Thermal los thiab lub enthalpy ntawm tsim. Introduction to thermochemistry

Enthalpy ntawm tsim, thermodynamic cuab yeej raws li ib qho tseem ceeb tshuaj, uas qhia tus nqi ntawm lub zog uas yog nyob rau hauv nws cov molecular qauv yuav tsum hloov dua siab tshiab rau hauv tshav kub, yog ib qhov tseem ceeb cov ntsiab thermodynamic Science News for KIDS. Qhov no ceg ntawm science tau kawm qhov kub thiab txias yam ntxwv sib txawv ntawm cov tshuaj thiab lawv yuav tsum vam rau tag nrho cov hom ntawm lub cev thiab tshuaj tsis, Thaum tshav kub kub muaj peev xwm thiab theem zaus. Tsim enthalpy (los ntawm Greek "entalpio." - "rhuab pem") thiab txiav txim seb cov tshuaj tebchaw yuav tsum tau npaum li cas ntawm lub zog los tsim ib tug complex tshuaj los ntawm tej yam yooj yim hais, coj raws li ib tug txoj cai, nyob rau hauv nws cov feem ntau ruaj khov lub xeev.

Piv txwv li, hydrogen, nitrogen los yog cov pa xws li yog gaseous daim ntawv no, cov pa roj carbon - carbon thiab bromine - kua hauv lub xeev. Enthalpy ntawm tsim - ib tug tseem ceeb heev thermochemical zog, raws li nws enables tsis tsuas mus rau ntse kom daws tau qhov teeb meem raws, tab sis kuj tsim ib tug ntau yam ntawm tshuaj technologies thiab tsim tus tsim nyog cov khoom mus nqa lawv tawm. Thiab qhov no yog tau tsuas yog hais tias muaj yog muaj tseeb thiab ncav raws li cov lus qhia nyob rau hauv physicochemical thiab thermodynamic thaj chaw ntawm ntau yam sib txuas. Cov ntaub ntawv no feem ntau roos ntau tshaj li tsib caug feem pua ntawm cov thawj cov ntaub ntawv rau tus tsim ntawm complex cov khoom rau kev thwmsim los yog muaj lub hom phiaj.

Yog li ntawd, txoj kev tshawb ntawm cov khoom ntawm ntau yam tshuaj, xws li cov enthalpy ntawm tsim, yog hnub no ib tug ntawm cov tseem ceeb thermochemistry uas feem ntau siv thermodynamic cov tshuaj tiv thaiv sib npaug los mus txiav txim cov nqi no. Lawv yuav tsum qhia cov sau ua ib pawg xeev ntawm lub substance, thiab lub cua sov cov nyhuv yog ntshai raws li ib tug ntawm cov tshuaj tiv thaiv cov khoom.

Lub tshav kub ntawm cov tshuaj tiv thaiv, xws li tsim enthalpy ntawm lub yam khoom uas yog txiav txim siab siv txhua yam calorimeters. Lub thiaj li hu ua lub foob pob calorimeter yog ib tug zoo-thermostatted txog ntsha kaw yam nyob rau hauv uas thermal zog tso raws li ib tug tshwm sim ntawm ib yam tshuaj cov tshuaj tiv thaiv yog noj xwb yuav ua tau kom qhov kub thiab txias nyob rau hauv lub sab hauv qhov chaw. Lub calorimeter yog reactive tshuaj thiab cov tshuaj tiv thaiv pib los ntawm nws tus kheej nyob rau hauv ntau txoj kev. Tom qab ntawd, puab kub ntawm qhov nruab nrab yog ntsuas los ntawm ib tug pas ntsuas kub los yog thermocouple.

Nyob rau hauv no txoj kev, ntsuas los ntawm tus txheej txheem enthalpy ntawm tsim ntawm ntau txhiab ntawm tshuaj. Tag nrho cov ntaub ntawv kom zoo thiab meticulously kaw nyob rau hauv ib tug tshwj xeeb neeg ua tim khawv thiab cov ntxhuav. Tsis tas li ntawd, lub enthalpies ntawm tsim tsis sib txawv ntawm cov tshuaj yuav tsum xam lej siv zoo xws li cov ntau ntawm cov reacting tshuaj thiab cov tshuaj tiv thaiv cov khoom no. Rau qhov no thiab siv cov aforementioned thermodynamic sib npaug.

Tej yam yooj yim tshuaj yog yuav luag ib txwm tsim enthalpy yog sib npaug zos rau zero. Yuav ua li cas yog tseem coj mus rau hauv tus account nyob rau hauv cov lus teb. Thiab qhov no thermodynamic vaj tse, rau piv txwv, phosphorus trichloride yuav xam siv cov nram qab no mis:

P (tv.) + 1½ C ₃ = RS (x).

Rau gaseous co (Fe, AL) lub enthalpy ntawm tsim yog txawv los ntawm xoom thiab nruab nrab yog cov thermochemical transformation ntawm txoj kev hloov los ntawm lub khoom hauv lub xeev (tus qauv) nyob rau hauv lub gaseous lub xeev. Qhov no tus nqi yog ntaus nqi raws li lub enthalpy ntawm vaporization, kuj hu ua atomization.