Kub thiab kev hloov pauv ntawm theem - teeb meem thiab kev daws teeb meem

1. Raws li daim duab kos, dej 5-kg nqus cua sov li cas thaum lub sijhawm ua CD? Cua sov tshwj xeeb ntawm dej = 4,200 J/kg ^o C.

Paub: Kub thiab kev hloov pauv ntawm theem - teeb meem thiab kev daws teeb meem 1

Qhov hnyav (m) = 5 kg

Cov cua sov tshwj xeeb ntawm dej (c) = 4200 J/kg ^o C

Kub pib (T1 ₎ = 0 ^o C

Qhov kub kawg (T2 ₎ = 10 ^o C

Qhov kev hloov pauv ntawm qhov kub thiab txias (ΔT) = 10 ^o C – 0 ^o C = 10 ^o C

Xav tau: Kub (Q)

Tshuaj:

Q = mc ΔT = (5 kg)(4200 J/kg ^o C)(10 ^o C) = (5)(4200 J)(10) = (50)(4200 J) = 210,000 Joules

^{2. Yog tias qhov kub tshwj xeeb ntawm dej khov yog 2100 J/kg o} C thiab qhov kub ntawm kev sib xyaw rau dej khov yog 336,000 J/kg, qhov kub uas 20 grams ntawm dej khov nqus tau yog dab tsi thaum lub sijhawm AC.

Kub thiab kev hloov pauv ntawm theem - teeb meem thiab kev daws teeb meem 2 Paub:

Qhov hnyav ntawm dej khov (m) = 200 grams = 200/1000 kilograms = 0.2 kilograms

Cov cua sov tshwj xeeb (c) = 2100 J/kg ^o C

Kub ntawm kev sib xyaw rau dej khov (L₂F ₎ = 336,000 J/kg

Xav tau: Kub uas dej khov nqus thaum lub sijhawm AC ua haujlwm

Tshuaj:

Thaum lub sijhawm ua AB, dej khov nqus cua sov kom hloov nws qhov kub ntawm -10 ^o C mus rau 0 ^o C.

Q = mc ΔT

Q = cua sov, m = qhov hnyav ntawm dej khov, c = cua sov tshwj xeeb ntawm dej khov, ΔT = qhov hloov pauv ntawm qhov kub thiab txias

Q ₁ = mc ΔT = (0.2)(2100)(0-(-10) = (0.2)(2100)(10) = (2)(2100) = 4200 Joules

Thaum lub sijhawm ua BC, cua sov raug nqus kom yaj tag nrho cov dej khov mus ua dej. Hauv cov txheej txheem no tsuas yog hloov pauv theem thiab tsis muaj kev hloov pauv ntawm qhov kub thiab txias. Qhov kub ntawm dej khov thiab dej tseem nyob 0 ^o C.

Kub nqus thaum lub sijhawm ua haujlwm BC:

Q ₂ = m L _F = (0.2 kg)(336,000 J/kg) = 67,200 Joules

Kub nqus thaum lub sijhawm AC txheej txheem:

Q = Q ₁ + Q ₂ = 4200 Joules + 67,200 Joules = 71,400 Joules

3. Ib tug dej 2-kg raug cua sov, thiab cua sov ntawm kev ua pa rau dej = 2.27 x 106 ^J /kg, cua sov tshwj xeeb rau dej = 4,200 J/kg ^o C thiab lub siab atmospheric yog 1 atm, qhov cua sov uas dej nqus tau thaum lub sijhawm ua BC yog dab tsi?

Paub: Kub thiab kev hloov pauv ntawm theem - teeb meem thiab kev daws teeb meem 3

Qhov hnyav (m) = 2 kg

Lub zog cua sov ntawm dej ua pa (LV ₎ = 2.27 x 106 ^J /kg

Cov cua sov tshwj xeeb rau dej (c) = 4,200 J/kg ^o C

Xav tau: Kub nqus thaum lub sijhawm ua haujlwm BC.

Tshuaj:

Hauv cov txheej txheem AB, cua sov raug nqus kom ua rau qhov kub ntawm dej nce ntxiv ntawm 60 ^o C mus rau 100 ^o C.

Q = m L _V = (2 kg)(2.27 x 106 ^J /kg) = 4.54 x 106 ^Joules = 4540 x 103 ^Joules = 4540 kilo Joules

4. Raws li daim duab hauv qab no, yog tias qhov hnyav ntawm dej khov yog 500 grams, qhov kub tshwj xeeb yog 2100 J/kg ^o C thiab qhov kub latent ntawm kev sib xyaw ntawm dej khov yog 336,000 J/kg. Txheeb xyuas qhov kub uas xav tau hauv cov txheej txheem P-Q-R.

Paub: Kub thiab kev hloov pauv ntawm theem - teeb meem thiab kev daws teeb meem 5

Qhov hnyav ntawm dej khov (m) = 500 grams = 500/1000 kg = 0.5 kg

Cov cua sov tshwj xeeb rau dej khov (c) = 2100 J/kg ^o C

Latent cua sov ntawm fusion (L₂F ₎ = 336,000 J / kg

Xav tau: Kub

Tshuaj:

Txheej Txheem PQ = cua sov nqus tau los ua kom qhov kub ntawm dej khov nce ntawm -4 ^o C mus rau 0 ^o C

Txheej Txheem QR = cua sov uas dej khov nqus tau los yaj tag nrho cov dej khov rau hauv dej

Kub uas nqus tau thaum lub sijhawm ua haujlwm PQ suav los ntawm kev siv kab zauv:

Q = mc ΔT

Q = cua sov, m = pawg, c = cua sov tshwj xeeb ntawm dej khov, ΔT = kev hloov pauv ntawm qhov kub thiab txias

Cov dej khov uas nqus cua sov thaum lub sijhawm ua haujlwm PQ suav los ntawm kev siv cov qauv no:

Q = (0.5 kg)(2100 J/kg ^o C)(0 ^o C-(-4 ^o C))

Q = (0.5 kg)(2100 J/kg ^o C)(0 ^o C + 4 ^o C)

Q = (0.5 kg) (2100 J / kg ^o C) (4 ^o C)

Q = (0.5)(2100 J)(4)

Q = 4200 Joules

Kub uas nqus tau thaum lub sijhawm ua haujlwm QR xam los ntawm kev siv cov qauv no:

Q = m L _F

Q = (0.5 kg) (336,000 J/kg)

Q = (0.5)(336,000 J)

Q = 168,000 Joules

Tag nrho cov cua sov:

Q = 4200 Joules + 168,000 Joules

Q = 172,200 Joules

Q = 172.2 kilo Joule

Q = 172.2 kJ

5. Cov dej khov uas muaj qhov hnyav 50 grams raug cua sov los ntawm -5 ^o C mus rau hauv dej ntawm 60 ^o C. Yog tias qhov kub ntawm kev sib xyaw rau dej khov yog 80 cal/gram, qhov kub tshwj xeeb rau dej khov yog 0.5 cal/gram ^o C, qhov kub tshwj xeeb rau dej yog 1 cal/gram ^o C, txiav txim siab qhov kub uas xav tau hauv cov txheej txheem CD.

Paub:

Qhov hnyav ntawm dej khov = qhov hnyav ntawm dej (m) = 50 grams Kub thiab kev hloov pauv ntawm theem - teeb meem thiab kev daws teeb meem 6

Lub cua sov latent ntawm kev sib xyaw rau dej khov (L₂F ₎ = 80 calories / gram

Qhov kub tshwj xeeb rau dej khov (c dej khov) = 0.5 cal/gram ^o C

Cov cua sov tshwj xeeb rau dej (c dej) = 1 cal/gram ^o C

Xav tau: Kub xav tau hauv cov txheej txheem CD

Tshuaj:

Hauv cov txheej txheem A mus rau B, cua sov yog siv los ua kom qhov kub ntawm dej khov nce ntawm -5 ^o C mus rau 0 ^o C. Cua sov yog xam siv cov qauv no: Q = mc ΔT, qhov twg Q = cua sov, m = qhov hnyav ntawm dej khov, c = cua sov tshwj xeeb rau dej khov, ΔT = qhov hloov pauv ntawm qhov kub ntawm -5 ^o C mus rau 0 ^o C.

Hauv cov txheej txheem B txog C, cua sov siv los yaj tag nrho cov dej khov ua dej. Hauv cov txheej txheem no, qhov kub tsis hloov pauv. Cua sov xam siv cov qauv no: Q = m L _F , qhov twg Q = cua sov, m = qhov hnyav ntawm dej khov, L _F = cua sov latent ntawm kev sib xyaw ntawm dej khov.

Hauv cov txheej txheem C mus rau D, cua sov yog siv los tsa qhov kub ntawm dej ntawm 0 ^o C mus rau 60 ^o C. Cua sov yog xam siv cov qauv no: Q = mc ΔT, qhov twg Q = cua sov, m = qhov hnyav ntawm dej, c = cua sov tshwj xeeb ntawm dej, ΔT = qhov hloov pauv ntawm qhov kub ntawm 0 ^o C mus rau 60 ^o C.

Lub cua sov xav tau los ntawm txheej txheem C mus rau D:

Q = mc ΔT = (50 gram)(1 cal/gram ^o C)(60 ^o C-0 ^o C) = (50)(1)(60) cal = 3000 cal

6. Yog tias qhov hnyav ntawm dej khov yog 1 kg, qhov kub tshwj xeeb ntawm dej khov yog 2100 J/kg ^o C, qhov kub latent ntawm kev sib xyaw rau dej khov yog 336,000 J/kg thiab qhov kub tshwj xeeb ntawm dej yog 4200 J/kg ^o C, ces txiav txim siab qhov kub uas xav tau hauv cov txheej txheem PQR.

Paub:

Qhov hnyav ntawm dej khov = 1 kg Kub thiab kev hloov pauv ntawm theem - teeb meem thiab kev daws teeb meem 7

Latent cua sov ntawm fusion ntawm dej khov (L₂F ₎ = 336,000 J / kg

Qhov kub tshwj xeeb ntawm dej khov (c dej khov) = 2,100 J/kg ^o C

Cov cua sov tshwj xeeb ntawm dej (c dej) = 4,200 J/kg ^o C

Xav tau: Kub xav tau hauv cov txheej txheem PQR

Tshuaj:

Hauv cov txheej txheem P txog Q, cua sov siv los ua kom qhov kub ntawm dej khov nce ntawm -5 ^o C mus rau 0 ^o C. Cua sov raug suav los ntawm kev siv cov qauv no: Q = mc ΔT, qhov twg Q = cua sov , m = qhov hnyav ntawm dej khov , c = cua sov tshwj xeeb ntawm dej khov, ΔT = qhov hloov pauv ntawm qhov kub ntawm -5 ^o C mus rau 0 ^o C.

Kub xav tau nyob rau hauv cov txheej txheem P rau Q:

Q = mc ΔT = (1)(2100)(0-(-5)) = (2100)(5) = 10500 Joules

Hauv cov txheej txheem Q txog R, qhov kub uas xav tau los yaj tag nrho cov dej khov rau hauv dej. Hauv cov txheej txheem no, qhov kub tsis hloov pauv. Qhov kub xam siv cov qauv no: Q = m L _F , qhov twg Q = cua sov , m = qhov loj ntawm dej khov , L _F = cua sov latent ntawm kev sib xyaw ntawm dej khov.

Kub xav tau nyob rau hauv cov txheej txheem Q rau R:

Q = m L _F = (1)(336,000) = 336,000 Joules

Tag nrho cov cua sov:

10,500 + 336,000 = 346,500 Joules

Kub latent yog dab tsi?
- tebKub latent yog lub zog kub uas xav tau los hloov theem ntawm ib yam khoom yam tsis hloov nws qhov kub. Nws sawv cev rau lub zog uas xav tau los rhuav lossis tsim cov kev sib txuas ntawm cov molecular thaum lub sijhawm hloov theem.
Vim li cas qhov kub thiab txias thiaj li tsis hloov pauv thaum lub sijhawm hloov pauv theem?
- tebThaum lub sijhawm hloov pauv theem, tag nrho cov zog cua sov uas muab los yog tshem tawm yog siv los hloov theem ntawm cov khoom. Lub zog no yog siv los rhuav lossis tsim cov kev sib txuas ntawm cov molecule, tsis yog los ua kom cov khoom lub zog kinetic lossis qhov kub nce ntxiv.
Qhov txawv ntawm latent heat ntawm fusion thiab latent heat ntawm vaporization yog dab tsi?
- tebLub cua sov latent ntawm kev sib xyaw yog hais txog lub zog cua sov uas xav tau los hloov cov khoom los ntawm cov khoom khov mus rau cov kua (lossis vice versa) ntawm nws qhov chaw yaj. Lub cua sov latent ntawm kev ua pa yog hais txog lub zog cua sov uas xav tau los hloov cov khoom los ntawm cov kua mus rau cov roj (lossis vice versa) ntawm nws qhov chaw npau.
Vim li cas peb thiaj li txias thaum peb tawm hauv pas dej ua luam dej thaum hnub cua hlob, txawm tias huab cua sov los xij?
- tebThaum dej ua pa tawm ntawm peb daim tawv nqaij, nws hloov pauv theem ntawm kua mus rau pa. Cov txheej txheem no xav tau lub zog, uas raug coj los ntawm peb daim tawv nqaij hauv daim ntawv ntawm cua sov, ua rau peb daim tawv nqaij txias dua.
Vim li cas cov pa dej kub ntawm 100°C thiaj txaus ntshai dua li cov dej npau ntawm 100°C?
- tebCov pa dej muaj zog ntau dua li dej npau vim nws tau nqus cov cua sov latent ntawm kev ua pa thaum lub sijhawm hloov pauv ntawm dej mus rau pa. Thaum cov pa dej sib sau ua ke rau ntawm daim tawv nqaij, nws tso tawm cov zog ntxiv no, ua rau kub hnyiab ntau dua li dej npau.
Ntxiv ntsev rau hauv dej khov ua li cas thiaj txo nws qhov melting point?
- tebNtxiv ntsev ua rau qhov sib npaug ntawm qhov yaj thiab khov ntawm cov dej khov sib tov tsis sib haum. Qhov no ua rau cov dej khov yaj ntau dua ntawm qhov kub qis dua li niaj zaus, ua rau qhov khov ntawm cov khoom sib tov qis dua.
Vim li cas kev tawm hws thiaj pab ua kom lub cev txias rau hnub kub?
- tebCov hws, thaum ua pa tawm ntawm daim tawv nqaij, hloov pauv ntawm kua mus rau roj. Cov txheej txheem ua pa no xav tau lub zog, uas raug coj los ntawm daim tawv nqaij, yog li ua rau nws txias.
Sublimation nyob rau hauv cov ntsiab lus ntawm kev hloov pauv theem yog dab tsi?
- tebSublimation yog qhov hloov pauv ncaj qha los ntawm cov khoom khov mus rau cov roj yam tsis tau dhau los ntawm cov kua. Ib qho piv txwv feem ntau yog dej khov qhuav (khoom carbon dioxide) hloov pauv ncaj qha mus rau hauv cov roj carbon dioxide.
Vim li cas thiaj xav tau lub zog cua sov los yaj cov dej khov txawm tias qhov kub tseem nyob ntawm 0°C?
- tebLub zog cua sov yog siv los rhuav tshem cov kev sib txuas ntawm cov molecular uas tuav cov dej khov hauv nws cov qauv khov kho. Thaum cov kev sib txuas no raug rhuav tshem, cov dej khov hloov mus rau theem kua, txawm tias tsis muaj kev hloov pauv ntawm qhov kub thiab txias.
Lub siab cuam tshuam li cas rau qhov kub ntawm cov kua dej?

tebFeem ntau, kev nce lub zog sab nraud ua rau lub ntsiab lus npau ntawm cov kua dej nce siab, thaum txo lub zog ua rau lub ntsiab lus npau qis dua. Qhov no yog vim li cas dej npau ntawm qhov kub qis dua 100°C ntawm qhov chaw siab, qhov twg lub zog ntawm huab cua qis dua.