ความร้อน

1. 10
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2. – F ˆ F www.schoolDD.com 1
10
10.1 F
F ˈ ˂
F ˈ F F (Q) F ˈ (J)
- F 1 (= 4.186 J ) F F 1
1° C
10.1.1
ˈ F F
F F F F F
F F F
10.2.1 F F
F F ˈ F F F F F
F F F F F
F F F
1. (° C)
2. (K) ˈ F F F F F F F ( ˈ F
SI)
F
C =
R = F
F = F
K =
100
F F
0
° CK
373.16
273.16
K = C + 273
۱
૞
=
‫܀‬
૝
=
۴ି૜૛
ૢ

3. – F ˆ F www.schoolDD.com 2
10.1.2 F
1. F ( C ) F F
ˈ F F ˈ F (J/K)
2. F ( c ) F F 1 F
ˈ F F ˈ F (J/kg K)
F F F F F m ΔT F F
Q = F (J)
m = (kg)
c = F (J/kg K)
ΔT = (K ˚C)
- F ( C ) F F F C F C F
- F ( c ) F F ˈ
F c (J/kg K)
(-10˚C 0˚C)
4186
2100
900
450
390
140
130
m
∆Q
〉 ∆T
C =
ઢ‫ۿ‬
ઢ‫܂‬
m
∆Q
〉 ∆T
c =
ઢ‫ۿ‬
‫ܕ‬ઢ‫܂‬
Q = mc∆T

4. – F ˆ F www.schoolDD.com 3
F 1 F F 100 25˚C ( c = 390
J/kg K)
. ˈ 45 ˚C
. ˈ 15 ˚C
. F F F F F
Q = mc∆T
= 0.10x390x(45-25)
‫׵‬ Q = 780 J Ans
. F F F
Q = mc∆T
= 0.10x390x(25-15)
‫׵‬ Q = 390 J Ans
10.1.4 F
F F F F
F F F
F
- ˈ F
F F F F F F F
10.1.5 F
3
F F F F F
F F
F F F F F
F F F F F
F F F F F F F F F
F F ˂
s

5. – F ˆ F www.schoolDD.com 4
F F
F F m F F F
Q = F (J)
m = (kg)
L = F (J/kg)
F
Lm (J/kg)
F
ˈ Lv (J/kg)
333x103
2256x103
58.6x103
452x103
5.23x103
20.9x103
F 2 F F 200 -10˚ C ˈ
F ˈ F 190 ( c = 2100 J/kg K, c =
4186 J/kg K, Lm = 333x103
J/kg, Lv = 2256x103
J/kg )
“ F F ˈ
F F F F ˇ F F ”
F
F
F
F
Q = mL
200 g
-10° C
Q1
200 g
0° C
200 g
0° C
200 g
100° C
190 g + 10 g
100° C
Q2 Q3 Q4

6. – F ˆ F www.schoolDD.com 5
F F 200 g -10° C ˈ 0° C
Q1 = mc∆T
= 0.2x2100x(0-(-10))
Q1 = 4200 J
F F 200 g 0° C ˈ 0° C
Q2 = mL
= 0.2x333x103
Q2 = 66600 J
F F 200 g 0° C ˈ 100° C
Q3 = mc∆T
= 0.2x4186x(100-0)
Q3 = 83720 J
F F 10 g 100° C ˈ 10 g 100° C
Q4 = mL
= 0.01x2256x103
Q4 = 22560 J
‫׵‬ F Q = Q1 + Q2 + Q3 + Q4
= 4200 + 66600 + 83720 + 22560
Q = 177080 J Ans
F 3
100 100˚ C F F F ˈ
90˚ C (c = 4186 J/kg K, Lv = 2256x103
J/kg)
F 100 g 100° C F ˈ 100 g 100° C
Q1 = mLv
= 0.1x2256x103
(L = L F )
Q1 = 225600 J
F 100 g 100° C ˈ 100 g 90° C
Q2 = mc∆T
= 0.1x4186x(100-90)
Q2 = 4186 J
‫׵‬ F F Q = Q1 + Q2
= 225600 + 4186
Q = 229786 J Ans
100 g
100° C
100 g
100° C
Q1
100 g
90° C
Q2
“ F”

7. – F ˆ F www.schoolDD.com 6
F 4
F F 1 20 ˚C F ˈ -10 ˚C F
F F (c = 2100 J/kg K, c = 4186 J/kg K, Lm = 333x103
J/kg)
F 1 kg 20° C ˈ 1 kg 0° C
Q1 = mc∆T
= 1.0x4186x(20-0)
Q1 = 83720 J
F 1 kg 0° C ˈ 1 kg 0° C
Q2 = mLm
= 1.0x333x103
(L = L )
Q2 = 333000 J
F 1 kg 0° C ˈ 1 kg -10° C
Q3 = mc∆T
= 1.0x2100x(0-(-10))
Q3 = 21000 J
‫׵‬ F F Q = Q1 + Q2 + Q3
= 83720 + 333000 + 21000
Q = 437720 J Ans
10.1.6 F
F F F F
F F F F
F F F F
F = F F
F 5
F 200 F F 300˚ C F 1 20
˚C F F ˈ F ( c = 500 J/kg K, c = 4200 J/kg )
1 kg
20° C
1 kg
0° C
Q1
1 kg
0° C
Q3
1 kg
-10° C
Q2
Q = Q Q = Q
“ F”

8. – F ˆ F www.schoolDD.com 7
Q = Q
(mc∆T) = (mc∆T)
F F ˈ t° C 20 < t ≤100
F F 0.2x500x(300- t) = 1.0x4200x(t-20)
30000 - 100 t = 4200t – 84000
114000 = 4300t
‫׵‬ t = 26.5° C Ans ( )
F 6
F 5 F F ˈ 2 ˈ 0.5
F ˈ F
Q = Q
(mc∆T) = (mc∆T)
F F ˈ t° C 20 < t ≤100
F F 2.0x500x(300- t) = 0.5x4200x(t-20)
30000 - 100 t = 2100t – 42000
342000 = 3100t
‫׵‬ t = 110.3° C > 100° C F ˈ F ˈ
F ˈ 100° C F F
1 kg
20° C Q
1 kg
t° CQ
0.2 kg
300° C
Q
0.2 kg
t° CQ t ≤ 100° C F ˈ
t = 300° C F
100° C ˈ F
0.5 kg
20° C Q
0.5 kg
t° CQ
2 kg
300° C
Q
2 kg
t° CQ t ≤ 100° C F ˈ
t = 300° C F
100° C ˈ F
0.5 kg
20° C Q 1
0.5 kg
100° C
Q
2 kg
300° C
Q
2 kg
100° CQ
+
100° CQ 2

9. – F ˆ F www.schoolDD.com 8
ˈ F F
Q = Q
(mc∆T) = (mc∆T) 1 + (mL) 2
F F 2.0x500x(300-100) = 0.5x4200x(100-20) + mx2256x103
32000 = 2256x103
‫׵‬ m = 0.014 kg
ˈ 0.014 kg 100° C F F 0.5 0.014 = 0.486 kg 100° C Ans
F 7
˄ 1 2 20˚ C F F F 1
200 ˚C F ˈ F ( c = 1000 J/kg K, c
= 4200 J/kg c = 400 J/kg K )
Q = Q
(mc∆T) = (mc∆T) ˄ + (mc∆T)
F F ˈ t° C 20 < t ≤100
F F 1.0x400x(200- t) = 1.0x1000x(t-20) + 2.0x4200x(t-20)
80000 - 400 t = 1000t – 20000 + 8400 t - 168000
268000 = 9800t
‫׵‬ t = 27.35° C Ans ( )
F 8
F 200 1 30 ˚C F 100
0 ˚C F ( c F = 800 J/kg K, c = 4200 J/kg K,
L = 333x103
J/kg )
2 kg
20° C Q
2 kg
t° C
Q
1kg
200° C
Q
1kg
t° CQ
20 < t ≤ 100° C F ˈ
˄ 1 kg
20° C
˄ 1 kg
t° CQ ˁ

10. – F ˆ F www.schoolDD.com 9
Q = Q
(mc∆T) + (mc∆T) F = (mL) + (mc∆T)
F F ˈ t° C 0 < t < 30
F F 1.0x4200x(30- t) + 0.2x800x(30- t) = 0.1x333x103
+ 0.1x4200x(t-0)
4360x(30- t) = 33300 + 420t
97500 = 4780t
‫׵‬ t = 20.4° C Ans ( )
F 9
F 1 100 ˚C F 200 F
ˈ F ( c = 500 J/kg K, c = 4200 J/kg K, L = 333x103
J/kg )
Q = Q
(mc∆T) = (mL) + (mc∆T)
F F ˈ t° C 0 < t < 100
F F 1.0x500x(100- t) = 0.2x333x103
+ 0.2x4200x(t-0)
50000 - 500t = 66600 + 840t
-16600 = 1340t
1 kg
30° C Q
1 kg
t° C
Q
0.1 kg
0° C
Q
0.1 kg
0° C
Q 0 < t < 30° C
F 0.2 kg
30° C
F 0.2 kg
t° CQ F
Q
0.1 kg
t° C
1 kg
100° C Q
1 kg
t° C
Q
0.2 kg
0° C
Q
0.2 kg
0° C
Q
0 < t < 100° C
Q
0.2 kg
t° C

11. – F ˆ F www.schoolDD.com 10
‫׵‬ t = -12.39° C F ˈ F F ˈ 0° C
ˈ F
F F
Q = Q
(mc∆T) = (mL)
F F 1.0x500x(100- 0) = mx333x103
50000 = 333x103
m
‫׵‬ m = 0.15 kg = 150 g < 200 g OK
F F ˈ 0° C 0.15 kg Ans
10.1.7 F F
3
1. F
- F F F ˈ F F F
F F F
2. F
- F F ˈ F F F
F F F F F F F
F F F F F
3. F F
- F F F F F F F
F ˂
1 kg
100° C Q
1 kg
0° C
Q
0.2 kg
0° C
Q
+
0° C
Q

12. – F ˆ F www.schoolDD.com 11
10.2 F
- F F F F F F
F ˈ F
10.2.1 F
F ʽ F F
10.2.2 F
F ʽ F F
10.2.3 F
F F F
V ‫ן‬
୘
୔
୔୚
୘
= F
F
V ‫ן‬
૚
‫۾‬
P
1
V
T
PV = F
V ‫ן‬ T
V
T
P
୚
୘
= F
‫۾‬૚‫܄‬૚
‫܂‬૚
=
‫۾‬૛‫܄‬૛
‫܂‬૛
F F F
1 2 (T F )
F F P, V F F = F F F F T
F ˈ K F

13. – F ˆ F www.schoolDD.com 12
F
୔୚
୘
‫ן‬ n n = F =
୫
୑
F
n =
୒
‫ۼ‬‫ۯ‬
F 1 F 6.02x1023
F PV =
୒
‫ۼ‬‫ۯ‬
RT
F F KB =
ୖ
‫ۼ‬‫ۯ‬
= F F F =
଼.ଷଵ
଺.଴ଶ୶ଵ଴మయ
= 1.38x10-23
J/K
F PV = NKB T
PV = nRT PV = NKB T F F F F
F ˆ F F F
1. F PV = nRT
2. F F F P ‫ן‬ T, P ‫ן‬ n, V ‫ן‬ T, V ‫ן‬ n P ‫ן‬
ଵ
୚
F
3. F F F F F 1 2 F F F
F F
୔భ୚భ
୬భ୘భ
= R
୔మ୚మ
୬మ୘మ
= R
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
(P F ˈ P F )
F F
PV = nRT
ˈ F
R = F F = 8.31 J/mol K
. F
= 6.02 x 1023
F
1
‫۾‬૚‫܄‬૚
‫ܖ‬૚‫܂‬૚
=
‫۾‬૛‫܄‬૛
‫ܖ‬૛‫܂‬૛
F F F 1 2
F (T F )

14. – F ˆ F www.schoolDD.com 13
F 10
F 1 F 2 x 105
Pa 7˚ C F F F F
2 F F ˈ F
F PV = nRT
F F 2
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
P n
F
୚భ
୘భ
=
୚మ
୘మ
ଵ
ଶ଼଴
=
ଶ
୘మ
‫׵‬ T2 = 560 K 560 273 = 287° C Ans
F 11
F F 105
Pa F 27˚ C ˈ -3˚ C ˈ
F
F PV = nRT
F F 2
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
V n
V1 = 1 m3
P1 = 2x105
Pa
T1 = 273+7 = 280 K
n1
V2 = 2 m3
P2 = P1
T2 = ?
n2 = n1
V1
P1 = 2x105
Pa
T1 = 273+27= 300 K
n1
V2 = V1
P2 = ?
T2 = 273+(-3) = 270 K
n2 = n1

15. – F ˆ F www.schoolDD.com 14
F
୔భ
୘భ
=
୔మ
୘మ
ଵ଴ఱ
ଷ଴଴
=
୔మ
ଶ଻଴
‫׵‬ P2 = 0.9x105
Pa Ans
F 12
F F F 17˚ C F 2 x 105
Pa F
F ˈ 27˚ C F ˈ F (
=105
Pa)
F PV = nRT
F F 2
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
V n
F
୔భ
୘భ
=
୔మ
୘మ
ሺ୔ౝశ ౌబሻభ
୘భ
=
ሺ୔ౝశ ౌబሻమ
୘మ
F P F F ˈ P F F
ଶ୶ଵ଴ఱାଵ଴ఱ
ଶଽ଴
=
୔ౝమାଵ଴ఱ
ଷ଴଴
‫׵‬ Pg 2 = 2.09x105
Pa Ans
F 13
F 10 27˚ C 105
Pa F
F
V1
Pg1 = 2x105
Pa
T1 = 273+17= 290 K
n1
V2 = V1
Pg2 = ?
T2 = 273+27 = 300 K
n2 = n1

16. – F ˆ F www.schoolDD.com 15
F PV = nRT
F F F F
F F 105
(10x10-3
) = n (8.31)(300) 1 = 1000 cc = 1000 cm3
= 1000(10-6
m3
) = 10-3
m3
‫׵‬ n = 103
/ 2493 = 0.4 Ans
n =
୫
୑
m = nM
= 0.4x2.0x10-3
‫׵‬ m = 8.0x10-4
kg Ans
F 14
F 50 F 10 27˚ C
F F F F 5 17˚ C F F F
( R = 8.31 J/mol K, MN2 = 28 g/mol, 1 atm = 105
Pa )
. n1 F F P1 V1 = n1RT1
10x105
x50x10-3
= n1x8.31x300
n1 = 20
. n2 F F P2 V2 = n2RT2
5x105
x50x10-3
= n2x8.31x290
n2 = 10.4
‫׵‬ F F F n1 n2 = 20 10.4 = 9.6 9.6x28x10-3
= 0.27 kg Ans
V = 10
P = 105
Pa
T = 273+27 = 300 K
n = ?
m = ?
V1 = 50x10-3
m3
P1 = 10 atm
T1 = 273+27 = 300 K
n1 = ?
V2 = 50x10-3
m3
P2 = 5 atm
T2 = 273+17 = 290 K
n2 = ?

17. – F ˆ F www.schoolDD.com 16
F 15
F 64 27˚ C 20 F F
F ( R = 8.31 J/mol K, MO2 = 28 g/mol )
P F F PV = nRT
Px20x10-3
=
଺ସ
ଷଶ
x8.31x300 n =
୫
୑
‫׵‬ P = 2.493x105
Pa Ans
F 16
F 1 1.3 0˚ C 1
13 10 27˚ C
F PV = nRT
F F 2
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
F n =
୫
୑
M
F
୔భ୚భ
୫భ୘భ
=
୔మ୚మ
୫మ୘మ
ଵ୶ଵ
ଵ.ଷ୶ଶ଻ଷ
=
୔మ୶ଵ଴
ଵଷ୶ଷ଴଴
‫׵‬ P2 = 1.10 atm Ans
m = 64 g
T = 273+27 = 300 K
V = 20x10-3
m3
P = ?
V1 = 1
m1 = 1.3 g
T1 = 273+0 = 273 K
P1 = 1 atm
V2 = 10
m2 = 13 g
T2 = 273+27 = 300 K
P2 = ?

18. – F ˆ F www.schoolDD.com 17
F 17
F F F F
ˈ F
F PV = nRT
F F 2
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
F V T
F
୔భ
୬భ
=
୔మ
୬మ
୔భ
୬భ
=
భ
మ
୔భ
୬మ
‫׵‬ n2 = ½ n1 Ans
F 18
F F 10 kg/m3
27˚ C 2 F F
F 17˚ C 1 F F F
F PV = nRT
F F 2
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
F n =
୫
୑
M
V1
P1
T1
n1
V2 = V1
P2 = ½ P1
T2 = T1
n2 = ?
V1
T1 = 273+27 = 300 K
P1 = 2 atm
ߩ1 = 10 kg/m3
V2 = V1
T2 = 273+17 = 290 K
P2 = 1 atm
ߩ2 = ?

19. – F ˆ F www.schoolDD.com 18
F
୔భ୚భ
୫భ୘భ
=
୔మ୚మ
୫మ୘మ
୔భ
ౣభ
౒భ
୘భ
=
୔మ
ౣమ
౒మ
୘మ
୔భ
ఘభ୘భ
=
୔మ
ఘమ୘మ
ଶ
ଵ଴୶ଷ଴଴
=
ଵ
ఘమ୶ଶଽ଴
‫׵‬ ߩଶ = 5.17 kg/m3
Ans
10.3 F F
10.3.1 F
F
1. F F F ˈ
F F F
2. F F ˈ F
3. F ˈ F F F
10.3.2 F ( < EK > )
F F < EK > ˈ F F
1 F ˈ (J)
F F N F N< EK >
N< EK > =
ଷ
ଶ
NKB T
=
ଷ
ଶ
PV ( PV = NKB T )
=
ଷ
ଶ
nRT ( PV = nRT )
- < EK > F F F F F
< EK > = ૜
૛
KB T

20. – F ˆ F www.schoolDD.com 19
10.3.3 F
F F F vrms (vroot mean square )
F ˈ F (m/s)
- vrms F T M
- vrms F F (v) F F F
F 19
F 20 27˚ C ( R = 8.31 J/mol K, MH2 = 2 g/mol )
. F F
. F F
. vrms F
. < EK > = ?
< EK > =
ଷ
ଶ
KB T KB =
ୖ
୒ఽ
=
଼.ଷଵ
଺.଴ଶ୶ଵ଴మయ
= 1.38x10-23
=
ଷ
ଶ
x 1.38x10-23
x300
‫׵‬ < EK > = 6.21x10-25
J Ans
. N< EK > = ?
. N N = n NA
=
୫
୑
=
ଶ଴
ଶ
x 6.02x1023
N = 6.02x1024
‫׵‬ N< EK > = 6.02x1024
x 6.21x10-25
= 3.73 J Ans
vrms = ට
૜‫܂܀‬
‫ۻ‬
M = F 1 (kg)
m = 20 g
T = 273+27 = 300 K

21. – F ˆ F www.schoolDD.com 20
. vrms = ?
vrms = ට
ଷୖ୘
୑
= ට
ଷ୶଼.ଷଵ୶ଷ଴଴
ଶ௫ଵ଴షయ
= √3739500
‫׵‬ vrms = 1933.78 m/s Ans
F 20
F F F 3 10 2 Pa
. N N = n NA = 3x6.02x1023
F F N< EK > =
ଷ
ଶ
NKBT =
ଷ
ଶ
PV (‫׶‬ PV = NKBT)
=
ଷ
ଶ
x2x10x10-3
‫׵‬ N< EK > = 3x10-2
J Ans
F < EK > < EK > =
ଷ୶ଵ଴షమ
୒
=
ଷ୶ଵ଴షమ
ଷ୶଺.଴ଶ୶ଵ଴మయ
‫׵‬ < EK > = 1.66x10-26
J Ans
F 21
F F 2x 1025
F F 105
Pa
F F
F < EK > < EK > =
ଷ
ଶ
KBT
F N< EK > = ଷ
ଶ
NKBT =
ଷ
ଶ
PV (‫׶‬ PV = NKBT)
< EK > = ଷ
ଶ
୔୚
୒
= ଷ
ଶ
x
ଵ୶ଵ଴ఱ
ଶ୶ଵ଴మఱ
‫׵‬ < EK > = 7.5x10-21
J Ans
n = 3
V = 10 = 10x10-3
m3
P = 2 Pa
N<EK> = ?
<EK> = ?
N/V = 2x1025
/m3
P = 1x105
Pa
<EK> = ?

22. – F ˆ F www.schoolDD.com 21
F 22
F
. F F ˈ 2 F F ˈ F
. F F ˈ 2 F F ˈ F
.
< EK > =
ଷ
ଶ
KBT
F < EK > ‫ן‬ T
ழாేభவ
ழாేమவ
=
୘భ
୘మ
=
୘భ
ଶ୘భ
‫׵‬ < EK2 > = 2< EK1 > Ans
.
< EK > =
ଷ
ଶ
KBT
N< EK > = ଷ
ଶ
NKBT =
ଷ
ଶ
PV
F < EK > ‫ן‬ P N V
ழாేభவ
ழாేమவ
=
୔భ
୔మ
=
୔భ
ଶ୔భ
‫׵‬ < EK2 > = 2< EK1 > Ans
F 23
F A 1 7˚ C F B 2 27˚ C
F F ˈ F ( R = 8.31 J/mol K )
T1
<EK1>
T2 = 2 T1
<EK2> = ?
V1
P1
N1
<EK1>
V2 = V1
P2 = 2 P1
N2 = N1
<EK2> = ?
A
nA = 1
TA = 273 + 7 = 280 K
<EKA>
B
nB = 2
TB = 273 + 27 = 300 K
<EKB>
+

23. – F ˆ F www.schoolDD.com 22
N< EK > N< EK > =
ଷ
ଶ
NKBT
=
ଷ
ଶ
nRT
(N< EK >)A + (N< EK >)B = (
ଷ
ଶ
nRT)A + (
ଷ
ଶ
nRT)B
=
ଷ
ଶ
R(nATA + nBTB)
=
ଷ
ଶ
x8.31(1x280 + 2x300)
‫׵‬ F = 1.097x104
J Ans
F 24
F ˈ F F ( MH2 = 2 g/mol, MO2 =
32 g/mol)
vrms = ට
ଷୖ୘
୑
F vrms ‫ן‬
ଵ
√୑
T
୴౨ౣ౩ౄమ
୴౨ౣ౩ోమ
= ට
୑ోమ
୑ౄమ
= ට
ଷଶ
ଶ
= 4
‫׵‬ vrmsH2 = 4 vrmsO2 Ans
F 25
F ʽ F F ˈ 4 F
vrms ˈ F
vrms = ට
ଷୖ୘
୑
PV = nRT
F RT =
୔୚
୬
vrms = ට
ଷ୔୚
୬୑
H2
vrmsH2 O2
vrmsO2
ߩଵ
vrms1
ߩଶ = 4ߩଵ
vrms2

24. – F ˆ F www.schoolDD.com 23
= ට
ଷ୔
ఘ
୬୑
୚
=
୫
୚
= ߩ
F vrms ‫ן‬
ଵ
ඥఘ
P
୴౨ౣ౩భ
୴౨ౣ౩మ
= ට
ఘమ
ఘభ
= ට
ସఘభ
ఘభ
= 2
‫׵‬ vrms2 = 2 vrms1 Ans
10.4
-
- F F F F F
F U F F
F F ˈ F F F
F F F F F F F
F F
F F F U =
ଷ
ଶ
NKBT
=
ଷ
ଶ
nRT
=
ଷ
ଶ
PV
10.4.1 F 1 F F
F F F F
U = N< EK >
〉 ∆Q
〉 ∆U
〉 ∆W
∆Q = ∆U + ∆W
ΔW = FΔs
= PAΔs
= PΔV

25. – F ˆ F www.schoolDD.com 24
∆Q
F F F +
F -
∆U
+
-
∆W
+
F -
F 26
F F F 1000 J F F F 200 J F
F F F
∆Q = ∆U + ∆W
1000 = 200 + ∆W
∆W = 800
‫׵‬ F F = 800 J ( ∆W ˈ + ) Ans
F 27
F 1024
F F F F 1˚ C F F F F F F
(KB = 1.38x10-23
)
∆Q = ∆U + ∆W
=
ଷ
ଶ
NKB∆T + P∆V
=
ଷ
ଶ
x1024
x1.38x10-23
x1 + 0
∆Q = 20.7
‫׵‬ F F F F F ∆Q = 20.7 J Ans (∆Q ˈ + )
〉 ∆Q = 1000 J
〉 ∆U = 200 J
∆W = ?
〉 ∆Q = ?
N = 1024
∆T = 1
∆V = 0

26. – F ˆ F www.schoolDD.com 25
F 28
100 N F 1 F 1 K
F F F F 20 cm. ( R = 8.31 J/mol K )
∆Q = ∆U + ∆W
=
ଷ
ଶ
nR∆T + (-F∆s) ( F ˈ )
=
ଷ
ଶ
x1x8.31x1 – 100x0.20
∆Q = -7.5 ( ˈ F )
‫׵‬ F ∆Q = 7.5 J Ans
F 29
F F F F F F F
∆Q = ∆U + ∆W
=
ଷ
ଶ
NKB∆T + P∆V
=
ଷ
ଶ
P∆V + P∆V ( ‫׶‬ PV = NKBT)
∆Q =
ହ
ଶ
P∆V
‫׵‬ F F F F F ∆Q = ହ
ଶ
P∆V J Ans
n = 1
∆T = 1 K
∆Q = ?
F = 100 N
0.20
〉 ∆Q = ?
P
∆V
∆W
∆U

27. – F ˆ F www.schoolDD.com 26
F 30
F F F 20 27˚ C 105
Pa F
ˈ 57˚ C F F F F F F
V2 F
୔భ୚భ
୬భ୘భ
=
୔మ୚మ
୬మ୘మ
P n
F
୚భ
୘భ
=
୚మ
୘మ
ଶ଴
ଷ଴଴
=
୚మ
ଷଷ଴
V2 = 22
∆Q = ∆U + ∆W
=
ଷ
ଶ
NKB∆T + P∆V
=
ଷ
ଶ
P∆V + P∆V ( ‫׶‬ PV = NKBT)
=
ହ
ଶ
P∆V =
ହ
ଶ
x105
x(22-2)x10-3
∆Q = 500
‫׵‬ F F F F F ∆Q = 500 J Ans
〉 ∆Q = ?
V1 = 20
T1 = 273 + 27 = 300 K
P1 = 105
Pa
V2 = ?
T2 = 273 + 57 = 330 K
P2 = P1
∆W
∆U