Lipotso tsa mohlala tsa Molao-motheo o Motšo

Mehlala e 15 ea Lipotso tsa Molao-motheo oa Black

1. Leqhoa le boima ba 0,2 kg le kopantswe le tee e futhumetseng e nang le boima ba 0,2 kg. Mocheso wa leqhoa = – 10 ^o C, mocheso wa tee e futhumetseng = 40 ^o C. Mocheso o ikgethang wa leqhoa = 2100 J/kg C ^o , mocheso o ikgethang wa metsi = 4200 J/kg C ^o , mocheso wa ho kopanngwa ha metsi = 334.000 J/kg. Haeba leqhoa le tee e futhumetseng di kopantswe tsamaisong e kwalehileng e arohaneng, fumana mocheso wa ho qetela wa motsoako.

Puisano
Hoa tsebahala :
Boima ba leqhoa (m es) = 0,2 kg
Boima ba metsi a futhumetseng a tee (tei ea m) = 0,2 kg
Mocheso o itseng oa metsi (c metsi) = 4180 J/kg C^o
Mocheso o itseng oa leqhoa (c es) = 2100 J/kg C^o
Mocheso oa ho kopana ha metsi (L)_f metsi) = 334.000 J/kg
Mocheso oa leqhoa (T es) = -10^oC
Mocheso o futhumetseng oa metsi a tee (tee ea T) = 40^oC
E botsitsoe : mocheso oa ho qetela oa motsoako (motsoako oa T) ?
Jawab :
Mohato oa pele, hakanya boemo ba ho qetela.
Mocheso o lokelang ho ntšoa ke metsi ho theola mocheso oa 0,2 kg ea tee e futhumetseng ho tloha ho 40^oHo tloha ho C ho isa ho 0^oC:
Mocheso o monngoang ke leqhoa la 0,2 kg ho phahamisa mocheso oa lona ho tloha ho -10^oHo tloha ho C ho isa ho 0^oC:
Mocheso o monngoang ho qhibilihisa leqhoa la 0,2 kg (mocheso o hlokahalang ho fetola leqhoa lohle hore e be metsi):
Ho latela dipalo tse ka hodimo, ho fumanwe diphetho tse latelang:
Q e lokollotsoe = 33,444 kJ
Q e amohetsoeng = 4,2 kJ
Q e qhibilihang = 66,8 kJ

Ha tee e chesang e ntsha mocheso wa 33,44 kJ, mocheso wa tee e chesang o fetoha ho tloha ho 40oC ho ya ho 0oC. Mocheso o mong o lokollotsweng (o ka bang 4,2 kJ) o sebedisetswa ho phahamisa mocheso wa leqhoa ho tloha ho -10°C ho ya ho 0°C. ^oHo tloha ho C ho isa ho 0^oC. 33,44 kJ – 4,2 kJ = 29,24 kJ. Ho qhibilihisa leqhoa lohle ka metsing, ho hlokahala 66,8 kJ ya mocheso. Mocheso o setseng ke 29,24 kJ.

Ho ka fihlellwa qeto ya hore mocheso o lokollwang ke tee e futhumetseng o sebediswa feela ho phahamisa mocheso wa leqhoa ho tloha ho -10 ^oHo tloha ho C ho isa ho 0^oC mme e qhibilihisa karolo e 'ngoe ea leqhoa. Karolo e 'ngoe ea leqhoa e fetohile metsi, e 'ngoe ha e so fetohe. Nakong ea ts'ebetso ea ho fetoha ho tloha ho tiileng ho ea ho metsi, mocheso ha o fetohe. Ka hona, mocheso oa ho qetela oa motsoako ke 0^oC.

2. Boima ba tee e chesang = 0,4 kg, boima ba leqhoa = 0,2 kg, mocheso oa li-cubes tsa leqhoa = -10^oC, mocheso oa tee e chesang = 90^oC. Haeba ka bobedi di tswakane, mocheso wa ho qetela wa motswako ke ofe?
Puisano
Mohato oa pele: hakanya boemo ba ho qetela
Mocheso o lokelang ho ntšoa ke metsi ho theola mocheso oa 0,4 kg ea metsi a chesang a tee ho tloha ho 90^oHo tloha ho C ho isa ho 0^oC:
Mocheso o amohetsoeng ke leqhoa la 0,2 kg ho phahamisa mocheso oa lona ho tloha ho -10^oHo tloha ho C ho isa ho 0^oC:
Mocheso o hlokahalang ho qhibilihisa leqhoa la 0,2 kg (mocheso o hlokahalang ho fetola leqhoa lohle hore e be metsi):
Ho latela dipalo tse ka hodimo, ho fumanwe diphetho tse latelang:
Q e lokollotsoe = 150,48 kJ
Q e amohetsoeng = 4,2 kJ
Q e qhibilihang = 66,8 kJ
Ha tee e chesang e ntsha mocheso wa 150,48 kJ, mocheso wa tee e chesang o fetoha ho tloha ho 90oC ho ya ho 0oC. Mocheso o mong o lokollotsweng (4,2 J) o sebedisetswa ho phahamisa mocheso wa leqhoa ho tloha ho -10 oC ho ya ho 0oC. 150,48 kJ – 4,8 kJ = 146,28 kJ. Mocheso o setseng = 146,28 kJ.
Mocheso o hlokahalang ho qhibilihisa leqhoa lohle ka metsing ke 66,8 kJ feela. 146,28 kJ – 66,8 kJ = 79,48 kJ. Tee e chesang ha e hloke ho lokolla mocheso oa eona kaofela ho fihlela mocheso oa eona o theohela ho 0^oC. Qetellong, mocheso oa ho qetela oa motsoako o lokela ho ba moholo ho feta 0^oC.

Mohato oa bobeli: fumana mocheso oa ho qetela (T)
Mocheso o hlokahalang ho phahamisa mocheso oa leqhoa ho tloha ho -10^oHo tloha ho C ho isa ho 0^oC ke 4200 J.
Mocheso o hlokahalang ho qhibilihisa leqhoa lohle ka metsing (mocheso o patehileng) = 66.800 J
Mocheso o hlokahalang ho phahamisa mocheso oa metsi (metsi a bakoang ke ho qhibilihisa leqhoa lohle) ho tloha ho 0^oHo tloha ho C ho isa ho T^oC = (boima ba leqhoa) (mocheso o itseng oa metsi) (T - 0) = (0,2) (4180) (T) = 836 T
Mocheso o ntshwang ke tee e futhumetseng ho theola mocheso wa yona ho tloha ho 90oC ho ya ho T = (botenya ba metsi)(90-T) = (0,4)(4180)(90 – T) = 1672 (90-T) = 150.480 – 1672 T

 

3. Ligrama tse 60 tsa metsi mochesong oa likhato tse 90^oC (mocheso o itseng oa metsi = 1 cal.g^-1.^oC^-1) e kopantsoe le digrama tse 40 tsa metsi a tshwanang mochesong wa 25^oC. Haeba ho se na mabaka a mang a amang ts'ebetso ena, joale mocheso oa ho qetela oa motsoako ke…

A. 15,4 ^oC
B. 23,0 ^oC
C. 46,0 ^oC
D. 64,0 ^oC
E. 77,0 ^oC

Puisano
Hoa tsebahala :
Boima ba metsi 1 (m₁) = digrama tse 60
Mocheso oa metsi 1 (T)₁= 90^oC
Boima ba metsi 2 (m₂) = digrama tse 40
Mocheso oa metsi 2 (T)₂= 25^oC
Mocheso o itseng metsi (c) = 1 cal.g^-1.^oC^-1
E botsitsoe : suhu motsoako oa ho qetela
Jawab :
Mocheso o ntshwang ke metsi a mocheso o phahameng (Q e ntshwang) = mocheso o ntshwang ke metsi a mocheso o tlase (Q e ntshwang)
m₁ c (ΔT) = m₂ c (ΔT)
(60)(1)(90 – T) = (40)(1)(T – 25)
(60)(90 – T) = (40)(T – 25)
5400 – 60T = 40T – 1000
5400 + 1000 = 40T + 60T
6400 = 100T
T = 6400/100
T = 64^oC
Karabo e nepahetseng ke D.

4. Karolo ea aluminium e na le boima ba ligrama tse 500 'me e na le mocheso oa likhato tse 30 ^oC e kenngoa ka sejaneng se nang le metsi a boima ba ligrama tse 200 le mocheso oa 90 ^oC. Haeba mocheso o itseng oa aluminium o tsejoa e le 0,22 cal/g C^o 'me mocheso o itseng oa metsi ke 1 cal/g C^o, ebe mocheso oa ho qetela oa metsi le aluminium ke...
A. 20,3 ^oC
B. 42,2 ^oC
C. 68,7 ^oC
D. 80,5 ^oC
E. 100 ^oC
Puisano:
Yuniti ea boima, ligrama (g) ha e hloke ho fetoloa lik'hilograma (kg) hobane mocheso o itseng oa aluminium le mocheso o itseng oa metsi li hlahisoa ka cal/g C^o.
Hoa tsebahala :
m aluminium = 500 dikgerama
aluminium ea c = 0,22 cal/gC^o
Aluminium ea T = 30 ^oC
metsi = digrama tse 200
c metsi = 1 cal/gC^o
Metsi a T = 90 ^oC
E botsitsoe :
Mocheso oa ho qetela (T) oa metsi le aluminium?
Jawab :

Foromo ea mocheso : Q = (m)(c)(delta T)

Q metsi = = (200 grams)(1 cal/gC^o(90) ^oC – T)
Aluminium ea Q = (ligrama tse 500)(0,22 cal/gC^o)(T– 30 ^oC)

Foromo ea motheo ea Black :Q _tima =Q _monya

Metsi a na le mocheso o phahameng oa pele (90 ^oC) e le hore metsi a ntše mocheso, aluminium e be le mocheso o tlase oa pele (30 ^oC) e le hore aluminium e monye mocheso. Mocheso oa ho qetela oa motsoako oa metsi le aluminium o lokela ho ba tlase ho feta mocheso oa pele oa metsi le ho feta mocheso oa pele oa aluminium.
(ligrama tse 200)(1 cal/gC^o(90) ^oC – T) = (ligrama tse 500)(0,22 cal/g C^o)(T– 30 ^oC)
(200)(1)(90-T) = (500)(0,22)(T-30)
(200)(90-T) = (110)(T-30)
18000 – 200 T = 110 T – 3300
18000 + 3300 = 110 T + 200 T
21300 = 310 T
T = 68,7 ^oC
Mocheso oa ho qetela oa motsoako oa metsi le aluminium ke 68,7 ^oC.
Karabo e nepahetseng ke C.

5. Sekotwana sa tšepe se boima ba digrama tse 300 mochesong wa di-degree tse 80 ^oC e inetsoe ka har'a ligrama tse 200 tsa metsi ho 40 ^oC. Mocheso o itseng oa metsi = 1 cal/g C^oHaeba mocheso oa ho qetela oa motsoako oa tšepe le metsi e le 50^o C mme setshelo ha se monye mocheso, jwale mocheso o ikgethang wa tshepe ke…
A. 0,15 cal/g C^o
B. 0,22 cal/g C^o
C. 1,50 cal/g C^o
D. 4,8 cal/g C^o
E. 7,2 cal/g C^o
Puisano:
Hoa tsebahala :
m tšepe = digrama tse 300
Tšepe ea T = 80 ^oC
metsi = digrama tse 200
Metsi a T = 40 ^oC
c metsi = 1 cal/g C^o
Motsoako oa ho qetela oa tšepe le metsi = 50 ^oC
E botsitsoe :
tšepe?
Jawab :
Q tšepe = (m)(c)(delta T) = (300 dikgerama)(c tšepe)(80^oC - 50^oC) = (300 dikgerama)(c tshepe)(30 C^o)
Q metsi = (m)(c)(delta T) = (200 grams)(1 cal/g C^o(60)^oC - 50^oC) = (200 dikgerama)(1 cal/g C^o)(10 C^o)

Foromo ea motheo ea Black :Q _tima =Q _monya

Tšepe e na le mocheso o phahameng oa pele (80 ^oC) e le hore tšepe e ntše mocheso, metsi a be le mocheso o tlase oa pele (40 ^oC) e le hore metsi a monye mocheso.
(300 grams)(c tšepe)(30 C^o) = (ligrama tse 200)(1 cal/g C^o)(10 C^o)
(300)(c)(30) = (200)(1)(10)
9000 c = 2000
c = 2000 / 9000
c = 0,22 cal/g C^o
Mocheso o itseng oa tšepe ke 0,22 cal/g C^o.
Karabo e nepahetseng ke B.

6. Libolo tse peli tse tšoanang li na le mocheso o tšoanang oa 40 ^oC, libolo tsena tse peli li na le boima ba ligrama tse 10 le ligrama tse 40 ka ho latellana. Libolo tsena ka bobeli li kenngoa ka har'a mokelikeli, e le hore mocheso oa libolo tsena ka bobeli o nyolohele ho 60^oC. Haeba mocheso o itseng oa bolo e le 2 cal/gr C^o le khalori e le 1 = 4,2 Joules, joale phapang ea mocheso o monngoang ke bolo ka 'ngoe ke ...
A. 5,04 x 10³ Joule
B. 7,50 x 10³ Joule
C. 10,6 x 10³ Joule
D. 40 x 10³ Joule
E. 42 x 10³ Joule
Puisano:
Hoa tsebahala :
m₁ = 10 lik'hilograma
m₂ = 40 lik'hilograma
T₁ = T₂ = 40 ^oC
T _QETA = 60 ^oC
bolo ea c = 2 cal/gr C^o
E botsitsoe :
Phapang ke efe mochesong o monngoang ke bolo ka 'ngoe?
Jawab :
Mocheso oa libolo ka bobeli oa eketseha hobane libolo ka bobeli li tlameha ho monya mocheso.
Q₁ = (10 gr)(2 cal/gr C^o(60)^oC–40^oC) = (10 gr)(2 cal/gr C^o)(20 C^o) = 400 cal = (400) (4,2 J) = 1680 Joules
Q₂ = (40 gr)(2 cal/gr C^o(60)^oC–40^oC) = (40 gr)(2 cal/gr C^o)(20 C^o) = 1600 cal = (1600) (4,2 J) = 6720 Joules
Phapang mochesong o monngoang ke bolo ka 'ngoe:
6720 J - 1680 J = 5040 J = 5,04 x 10³ J
Karabo e nepahetseng ke A.

7. Metsi a boima ba digrama tse 200 mochesong wa 30°C a kopanngwa le metsi a belang a boima ba digrama tse 100 le mocheso wa 90°C. (Mocheso o itseng wa metsi = 1 cal.gram^-1° C^-1). Mocheso oa metsi a tsoakiloeng nakong ea tekano ea mocheso ke….

A. 10°C

B. 30°C

C. 50°C

D. 75°C

E. 150°C

Puisano

Hoa tsebahala hore :

Boima ba metsi 1 (m₁) = digrama tse 200

Mocheso oa metsi 1 (T)₁= 30^oC

Boima ba metsi 2 (m₂) = digrama tse 100

Mocheso oa metsi 2 (T)₂= 90^oC

Mocheso o itseng oa metsi (c) = 1 cal.gram^-1° C^-1

E botsitsoe : mocheso oa ho qetela oa motsoako

Karabo :

Mocheso o ntshwang ke metsi a mocheso o phahameng (Q e ntshwang) = mocheso o ntshwang ke metsi a mocheso o tlase (Q e ntshwang)

Karabo e nepahetseng ke C.

8. Ae ka ba ligrama tse 60 mochesong oa likhato tse 90^oC (mocheso o itseng oa metsi = 1 cal.g^-1.^oC^-1) e kopantsoe le digrama tse 40 tsa metsi a tshwanang mochesong wa 25^oC. Haeba ho se na mabaka a mang a amang ts'ebetso ena, joale mocheso oa ho qetela oa motsoako ke…

A. 15,4 ^{ho isa ho} C

B. 23,0 ^o C

C. 46,0 ^o C

D. 64,0 ^o C

E. 77,0 ^o C

Puisano

Hoa tsebahala hore :

Boima ba metsi 1 (m1 ₎ = 60 dikgerama

Mocheso oa metsi 1 (T)₁= 90^oC

Boima ba metsi 2 (m2 ₎ = 40 dikgerama

Mocheso oa metsi 2 (T)₂= 25^oC

Mocheso o itseng oa metsi (c) = 1 cal.g^-1.^oC^-1

E botsitsoe : mocheso oa ho qetela oa motsoako

Karabo :

Mocheso o ntshwang ke metsi a mocheso o phahameng (Q e ntshwang) = mocheso o ntshwang ke metsi a mocheso o tlase (Q e ntshwang)

Karabo e nepahetseng ke D.

9. Leqhoa le nang le boima ba M grams mochesong oa 0^oC, e kenngoe ka metsing a boima ba ligrama tse 340 mochesong oa likhato tse 20^oC e behiloe ka har'a sejana se khethehileng. Nka hore sejana ha se monye/se lokolle mocheso. Haeba L_es = 80 khalori g^-1, c_moya = 1 khalori g^{-1 o}C^-1, leqhoa lohle lea qhibiliha 'me tekano ea mocheso e fihlelloa mochesong oa 5^oC, joale boima ba leqhoa (M) ke…

A. 60 dikgerama

B. 68 dikgerama

C. digrama tse 75

D. 80 dikgerama

E. 170 dikgerama

Puisano

Hoa tsebahala hore :

Boima ba metsi (m) = digrama tse 340

Thempereichara ea leqhoa (T)_es= 0^oC

Thempereichara ea metsi (T)_moya= 20^oC

Mocheso oa tekano ea mocheso (T) = 5^oC

Mocheso oa ho kopana ha leqhoa (L)_es) = 80 cal g^-1

Mocheso o itseng oa metsi (c_moya) = 1 cal g^{-1 o}C^-1

E botsitsoe Boima ba leqhoa (M)

Karabo :

Molao-motheo o Motšo e bolela hore tsamaisong e koetsoeng e arohaneng, mocheso o lokolloang ke ntho e nang le mocheso o phahameng o tšoana le mocheso o monngoang ke ntho e nang le mocheso o tlase.

Mocheso o ntshwang ke metsi (Q e ntshwang) = mocheso o monngwang ke leqhoa (Q e monngwang)

Karabo e nepahetseng ke A.

Catatan :

Haeba ho boletsoe hore leqhoa le na le mocheso oa 0^o joale metsi a ntse a le sebopehong se tiileng. Haeba ho boletsoe hore mocheso oa metsi ke 0^oC ebe metsi a ka sebopeho sa metsi. Fapanya tšebeliso ea mantsoe a leqhoa le metsi. Hobane metsi a ntse a le ka sebopeho sa leqhoa kapa a tiile, mocheso o monngoang pele o sebelisoa ho qhibilihisa leqhoa lohle hore e be metsi, ka hona ka lehlakoreng le letona la equation e kaholimo, ho eketsoa mokhoa oa ho bala hore na mocheso o tla qhibilihisa leqhoa hakae (m_es L_es). Kamora hore leqhoa lohle le qhibilihe hore e be metsi, mocheso o eketsehileng o sebediswa ho phahamisa mocheso wa leqhoa ho tloha ho 0^oC e ba 5^oC.

10. Tšepe ea koporo mochesong oa likhato tse 100^oC e tšeloa ka metsing ka boima ba ligrama tse 128 le mocheso oa likhato tse 30. ^oC. Mocheso o itseng oa metsi 1 cal.g^-1oC^-1 'me mocheso o itseng oa koporo ke 0,1 cal.g^-1oC^-1Haeba tekano ea mocheso e etsahala mochesong oa likhato tse 36 ^oC, joale boima ba tšepe ke….

A. 140 dikgerama

B. 120 dikgerama

C. digrama tse 100

D. 80 dikgerama

E. 75 dikgerama

Puisano

Hoa tsebahala hore:

Mocheso oa koporo (T)₁= 100 ^oC

Mocheso o itseng oa koporo (c₁) = 0,1 cal.g^-1oC^-1

Boima ba metsi (m₂) = digrama tse 128

Thempereichara ea metsi (T)₂= 30 ^oC

Mocheso o itseng oa metsi (c₂) = 1 cal.g^-1oC^-1

Mocheso oa tekano ea mocheso (T) = 36 ^oC

O botsitse: Boima ba koporo (m₁)

Karabo:

Molao-motheo oa Black o bolela hore mocheso o lokolloang ke ntho e nang le mocheso o phahameng = mocheso o amoheloang ke ntho e nang le mocheso o tlase.

Karabo e nepahetseng ke B.

11. Likhilograma tse tharo tsa molamu o motsho o nang le mocheso o itseng oa 1400 J.kg^-1C^-1 mocheso 80^oC e qoelisoa ka metsing a 10 kg ka mocheso o itseng oa 4200 J.kg^-1C^-1Kamora hore tekano ea mocheso e hlahe, mocheso oa ho qetela oa motsoako ke 20^oC. Mocheso oa pele oa metsi ke….

A. 20 ^{ho isa ho} C

B. 18 ^o C

C. 14 ^o C

D. 12 ^o C

E. 10 ^o C

Puisano

Hoa tsebahala hore:

Boima ba loto (m₁) = 3 kg

Mocheso o itseng oa thini (c)₁) = 1400 J.kg^-1C^-1

Mocheso oa tin (T)₁= 80 ^oC

Boima ba metsi (m₂) = 10 kg

Mocheso o itseng oa metsi (c₂) = 4200 J.kg^-1C^-1

Mocheso oa tekano ea mocheso (T) = 20 ^oC

O botsitse: Mocheso oa pele oa metsi (T)₂)

Karabo:

Karabo e nepahetseng ke C.

12. Chelete ea tšepe ea 50 gram e futhumatsoa ho fihlela mochesong oa 85^oC, ebe e qoelisoa ka sejaneng se nang le ligrama tse 50 tsa metsi mochesong oa 29,8^oC (mocheso o itseng oa metsi = 1 cal.g^-1.^oC^-1Haeba mocheso oa ho qetela oa sistimi e le 37^oC mme re nke hore ha ho na phetoho mochesong ka har'a sejana, joale mocheso o itseng oa tšepe ke…

A. 0,12 cal.g^-1.^oC^-1

B. 0,30 cal.g^-1.^oC^-1

C. 1,50 cal.g^-1.^oC^-1

D. 4,8 cal.g^-1.^oC^-1

E. 7,2 cal.g^-1.^oC^-1

Puisano

Hoa tsebahala hore:

Boima ba chelete ea tšepe (m) = 50 grams

Mocheso oa pele oa chelete ea tšepe (T)₁= 85^oC

Boima ba metsi (m) = digrama tse 50

Mocheso oa pele oa metsi (T)₂= 29,8^oC

Mocheso o itseng oa metsi = 1 cal.g^-1.^oC^-1

Mocheso oa ho qetela oa sistimi (T) = 37^oC

O botsitse: Mocheso o itseng oa tšepe (c)

Karabo:

Molao-motheo oa Black o bolela hore mocheso o lokolloang = mocheso o monngoang. Mocheso o lokolloa ke chelete ea tšepe 'me mocheso o monngoa ke metsi, ho fihlela ho fihletsoe tekano ea mocheso.

Diyuniti tsohle di hlahiswa ka digrama kahoo ha ho hlokahale hore ho fetolwe diyuniti.

Q _tima =Q _monya

m_logam c ΔT = m_moya c ΔT

(50)(c)(85-37) = (50)(1)(37-29,8)

(50)(c)(48) = (50)(7,2)

(50)(c)(48) = (50)(7,2)

(c)(48) = 7,2

c = 7,2 / 48

c = 0,15 cal.g^-1.^oC^-1

13. Tšepe ea koporo mochesong oa likhato tse 100^oC e tšeloa ka metsing ka boima ba ligrama tse 128 le mocheso oa likhato tse 30. ^oC. Mocheso o itseng oa metsi 1 cal.g^{-1 o}C^-1 'me mocheso o itseng oa koporo ke 0,1 cal.g^{-1 o}C^-1Haeba tekano ea mocheso e etsahala mochesong oa likhato tse 36 ^oC, joale boima ba tšepe ke….

A. 140 dikgerama
B. 120 dikgerama
C. digrama tse 100
D. 80 dikgerama
E. 75 dikgerama

Puisano
Hoa tsebahala hore:
Mocheso oa koporo (T)₁= 100 ^oC
Mocheso o itseng oa koporo (c₁) = 0,1 cal.g^{-1 o}C^-1

Boima ba metsi (m₂) = digrama tse 128
Thempereichara ea metsi (T)₂= 30 ^oC
Mocheso o itseng oa metsi (c₂) = 1 cal.g^{-1 o}C^-1

Mocheso oa tekano ea mocheso (T) = 36 ^oC
Potso: Boima ba koporo (m₁)
Karabo:

Molao-motheo oa Black o bolela hore mocheso o lokolloang ke ntho e nang le mocheso o phahameng = mocheso o amoheloang ke ntho e nang le mocheso o tlase.
Koporo ea Q = Metsi a Q
m₁ c₁ ΔT = m₂ c₂ ΔT
(m₁)(0,1)(100-36) = (128)(1)(36-30)
(m₁)(0,1)(64) = (128)(1)(6)
(m₁)(6,4) = 768
m₁ = 768/6,4
m₁ = 120
Boima ba koporo ke digrama tse 120.
Karabo e nepahetseng ke B.

14. Dikhilograma tse tharo tsa molamu o motsho wa loto o nang le mocheso o itseng wa 1400 J.kg^-1 C^-1 mocheso 80^oC e qoelisoa ka metsing a 10 kg ka mocheso o itseng oa 4200 J.kg^-1 C^-1Kamora hore tekano ea mocheso e hlahe, mocheso oa ho qetela oa motsoako ke 20^oC. Mocheso oa pele oa metsi ke….

A. 20 ^oC
B. 18 ^oC
C. 14 ^oC
D. 12 ^oC
E. 10 ^oC

Puisano
Hoa tsebahala hore:
Boima ba loto (m₁) = 3 kg
Mocheso o itseng oa thini (c)₁) = 1400 J.kg^-1 C^-1
Mocheso oa tin (T)₁= 80 ^oC

Boima ba metsi (m₂) = 10 kg
Mocheso o itseng oa metsi (c₂) = 4200 J.kg^-1 C^-1

Mocheso oa tekano ea mocheso (T) = 20 ^oC
Ho batloa: Mocheso oa pele oa metsi (T)₂)
Karabo:
Q e lokollotsoe = Q e amohetsoe
Q tin = Q metsi
m₁ c₁ ΔT = m₂ c₂ ΔT
(3)(1.400)(80-20) = (10)(4.200)(20-T)
(4.200)(60) = (42.000)(20-T)
252.000 = 840.000 – 42.000 T
42.000 T = 840.000 – 252.000
42.000 T = 588.000
T = 588.000 / 42.000
T = 14
Mocheso oa pele oa metsi ke likhato tse 14^oC.
Karabo e nepahetseng ke C.

15. Leqhoa le nang le boima ba M grams mochesong oa 0^oC, e kenngoe ka metsing a boima ba ligrama tse 340 mochesong oa likhato tse 20^oC e behiloe ka har'a sejana se khethehileng. Nka hore sejana ha se monye/se lokolle mocheso. Haeba L_es = 80 khalori g^-1, c_moya = 1 khalori g^{-1 o}C^-1, leqhoa lohle le ile la qhibiliha mme tekatekano ea mocheso e fihlelletsweng mochesong oa 5^oC, joale boima ba leqhoa (M) ke…

A. 60 dikgerama
B. 68 dikgerama
C. digrama tse 75
D. 80 dikgerama
E. 170 dikgerama

Puisano
Hoa tsebahala :
Boima ba metsi (m) = digrama tse 340
Thempereichara ea leqhoa (T)_es= 0^oC
Suhu metsi (T)_moya= 20^oC
Mocheso oa tekano ea mocheso (T) = 5^oC
Mocheso oa ho kopana ha leqhoa (L)_es) = 80 cal g^-1
Mocheso o itseng oa metsi (c_moya) = 1 cal g^{-1 o}C^-1
E botsitsoe Boima ba leqhoa (M)
Jawab :

Molao-motheo o Motšo e bolela hore tsamaisong e koetsoeng e arohaneng, mocheso o lokolloang ke ntho e nang le mocheso o phahameng o tšoana le mocheso o monngoang ke ntho e nang le mocheso o tlase.
Mocheso o ntshwang ke metsi (Q e ntshwang) = mocheso o monngwang ke leqhoa (Q e monngwang)
m_moya c_moya (T) = m_es L_es +m_es c_moya (T)
(340)(1)(20-5) = M (80) + M (1)(5-0)
(340)(15) = 80M + 5M
5100 = 85M
M = 5100/85
M = digrama tse 60
Karabo e nepahetseng ke A.

Catatan :
Haeba ho boletsoe hore leqhoa le na le mocheso oa 0^o joale metsi a ntse a le sebopehong se tiileng. Haeba ho boletsoe hore mocheso oa metsi ke 0^oC ebe metsi a ka sebopeho sa metsi. Fapanya tšebeliso ea mantsoe a leqhoa le metsi. Hobane metsi a ntse a le ka sebopeho sa leqhoa kapa a tiile, mocheso o monngoang pele o sebelisoa ho qhibilihisa leqhoa lohle hore e be metsi, ka hona ka lehlakoreng le letona la equation e kaholimo, ho eketsoa mokhoa oa ho bala hore na mocheso o tla qhibilihisa leqhoa hakae (m_es L_es). Kamora hore leqhoa lohle le qhibilihe hore e be metsi, mocheso o eketsehileng o sebediswa ho phahamisa mocheso wa leqhoa ho tloha ho 0^oC e ba 5^oC.

Mohloli oa lipotso:

Lipotso tsa Fisiks tsa Tlhahlobo ea Naha bakeng sa Sekolo se Phahameng sa Thuto e Phahameng/Sekolo se Phahameng sa Mosebetsi