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| In [[chemical physics]] and [[physical chemistry]], '''chemical affinity''' is the electronic property by which dissimilar [[chemical species]] are capable of forming [[chemical compounds]].<ref>{{harvnb|Chisholm|1911|loc=Affinity, Chemical}}</ref> Chemical affinity can also refer to the tendency of an [[atom]] or compound to combine by [[chemical reaction]] with atoms or compounds of unlike composition.
| | Some users of computer or computer are aware which their computer become slower or have several errors after using for a while. But most folks don't know how to speed up their computer plus some of them don't dare to operate it. They always find several experts to keep the computer inside good condition nevertheless they have to invest some income on it. Actually, you are able to do it by oneself. There are many registry cleaner software that there are one of them online. Some of them are free plus we really should download them. After installing it, this registry cleaner software usually scan the registry. If it found these errors, it may report you and you can delete them to keep the registry clean. It is easy to work plus it is very the best method to repair registry.<br><br>Carry out window's system restore. It is extremely important to do this because it removes wrong changes that have taken place in the program. Some of the errors outcome from inability of your system to create restore point regularly.<br><br>Over time a disk can additionally receive fragmented. Fragmentation causes the computer to slow down because it takes windows much longer to locate a files location. Fortunately, the PC has a built inside disk defragmenter. You are able to run this system by clicking "Start" - "All Programs" - "Accessories" - "System Tools" - "Disk Defragmenter". You may today have the way to choose which drives or partition you need to defragment. This action could take you some time so it really is advised to do this regularly thus as to avoid further fragmentation plus to speed up a windows XP computer.<br><br>Check the Windows taskbar, that is on the lower appropriate hand corner of the computer screen. This taskbar comprise of programs we have running inside the background. If you have too numerous of them, they can steal the computer's resources.<br><br>Whenever it comes to software, this is the vital piece since it is the one running your system and different programs required inside a functions. Always keep the cleanliness of the system from obsolete data by getting a superior [http://bestregistrycleanerfix.com/registry-reviver registry reviver]. Protect it from a virus online by providing a workable virus protection program. You could have a monthly clean up by running the defragmenter system. This way it usually enhance the performance of the computer plus for you to avoid any mistakes. If you think something is wrong with all the computer software, plus we don't know how to fix it then refer to a technician.<br><br>Software mistakes or hardware mistakes which happen whenever running Windows and intermittent errors are the general reasons for a blue screen physical memory dump. New software or drivers that have been installed or changes inside the registry settings are the typical s/w causes. Intermittent mistakes refer to failed program memory/ hard disk or over heated processor and these too may result the blue screen physical memory dump error.<br><br>The 'registry' is simply the central database which shops all the settings plus choices. It's a actually important piece of the XP program, meaning which Windows is constantly adding plus updating the files inside it. The problems happen whenever Windows really corrupts & loses a few of these files. This makes your computer run slow, as it tries difficult to obtain them again.<br><br>If you desire to have a computer with fast running speed, you'd better install a advantageous registry cleaner to clean the useless files for you. As long as you take care of your computer, it might keep inside good condition. |
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| ==Modern conceptions==
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| In modern terms, we relate affinity to the phenomenon whereby certain atoms or molecules have the tendency to aggregate or bond. For example, in the 1919 book ''Chemistry of Human Life'' physician George W. Carey states that, "Health depends on a proper amount of iron phosphate Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> in the blood, for the molecules of this salt have chemical affinity for oxygen and carry it to all parts of the organism." In this antiquated context, chemical affinity is sometimes found synonymous with the term "magnetic attraction". Many writings, up until about 1925, also refer to a "law of chemical affinity".
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| [[Ilya Prigogine]] summarized the concept of affinity, saying, "All chemical reactions drive the system to a state of [[chemical equilibrium|equilibrium]] in which the ''affinities'' of the reactions vanish."
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| ==Thermodynamics==
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| The present [[IUPAC]] definition is that affinity ''A'' is the negative [[partial derivative]] of [[Gibbs free energy]] ''G'' with respect to [[extent of reaction]] ''ξ'' at constant [[pressure]] and [[temperature]].<ref>[http://www.IUPAC.org IUPAC Green Book and Gold Book in .pdf]</ref> That is,
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| :<math>A = -\left(\frac{\partial G}{\partial \xi}\right)_{P,T}.</math>
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| It follows that affinity is positive for [[Spontaneous process|spontaneous reactions]]. | |
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| In 1923, the Belgian mathematician and physicist [[Théophile de Donder]] derived a relation between affinity and the Gibbs free energy of a [[chemical reaction]]. Through a series of derivations, de Donder showed that if we consider a mixture of [[chemical species]] with the possibility of [[chemical reaction]], it can be proven that the following relation holds:
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| :<math> A = -\Delta_rG. \,</math>
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| With the writings of [[Théophile de Donder]] as precedent, [[Ilya Prigogine]] and Defay in ''Chemical Thermodynamics'' (1954) defined chemical affinity as the rate of change of the uncompensated [[heat]] of reaction ''Q''' as the [[Stoichiometry|reaction progress variable]] or reaction extent ''ξ'' grows infinitesimally:
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| :<math>A = \frac{{\mathrm d}Q'}{{\mathrm d}\xi}. \, </math>
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| This definition is useful for quantifying the factors responsible both for the state of equilibrium systems (where {{nowrap|1=''A'' = 0}}), and for changes of state of non-equilibrium systems (where ''A'' ≠ 0'').
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| == History ==
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| "Chemical affinity", historically, has referred to the "[[electromagnetic force|force]]" that causes [[chemical reaction]]s.<ref>[[Thomas Thomson (chemist)|Thomas Thomson]]. (1831). ''A System of Chemistry'', vol. 1. p.31 (chemical affinity is described as an "unknown force"). 7th ed., 2 vols.</ref> as well as, more generally, and earlier, the ″tendency to combine″ of any pair of substances. The broad definition, used generally throughout history, is that chemical affinity is that whereby substances enter into or resist decomposition.<ref name="Levere" >{{cite book | last = Levere | first = Trevor, H. | title = Affinity and Matter – Elements of Chemical Philosophy 1800-1865 | publisher = Gordon and Breach Science Publishers | year = 1971 | isbn = 2-88124-583-8}}</ref> | |
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| The term ''affinity'' has been used figuratively since c. 1600 in discussions of structural relationships in chemistry, [[philology]], etc., and reference to "natural attraction" is from 1616.
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| The idea of ''affinity'' is extremely old. Many attempts have been made at identifying its origins.<ref name="Levere" /> The majority of such attempts, however, except in a general manner, end in futility since "affinities" lie at the basis of all [[Magic (paranormal)|magic]], thereby pre-dating [[science]].<ref>Malthauf, R. P. (1966). The Origins of Chemistry. Pg. 299. London.</ref> [[Physical chemistry]], however, was one of the first branches of science to study and formulate a "theory of affinity". The name ''affinitas'' was first used in the sense of chemical relation by German philosopher [[Albertus Magnus]] near the year 1250. Later, those as [[Robert Boyle]], [[John Mayow]], [[Johann Glauber]], [[Isaac Newton]], and [[Georg Stahl]] put forward ideas on elective affinity in attempts to explain how [[heat]] is evolved during [[combustion reactions]].<ref>Partington, J.R. (1937). ''A Short History of Chemistry.'' New York: Dover Publications, Inc. ISBN 0-486-65977-1</ref>
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| The modern term chemical affinity is a somewhat modified variation of its eighteenth-century precursor "elective affinity" or elective attractions, a term that was used by the 18th century chemistry lecturer William Cullen.<ref>See Arthur Donovan, Philosophical Chemistry in the Scottish Enlightenment, Edinburgh, 1975</ref> Whether Cullen coined the phrase is not clear, but his usage seems to predate most others, although it rapidly became widespread across Europe, and was used in particular by the Swedish chemist [[Torbern Olof Bergman]] throughout his book ''De attractionibus electivis'' (1775). Affinity theories were used in one way or another by most chemists from around the middle of the 18th century into the 19th century to explain and organise the different combinations into which substances could enter and from which they could be retrieved.<ref>On the variety of affinity theories, see Georgette Taylor, Variations on a Theme; Patterns of Congruence and Divergence among 18th Century Affinity Theories, VDM Verlag Dr Muller Aktiengesellschaft, 2008</ref> [[Antoine Lavoisier]], in his famed 1789 ''[[Traité Élémentaire de Chimie]] (Elements of Chemistry)'', refers to Bergman’s work and discusses the concept of elective affinities or attractions.
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| According to chemistry historian Henry Leicester, the influential 1923 textbook ''Thermodynamics and the Free Energy of Chemical Reactions'' by [[Gilbert N. Lewis]] and [[Merle Randall]] led to the replacement of the term "affinity" by the term "[[thermodynamic free energy|free energy]]" in much of the English-speaking world.
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| According to Prigogine,<ref>I.Prigogine. (1980). ''From being to becoming. Time and Complexity in the Physical Sciences''. San Fracisco: W.H.Freeman and Co</ref> the term was introduced and developed by [[Théophile de Donder]].<ref>de Donder, T. (1936). ''L'affinité''. Ed. Pierre Van Rysselberghe. Paris: Gauthier-Villars</ref>
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| [[Goethe]] used the concept in his novel [[Elective Affinities]], (1809)
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| ===Geoffroy's 1718 affinity table===
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| The first-ever ''affinity table'', which was based on [[displacement reaction]]s, was published in 1718 by the French chemist [[Étienne François Geoffroy]]. Geoffroy's name is best known in connection with these tables of "affinities" (''tables des rapports''), which were first presented to the [[French Academy of Sciences]] in 1718 and 1720, as shown below: | |
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| <center> | |
| [[Image:Affinity-table.jpg|500px|center|thumb|Geoffroy's '''Affinity Table''' (1718): At the head of the column is a substance with which all the substances below can combine, where each column below the header is ranked by degrees of "'''affinity'''".]]
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| </center>
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| These were lists, prepared by collating observations on the actions of substances one upon another, showing the varying degrees of affinity exhibited by analogous bodies for different [[reagent]]s, and they retained their vogue for the rest of the century, until displaced by the profounder conceptions introduced by [[Claude Louis Berthollet|Claude Berthollet]].
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| == See also ==
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| *[[Chemistry]]
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| *[[Chemical reaction]]
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| *[[Chemical bond]]
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| *[[Electronegativity]]
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| *[[Electron affinity]]
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| *[[Étienne François Geoffroy]] — Geoffroy's 1718 Affinity Table
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| *[[Valency (chemistry)|Valency]]
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| *[[Affinity chromatography]]
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| *[[Affinity electrophoresis]]
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| ==Notes==
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| {{reflist}}
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| ==References==
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| *{{EB1911|wstitle=Affinity, Chemical}}
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| ==External links==
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| * [[William Whewell]]. [http://books.google.com/books?id=HGJxo1tmUP0C&lpg=PA15&ots=3Llmn3GJZr&dq=whewell%20%22chemical%20affinity%22&pg=PA15#v=onepage&q&f=false "Establishment and Development of the Idea of Chemical Affinity"]. ''History of Scientific Ideas''. 2:15ff.
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| *[http://nobelprize.org/nobel_prizes/chemistry/laureates/1920/press.html Chemical Affinity and Absolute Zero] - 1920 Nobel Prize in Chemistry Presentation Speech by [[Gerard de Geer]]
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| *[http://webcache.googleusercontent.com/search?q=cache:V8hWHBu0njMJ:eprints.dur.ac.uk/archive/00000085/01/Eddy_elements.rtf+Louis+Lemery&hl=en&ct=clnk&cd=10&gl=us Elements, Principles and the Narrative of Affinity] – Essay Review
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| [[Category:Physical chemistry]]
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Some users of computer or computer are aware which their computer become slower or have several errors after using for a while. But most folks don't know how to speed up their computer plus some of them don't dare to operate it. They always find several experts to keep the computer inside good condition nevertheless they have to invest some income on it. Actually, you are able to do it by oneself. There are many registry cleaner software that there are one of them online. Some of them are free plus we really should download them. After installing it, this registry cleaner software usually scan the registry. If it found these errors, it may report you and you can delete them to keep the registry clean. It is easy to work plus it is very the best method to repair registry.
Carry out window's system restore. It is extremely important to do this because it removes wrong changes that have taken place in the program. Some of the errors outcome from inability of your system to create restore point regularly.
Over time a disk can additionally receive fragmented. Fragmentation causes the computer to slow down because it takes windows much longer to locate a files location. Fortunately, the PC has a built inside disk defragmenter. You are able to run this system by clicking "Start" - "All Programs" - "Accessories" - "System Tools" - "Disk Defragmenter". You may today have the way to choose which drives or partition you need to defragment. This action could take you some time so it really is advised to do this regularly thus as to avoid further fragmentation plus to speed up a windows XP computer.
Check the Windows taskbar, that is on the lower appropriate hand corner of the computer screen. This taskbar comprise of programs we have running inside the background. If you have too numerous of them, they can steal the computer's resources.
Whenever it comes to software, this is the vital piece since it is the one running your system and different programs required inside a functions. Always keep the cleanliness of the system from obsolete data by getting a superior registry reviver. Protect it from a virus online by providing a workable virus protection program. You could have a monthly clean up by running the defragmenter system. This way it usually enhance the performance of the computer plus for you to avoid any mistakes. If you think something is wrong with all the computer software, plus we don't know how to fix it then refer to a technician.
Software mistakes or hardware mistakes which happen whenever running Windows and intermittent errors are the general reasons for a blue screen physical memory dump. New software or drivers that have been installed or changes inside the registry settings are the typical s/w causes. Intermittent mistakes refer to failed program memory/ hard disk or over heated processor and these too may result the blue screen physical memory dump error.
The 'registry' is simply the central database which shops all the settings plus choices. It's a actually important piece of the XP program, meaning which Windows is constantly adding plus updating the files inside it. The problems happen whenever Windows really corrupts & loses a few of these files. This makes your computer run slow, as it tries difficult to obtain them again.
If you desire to have a computer with fast running speed, you'd better install a advantageous registry cleaner to clean the useless files for you. As long as you take care of your computer, it might keep inside good condition.