Qhov sib txawv tseem ceeb ntawm qhov chaw melting thiab qhov chaw khov yog qhov melting point yog qhov kub ntawm cov khoom yuav mus rau cov kua hauv lub xeev qhov chaw khov yog qhov taw tes uas cov kua yuav hloov nws lub xeev mus rau ib qho khoom.
Cov kev hloov pauv yog cov txheej txheem uas muaj kev tso tawm hluav taws xob lossis lub zog nce. Melting point thiab freezing point yog cov ntsiab lus ntawm qhov kev hloov pauv tshwm sim. Nrog rau cov no, ntau lwm yam khoom ntawm cov khoom siv kuj tuaj yeem hloov pauv. Raws li kev xav, qhov chaw khov thiab qhov chaw melting ntawm cov khoom yog tib yam, tab sis qee zaum rau cov khoom siv, ob qhov tseem ceeb sib txawv ntawm ib leeg.
Lub ntsiab lus melting yog dab tsi?
Melting point yog qhov kub thiab txias uas cov khoom yuav hloov mus rau hauv nws lub xeev ua kua. Nws yog lub cev khoom peb tuaj yeem siv los txheeb xyuas qhov sib xyaw. Thaum cov khoom hloov mus rau hauv cov kua theem, ib theem hloov tshwm sim. Nws tshwm sim ntawm tus yam ntxwv kub rau lub siab muab. Rau qhov no, peb yuav tsum tau muab lub zog xav tau.
Cov theem hloov absorbs lub zog / cua sov (endothermic) thaum mus los ntawm cov khoom mus rau cov kua. Feem ntau, lub zog no tau muab rau hauv daim ntawv ntawm tshav kub. Thaum tshav kub kub yuav tsum tau nce qhov kub ntawm cov khoom mus rau nws lub xeev melting point. Tsis tas li ntawd, cov khoom xav tau lub zog kom yaj nws tus kheej. Peb hu lub zog cua sov ntawm fusion; Nov yog hom latent cua sov.
Cov cua sov tsis txaus yog cov cua sov uas tau nqus los yog tawm ntawm cov khoom thaum lub sij hawm hloov pauv. Cov kev hloov cua sov no tsis ua rau kub hloov pauv thaum lawv nqus los yog tso tawm. Yog li ntawd, thaum lub melting point, cov khoom absorbs tshav kub, tab sis qhov kub thiab txias yuav tsis hloov raws li. Thermodynamically, ntawm melting point, hloov Gibbs dawb zog yog xoom. Cov kab zauv nram qab no siv tau rau cov khoom ntawm qhov chaw melting. Nws qhia tau hais tias qhov kub thiab txias tsis hloov, tab sis enthalpy thiab entropy ntawm cov khoom hloov.
ΔS=ΔH/T
Vim tias cov tshuaj absorbs zog, enthalpy nce ntawm melting point. Nyob rau hauv lub xeev cov khoom, cov khoom yog zoo txiav txim thiab muaj tsawg zog. Tab sis nyob rau hauv lub xeev cov kua, lawv random xwm nce. Yog li ntawd, thaum lub melting point, entropy nce. Raws li qhov siab, muaj qhov tshwj xeeb melting point rau cov khoom muab. Peb tsuas tuaj yeem txiav txim siab cov ntsiab lus melting rau cov khib nyiab.
Daim duab 01: Melting Points of Different Chemical Elements
Hauv chav kuaj, peb tuaj yeem siv ntau cov tswv yim los txiav txim siab qhov melting point. Kev siv lub tshuab melting point yog yooj yim heev. Peb tuaj yeem muab qee cov hmoov ua hmoov nplej rau hauv ib lub capillary uas ib kawg yog kaw. Tom qab ntawd peb yuav tsum muab qhov kawg kaw uas muaj cov khoom rau hauv lub cuab yeej. Ntawm no, qhov kawg yuav tsum kov cov hlau sab hauv. Tom qab ntawd, peb tuaj yeem soj ntsuam cov khoom los ntawm lub qhov rais magnifying iav ntawm lub cuab yeej. Kuj tseem muaj lub ntsuas kub ntsuas ntsuas kub. Thaum kub maj mam nce, cov hlau yuav sov thiab, cov khoom nyob rau hauv capillary kuj yuav kub. Peb tuaj yeem soj ntsuam qhov taw tes uas lub melting pib thiab tiav. Thiab, qhov ntau ntawm no sib raug rau lub melting point. Lub melting point ntawm dej yog 0 ° C. Tungsten muaj qhov siab tshaj plaws melting point, uas yog 3410 ° C.
Dab tsi yog qhov taw qhia khov?
Qhov chaw khov yog qhov kub uas cov kua yuav hloov nws lub xeev mus rau qhov khoom. Qhov kub ntawm melting point thiab khov point rau ib yam khoom yog ntau dua los yog tsawg dua tus nqi. Piv txwv li, dej hloov mus rau hauv dej khov ntawm 0 ° C thiab nws qhov melting point kuj yog 0 ° C. Ntau qhov tseeb, qhov chaw khov kho piav qhia txog qhov hloov pauv ntawm theem ntawm cov teeb meem.
Daim duab 02: Dej khov dej khov
Ntxiv mus, cov txheej txheem ntawm kev khov cov tshuaj txo qis entropy. Muaj ib lo lus nyob rau hauv chemistry li "kev nyuaj siab qhov chaw khov kho" uas piav qhia tias qhov muaj cov kuab tshuaj tsis hloov pauv hauv cov tshuaj txo qhov txias txias ntawm cov kuab tshuaj.
Qhov txawv ntawm Melting Point thiab Qhov Ncauj Ncauj yog dab tsi?
Melting point thiab qhov khov khov yog cov lus qhia ntawm tib theem hloov. Qhov sib txawv tseem ceeb ntawm melting point thiab khov point yog qhov melting point yog qhov kub thiab txias ntawm cov khoom yuav mus rau lub xeev cov kua hos lub freezing point yog lub point uas tej kua yuav hloov nws lub xeev mus rau ib tug khoom. Ntxiv mus, kuj tseem muaj qhov sib txawv ntawm melting point thiab khov point nyob rau hauv cov nqe lus ntawm lawv entropy hloov; Thaum melting ib qho khoom, lub entropy nce, tab sis nyob rau hauv khov, lub entropy txo. Tsis tas li ntawd, txawm hais tias txoj kev xav, qhov chaw melting thiab qhov chaw txias txias yog qhov zoo sib xws rau cov khoom siv, qhov tseeb lawv txawv me ntsis.
Summary – Melting Point vs Freezing Point
Melting point thiab khov point yog ob lub cev ntawm cov khoom. Qhov sib txawv tseem ceeb ntawm melting point thiab qhov chaw khov yog qhov melting point yog qhov kub thiab txias ntawm cov khoom yuav mus rau lub xeev cov kua whereas khov point yog lub point uas tej kua yuav hloov nws lub xeev mus rau ib tug khoom.
