That is,
m copper c copper T 1 À T final
À
Á
copper
¼ m water c water T final À T 1
À
Á
water
This may be alternatively expressed in terms of the conservation of “total
heat”,
m cop c cop T 1
ð Þ cop þ m wat c wat T 1
ð Þ wat ¼ m cop c cop þ m wat c wat
Â
Ã
T final
The final temperature is, thus,
T final ¼
m cop c cop T 1
ð Þ cop þ m wat c wat T 1
ð Þ wat
m cop c cop þ m wat c wat
¼
10 gm
½ Š  0:0921 cal/gm Á C
½
ŠÂ60 C
½ Š þ 100  1  30
10 Â 0:0921 þ 100 Â 1
¼ 30:274
C
Table 2.1 Latent heat for common substances
Substance
Latent heat of fusion
(cal/g)
Melting point
(°C)
Latent heat of
vaporization (cal/g)
Boiling
point (°C)
Alcohol,
ethyl
25.8
−114
204.3
78.3
Ammonia
79.36
−77.74
327.1
−33.34
Carbon
dioxide
43.96
−78
137.14
−57
Helium
5.02
−268.93
Hydrogen
13.86
−259
108.7
−253
Lead
5.5
327.5
208.1
1750
Nitrogen
6.14
−210
47.78
−196
Oxygen
3.32
−219
50.89
−183
Refrigerant
R134a
−101
51.58
−26.6
Refrigerant
R152a
−116
78.01
−25
Toluene
17.23
−93
83.86
110.6
Turpentine
70
Water
79.8
0
539.96
100
2.2 Direct Heating: Sensible Heat and Latent Heat
31