Thermodynamics ntawm lub gaseous aggregate lub xeev ntawm teeb meem yog ib tug tseem ceeb ceg ntawm physics uas kawm thermodynamic equilibrium thiab quasi-static hloov nyob rau hauv lub systems. Cov qauv tseem ceeb ntawm qhov kev kwv yees ntawm tus cwj pwm ntawm cov tshuab yog raws li cov qauv roj zoo tagnrho. Nrog nws siv, qhov sib npaug ntawm Mendeleev-Clapeyron tau txais. Xav txog nws hauv kab lus.
Ideal gas
Raws li koj paub, tag nrho cov pa roj tiag tiag muaj cov molecules lossis atoms, qhov kev ncua deb ntawm qhov loj heev piv rau lawv qhov loj ntawm qhov tsis tshua muaj siab. Tsis tas li ntawd, nyob rau ntawm qhov kub thiab txias, ntawm qhov ntsuas qhov tseeb, lub zog kinetic ntawm cov molecules tshaj lawv lub zog muaj peev xwm cuam tshuam nrog kev cuam tshuam ntawm dipole-dipole tsis muaj zog (yog tias, ntxiv rau cov kev sib cuam tshuam no, muaj lwm hom tshuaj tiv thaiv, piv txwv li, ionic lossis hydrogen, ces lawv ua ib qho tseem ceeb pab rau lub peev xwm tivthaiv ntawm lub zog sab hauv system).
Nyob rauRau ntau cov pa roj tiag tiag nyob rau hauv cov xwm txheej ze li qub, ib tus tuaj yeem tsis quav ntsej lawv cov kev cuam tshuam sab hauv thiab qhov loj me me. Ob qhov kev kwv yees tseem ceeb no yog cov qauv roj zoo tagnrho.
Mendeleev's equation in physics
Nws yog qhov tseeb thiab ncaj ncees los hu qhov sib npaug no Clapeyron-Mendeleev txoj cai. Qhov tseeb yog tias nws tau sau thawj zaug los ntawm Fabkis tus engineer Emile Clapeyron xyoo 1834. Nws tau ua qhov no los ntawm kev txheeb xyuas cov kev cai roj ntawm Boyle-Mariotte, Gay-Lussac thiab Charles nrhiav tau los ntawm qhov pib ntawm lub xyoo pua 19th.
Qhov txiaj ntsig ntawm tus kws tshuaj Lavxias Lavxias Dmitry Mendeleev yog qhov tseeb tias nws tau muab qhov sib npaug ua lej niaj hnub thiab siv tau yooj yim. Tshwj xeeb, Mendeleev tau qhia rau hauv qhov sib npaug ntawm txhua qhov roj R=8, 314 J / (molK). Clapeyron nws tus kheej tau siv ntau qhov tsis xwm yeem uas ua rau cov txheej txheem suav nyuaj.
The Mendeleev-Clapeyron equation yog sau raws li nram no:
PV=nRT.
Qhov kev sib npaug no txhais tau hais tias cov khoom ntawm lub siab P thiab ntim V ntawm sab laug ntawm qhov kev qhia yog ib txwm proportional rau cov khoom ntawm qhov kub thiab txias T thiab tus nqi ntawm cov khoom n ntawm sab laug.
Cov lus qhia nyob rau hauv kev kawm tso cai rau koj kom tau txais kev cai lij choj roj yog tias koj kho ob ntawm nws plaub qhov kev txwv. Nyob rau hauv cov ntaub ntawv ntawm isoprocesses, kaw tshuab tau kawm nyob rau hauv uas tsis muaj kev sib pauv ntawm cov teeb meem nrog ib puag ncig (n=const). Cov txheej txheem no yog tus yam ntxwv los ntawm ib qho kev ntsuas kub tsis tu ncua (T, P lossis V).
Example problem
Tam sim no cia peb daws qhov teeb meem ntawm Mendeleev-Clapeyron kab zauv. Nws paub tias cov pa hnyav 500 grams yog nyob rau hauv ib lub tog raj kheej nrog lub ntim ntawm 100 litres ntawm lub siab ntawm 2 cua. Qhov ntsuas kub hauv lub zais pa yog dab tsi, vim tias lub kaw lus nyob hauv qhov ntsuas kub sib npaug.
Nco ntsoov tias, raws li lub ntsiab lus, tus nqi ntawm cov khoom raug xam los ntawm tus qauv:
n=m/M.
Qhov twg m yog qhov loj ntawm tag nrho cov khoom ntawm lub cev, M yog lawv qhov nruab nrab molar mass. Qhov kev sib npaug no tso cai rau peb rov sau dua qhov sib npaug ntawm Mendeleev hauv daim ntawv hauv qab no:
PV=mRT/M.
Qhov twg peb tau txais cov qauv ua haujlwm rau txoj haujlwm no:
T=PVM/(mR).
Nws tseem yuav hloov txhua qhov ntau rau SI units thiab hloov lawv mus rau hauv cov lus qhia no:
T=21013250, 10, 032/(0, 58, 314)=156 K.
Cuav kub yog -117 oC. Txawm hais tias cov pa ntawm qhov kub thiab txias no tseem gaseous (nws condenses ntawm -182.96 o C), nyob rau hauv cov xwm txheej zoo li no cov qauv roj tsuas yog siv tau kom tau txais kev kwv yees ntawm tus nqi suav.
