equation. However, this is not a rule.{{says who?|date=June 2015}} | |||
| == See also == | |||
| ⚫ | |||
| *] | |||
| *] | |||
| *] | |||
| == References == | |||
| {{Reflist}} | |||
| ==Further reading== | |||
| {{Refbegin}} | |||
| *{{cite book|last1=Brady|first1=Patrick V.|first2=William A. |last2=House|chapter=4. Surface-controlled dissolution and growth of minerals|editor-last1=Brady|editor-first1=Patrick V.|title=Physics and chemistry of mineral surfaces|date=1996|publisher=CRC Press|location=Boca Raton, Fla.|isbn=9780849383519|pages=226–298}} | |||
| *{{cite book|editor-last1=Troy|editor-first1=David B.|editor-last2=Beringer|editor-first2=Paul|last1=Kumar|first1=Vijai|last2=Tewari|first2=Divya|chapter=Dissolution|title=Remington: The Science and Practice of Pharmacy|date=2006|publisher=Lippincott Williams & Wilkins|isbn=9780781746731|pages=672–690}} | |||
| *{{cite book|last1=Whitten|first1=Kenneth W.|title=Chemistry|date=2014|publisher=Brooks/Cole Cengage Learning|location=Belmont, CA|isbn=9781133610663|pages=506–514|edition=10th}} | |||
| {{Refend}} | |||
| {{Authority control}} | {{Authority control}} | ||
| ] | |||
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