Van der Walls sunan wani masanin kimiyyar lissafi ɗan ƙasar Holland ne, JD van der Waals (1837-1923). Daidaiton Jihar Van der Waals lissafi ne na yanayin iskar gas, kama da daidaiton yanayin iskar gas mai kyau. Bambancin shine, Daidaiton yanayin iskar gas mai kyau ba zai iya samar da sakamako mai kyau ba idan matsin lamba da yawan iskar gas na gaske sun isa. Yayin da Daidaiton Jihar Van der Waals zai iya samar da sakamako mafi daidaito.
Kasancewar wannan lissafin ya samo asali ne daga Van der Waals, wanda ya fahimci iyakokin lissafin yanayin da ya dace. Waals, suna gyara lissafin yanayin da ya dace da iskar gas, ta hanyar ƙara abubuwa da yawa waɗanda suma ke tasiri ga yanayin iskar gas na gaske, lokacin da matsin lamba da yawan iskar gas na gaske suka yi yawa.
Matsin iskar gas yana da daidaiton juzu'i da girma. Idan matsin iskar gas ya ƙaru, ƙarfin iskar gas yana raguwa. Akasin haka, idan ƙarfin iskar gas ya ragu, matsin iskar gas yana ƙaruwa. Lokacin da ƙarfin iskar gas ya ragu, yawan iskar gas yana ƙaruwa (yawa = taro / girma). Ana iya cewa matsin yana da daidaiton juzu'i kai tsaye da yawa. Idan matsin iskar gas ya yi girma, yawan iskar gas ma yana da girma. Akasin haka, idan matsin iskar gas ya ƙaru, yawan iskar gas ma ƙarami ne. Matsin iskar gas ma yana da daidaiton juzu'i kai tsaye da zafin jiki. Idan matsin iskar gas ya ƙaru, zafin iskar gas yana ƙaruwa. Za mu iya kammala cewa idan matsin iskar gas ya ƙaru, zafin iskar gas da yawa, yayin da ƙarfin iskar gas ke raguwa.
Idan yawan iskar gas ya ragu, tazarar da ke tsakanin kwayoyin halitta tana ƙara kusantowa. Idan tazarar da ke tsakanin kwayoyin halitta ta ƙara kusantowa, kwayoyin halitta suna jan hankalin juna. Kamar lokacin da aka kawo wani ƙarfe kusa da maganadisu. Idan tazarar da ke tsakanin maganadisu da ƙarfe ta isa sosai, maganadisu ba zai iya jan ƙarfe ba. Amma idan tazarar da ke tsakanin maganadisu da ƙarfe ta kusa, ƙarfen yana kusantowa. Lokacin da kwayoyin halitta suka kusa karo, electrons ɗin da ke wajen kwayar halitta suna korar juna (korar lantarki). Sakamakon haka, kwayoyin halitta ba za su iya mannewa tare ba. Daga wannan ɗan gajeren bayanin, za a iya cewa ƙarfin jan ƙarfe tsakanin kwayoyin halitta yana shafar yanayin iskar gas.
Idan matsin iskar gas ya yi yawa, kuma girman iskar gas ya yi ƙanƙanta, tazarar da ke tsakanin ƙwayoyin halitta tana kusantowa. Saboda ƙwayoyin halitta suna da girma (diamita na atomic = 10 -10 m), to muna buƙatar la'akari da girman waɗannan ƙwayoyin.
Van der Waals yana rage lissafin yanayi, idan aka yi la'akari da yawan kwayoyin halitta da kuma hulɗar da ke faruwa tsakanin kwayoyin halitta. Lissafin da Van der Waals ya samo asali ne sakamakon gyaran daidaiton yanayin iskar gas mai kyau PV = n R T. Daidaiton Jiha na Van der Waals:
P = matsin lamba na iskar gas (N / m 2 = Pa)
V = girman iskar gas ( m3 )
R = daidaitaccen iskar gas na duniya (R = 8.315 J / mol. K = 8315 kJ / kmol. K)
T = zafin jiki (K)
a = ma'aunin gwaji (ƙimar ta dogara ne akan ƙarfin jan hankali tsakanin ƙwayoyin iskar gas)
b = ma'aunin gwaji (wanda ke wakiltar girman kwayar halitta ɗaya ta ƙwayoyin iskar gas)
n = Adadin moles (mol)
bn = jimlar adadin ƙwayoyin iskar gas
Ana samun daidaiton a da b ta hanyar gwaje-gwaje. Ƙimar da ta dace a da b ta dogara ne akan nau'in iskar gas.
n2 /V2 = rabon kwata na adadin moles (n) tare da murabba'in girman gas (V). Ƙimar n2 /V2 ya dogara da matsin lamba da yawan iskar gas. Idan matsin iskar gas (P) ya yi yawa, to girman iskar gas (V) ƙarami ne. Ƙaramin V, mafi girma shine n2 /V2Idan yawan iskar gas ɗin ya yi ƙanƙanta (n2 /V2 babba ne) nisan da ke tsakanin kwayoyin halitta ya fi kusa. Yayin da nisan da ke tsakanin kwayoyin halitta yake kusa, haka nan hulɗar da ke tsakanin waɗannan kwayoyin halitta (tana karo, tana jawo juna). Saboda haka, n2 /V2 daidai gwargwado ne kai tsaye da daidaito (idan aka kwatanta da lissafin van der Waals). Mafi girman ƙimar n2 /V2, mafi girman jan hankali tsakanin kwayoyin halitta (a).
Akasin haka, idan matsin iskar gas (P) ƙanana ne, to ƙarar iskar gas (V) za ta yi girma. Mafi girman V, ƙaramar n za ta yi girma.2 /V2Ƙasan n2 /V2, ƙarancin ƙarfin jan hankali tsakanin ƙwayoyin halitta.
(V – bn) = Bambanci tsakanin yawan iskar gas da jimlar yawan ƙwayoyin iskar gas. Madaidaici b yana wakiltar adadin mole ɗaya na ƙwayoyin iskar gas. n = adadin mole. Samfurin lokacin da ke tsakanin b da n (bn) = jimlar yawan ƙwayoyin iskar gas. Idan matsin iskar gas (P) ya ƙara girma, to girman iskar gas (V) zai ragu.
Ƙaramin V, ƙarami (V – bn). Wannan yana nufin cewa nisan da ke tsakanin kwayoyin halitta yana ƙaruwa kuma, ba shakka, jan hankali tsakanin kwayoyin halitta yana ƙaruwa. Akasin haka, idan matsin iskar gas ya ragu, ƙarar iskar gas ɗin yana ƙaruwa. Girman iskar gas mai mahimmanci, mafi girma (V – bn). Mafi girma (V – bn), mafi ƙanƙantar jan hankali tsakanin ƙwayoyin iskar gas.
Za mu iya cewa lissafin yanayin van der Waals yana bayyana ainihin yanayin iskar gas daidai fiye da daidaitaccen lissafin iskar gas. Idan matsin lamba da yawan iskar gas sun isa girma, lissafin van der Waals yana ba da sakamako mafi daidaito. Idan matsin iskar gas bai yi yawa ba, to za a iya yin watsi da ( 2 / V 2 ) da (V-bn), don haka lissafin yanayin Van der Waals ya canza zuwa daidaitaccen lissafin yanayin iskar gas.
