Charles's law

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Charles Law (also known as legal volume ) is an experimental gas law that describes how gas tends to expand when heated. The modern statements of Charles's law are:

When the pressure on the dry gas sample remains constant, the Kelvin temperature and volume will be directly related.

Hubungan proporsional langsung ini dapat ditulis sebagai:

${\ displaystyle V \ propto T}  ÂÂ$

atau

${\ displaystyle {\ frac {V} {T}} = k,} Â Â$

where:

V is the volume of gas,

T is the gas temperature (measured in kelvin),

k is a constant.

Undang-undang ini menjelaskan bagaimana gas mengembang ketika suhu meningkat; sebaliknya, penurunan suhu akan menyebabkan penurunan volume. Untuk membandingkan substansi yang sama di bawah dua set kondisi yang berbeda, hukum dapat ditulis sebagai:

${\ displaystyle {\ frac {V_ {1}} {T_ {1}}} = {\ frac {V_ {2}} {T_ {2}}} \ qquad {\ text {or}} \ qquad {\ frac {V_ {2}} {V_ {1}}} = {\ frac {T_ {2}} {T_ {1}}} \ qquad {\ text {or} } \ qquad V_ {1} T_ {2} = V_ {2} T_ {1}.}  ÂÂ$

The equation shows that, when the absolute temperature increases, the volume of the gas also increases proportionately.

Video Charles's law

Invention and legal naming

The law is named after scientist Jacques Charles, who formulated the original law in his unpublished work from the 1780s.

In two of the four essay series presented between 2 and 30 October 1801, John Dalton showed by experiment that all the gases and vapors he studied expanded by an equal amount between two fixed points of temperature. The French natural philosopher Joseph Louis Gay-Lussac confirmed the discovery in a presentation to the French National Institute on January 31, 1802, although he recognized the discovery to an unpublished work of the 1780s by Jacques Charles. The basic principles have been described by Guillaume Amontons and Francis Hauksbee a century earlier.

Dalton is the first to show that the law applies generally to all gases, and steam volatile liquids if temperatures well above the boiling point. Gay-Lussac agrees. By measuring only at two fixed points of water thermometric, Gay-Lussac can not show that the equations connecting volume with temperature are linear functions. On a mere mathematical basis, the Gay-Lussac paper does not allow the assignment of a law expressing a linear relationship. Dalton and Gay-Lussac's main conclusions can be expressed mathematically as:

$Â\; Â{\displaystyle Â\; Â\; Â\; Â\; Â\; Â\; Â}$ _{         V                      100                          -                 V                ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,                          =          k                 V                ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,                                        {\ displaystyle V_ {100} -V_ {0} = kV_ {0} \,}  Â}

where V ₁₀₀ is the volume occupied by the gas sample provided at 100 ° C; V ₀ is the volume occupied by the same gas sample at 0 Â ° C; and k are the same constants for all gases at constant pressure. This equation contains no temperature and has nothing to do with what is known as Charles's Law. The Gay-Lussac value for k ( / _2,6666 ), is identical to Dalton's previous value for steam and amazingly close to the current value of ¹ / _2,7315 . Gay-Lussac credits this equation for unpublished remarks by Republican J. Charles in 1787. In the absence of a strong record, the gas law relating to volume to temperature can not be named according to Charles. Dalton measurements have more scope about temperature than Gay-Lussac, not only measuring volume at fixed points of water, but also at two midpoints. Unaware of the inaccuracies of mercury thermometers at the time, which were divided into equal parts between fixed points, Dalton, after concluding in Essay II that in the case of vapors, "each elastic fluid expands almost uniformly to 1370 or 1380 parts by 180 degrees ( Fahrenheit) heat ", can not confirm for gas.

Maps Charles's law

Relation to absolute zero

Charles's law seems to imply that the volume of gas will drop to zero at a certain temperature (-266.66 ° C according to the Gay-Lussac figure) or -273.15 ° C. Gay-Lussac is clear in its description that the law does not apply to temperatures low:

but I can mention that this latter conclusion can not be true except as long as the compressed vapor remains fully in the elastic state; and this demands that their temperature should be high enough to allow them to withstand the pressure that tends to make them consider the liquid state.

At absolute zero temperature, the gas has zero energy and hence the molecule limits the motion. Gay-Lussac had no experience of liquid air (first prepared in 1877), though he seems to believe (as Dalton did) that "permanent gases" such as air and hydrogen can be melted. Gay-Lussac also works with steam volatile fluid in demonstrating Charles's laws, and is aware that the law does not apply just above the boiling point of the liquid:

However I can comment that when the ether temperature is just slightly above its boiling point, the condensation is slightly faster than the atmospheric air. This fact is linked to a phenomenon that is shown by so many bodies when moving from liquid to solid state, but that no longer makes sense at the temperature some degree above where the transition takes place.

The first mention of temperatures in which the volume of gas may drop to zero is by William Thomson (later known as Lord Kelvin) in 1848:

This is what we can anticipate, when we reflect that unlimited cold must correspond to a limited number of degrees of air thermometer below zero; because if we push the strict passing principle, stated above, far enough, we must arrive at a point corresponding to the volume of air reduced to none, which will be marked as -273 Â ° of scale (-100/.366 , if.366 becomes the expansion coefficient); and therefore -273 Â ° of an air thermometer is a point that can not be achieved at finite but low temperatures.

However, the "absolute zero" on the Kelvin temperature scale was originally defined in terms of the second law of thermodynamics, which Thomson himself described in 1852. Thomson does not consider that this equals "the zero volume point" of Charles 'law, only that Charles' minimums that can be achieved. Both can be shown to be equivalent to Ludwig Boltzmann's statistical view of entropy (1870).

Namun, Charles Juga Menyatakan:

Volume massa tetap dari gas kering meningkat atau menurun sebesar ¹ / ₂₇₃ kali volume pada 0 Ã, ° C untuk setiap kenaikan 1 ° C atau penurunan suhu. Jadi:

${\ displaystyle V_ {T} = V_ {0} ({\ tfrac {1} {273}} ​​â € <â € <\ kali V_ {0 }) \ kali T} Â Â$

${\ displaystyle V_ {T} = V_ {0} (1 {\ tfrac {T} {273}})} Â Â$

di mana V _T adalah volume gas pada suhu T , V ₀ adalah volume by 0 Ã, ° C.

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Hubungan dengan teori kinetik

The kinetic theory of gases connects the macroscopic properties of gases, such as pressure and volume, to the microscopic nature of molecules that make up gases, especially the mass and velocity of molecules. To obtain Charles's laws of kinetic theory, it is necessary to have a microscopic temperature definition: this can be easily taken as a temperature proportional to the average kinetic energy of a gas molecule, sub> k :

${\ displaystyle T \ propto {\ bar {E_ {rm {k}}}}. \,}$

Berdasarkan has defined her, showed a hook Charles hampir tidak berarti. Theory kinetik yang setara dengan hukum gas ideal menghubungkan PV denote energi kinetik rata-rata:

${\ displaystyle PV = {\ frac {2} {3}} N {\ bar {E _ {\ rm {k}}}} \,} Â Â$

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Lihat juga

• Hukum Boyle
• Hukum gas gabgangan
• Hukum Gay-Lussac
• Hukum Avogadro
• Hukum gas ideal
• Tangan ketel

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Reference

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Bacaan lebih lanjut

• KrÃÆ'¶nig, A. (1856), "GrundzÃÆ'¼ge einer Theorie der Gase", Annalen der Physik , 99 : 315-22, Bibcode: 1856AnP... 175..315K, doi: 10.1002/andp.18561751008 . Faksimili di BibliothÃÆ'¨que nationale de France (pp.Ã, 315-22).
• Clausius, R. (1857), "Ueber die Art der Bewegung, welche wir WÃÆ'¤rme nennen", Annalen der Physik und Chemie , 176 : 353-79, Bibcode: 1857AnP... 176..353C, doi: 10.1002/andp.18571760302 . Faksimili di BibliothÃÆ'¨que nationale de France (pp.Ã, 353-79).
• Joseph Louis Gay-Lussac - Liste de ses communications , diarsipkan dari aslinya por 23 Oktober 2005 . (dalam bahasa Prancis)

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Tautan eksternal

• Simulasi hukum Charles dari Davidson College, Davidson, North Carolina
• Demonstrasi hukum Charles oleh Prof. Robert Burk, Carleton University, Ottawa, Canada
• Animasi hukum Charles dari Proyek Leonardo (GTEP/CCHS, UK)
• Calculator Hukum Charles dari EngineeringUnits.com, AS, Inggris)

Source of the article : Wikipedia