Biological Sciences
High Specific Heat of Water
The high specific heat of water refers to its ability to absorb and retain heat without a significant change in temperature. This property is important in biological systems as it helps to stabilize the temperature of organisms and their environments. Water's high specific heat also plays a crucial role in regulating climate and weather patterns.
Written by Perlego with AI-assistance
Related key terms
1 of 5
5 Key excerpts on "High Specific Heat of Water"
eBook - PDFAir and Water
The Biology and Physics of Life's Media
- Mark Denny(Author)
- 2020(Publication Date)
- Princeton University Press(Publisher)
This relationship is the material's specific heat capacity, or, for short, its specific heat, Q s . For a gas, it matters whether specific heat is measured under conditions of constant pressure or of constant volume, the former being larger than the latter. For our purposes in this chapter, we are concerned with 146 Chapter 8 Table 8.1 Properties relating to the transport of heat in air. a gas (air) that under most biological conditions is free to expand, and therefore we use values for specific heat at constant pressure. The specific heats of materials are quite variable. Hydrogen, for instance, has a very high specific heat, about 14,000 J kg 1 K 1 . Gold is on the other end of the spectrum with a specific heat of only 130 J kg 1 K 1 . In general, gases have higher specific heats than liquids or solids. The specific heat of air is 1006 J kg 1 K 1 , a typical value for a gas. It varies negligibly across the biological range of temperature (table 8.1). Water, however, is an exception to the general rule. It has a very high specific heat for a liquid (table 8.2). In fact, with the exception of liquid ammonia, water has the highest specific heat of any room-temperature liquid, about 4200 J kg 1 K 1 , varying from 4218 at 0°C to 4179 at 40°C. It thus takes about four times as much heat to raise the temperature of a kilogram of water one degree as it does to raise the temperature of an equal mass of air.
eBook - PDF- William Moebs, Samuel J. Ling, Jeff Sanny(Authors)
- 2016(Publication Date)
- Openstax(Publisher)
We see from this table that the specific heat of water is five times that of glass and 10 times that of iron, which means that it takes five times as much heat to raise the temperature of water a given amount as for glass, and 10 times as much as for iron. In fact, water has one of the largest specific heats of any material, which is important for sustaining life on Earth. The specific heats of gases depend on what is maintained constant during the heating—typically either the volume or the pressure. In the table, the first specific heat value for each gas is measured at constant volume, and the second (in parentheses) is measured at constant pressure. We will return to this topic in the chapter on the kinetic theory of gases. Chapter 1 | Temperature and Heat 21 Substances Specific Heat (c) Solids J/kg · °C kcal/kg · °C [2] Aluminum 900 0.215 Asbestos 800 0.19 Concrete, granite (average) 840 0.20 Copper 387 0.0924 Glass 840 0.20 Gold 129 0.0308 Human body (average at 37 °C ) 3500 0.83 Ice (average, −50 °C to 0 °C ) 2090 0.50 Iron, steel 452 0.108 Lead 128 0.0305 Silver 235 0.0562 Wood 1700 0.40 Liquids Benzene 1740 0.415 Ethanol 2450 0.586 Glycerin 2410 0.576 Mercury 139 0.0333 Water (15.0 °C) 4186 1.000 Gases [3] Air (dry) 721 (1015) 0.172 (0.242) Ammonia 1670 (2190) 0.399 (0.523) Carbon dioxide 638 (833) 0.152 (0.199) Nitrogen 739 (1040) 0.177 (0.248) Oxygen 651 (913) 0.156 (0.218) Steam (100 °C) 1520 (2020) 0.363 (0.482) Table 1.3 Specific Heats of Various Substances [1] [1] The values for solids and liquids are at constant volume and 25 °C , except as noted. [2] These values are identical in units of cal/g · °C. [3] Specific heats at constant volume and at 20.0 °C except as noted, and at 1.00 atm pressure. Values in parentheses are specific heats at a constant pressure of 1.00 atm. In general, specific heat also depends on temperature. Thus, a precise definition of c for a substance must be given in terms of an infinitesimal change in temperature.
eBook - PDFEngineering Science N2 Student's Book
TVET FIRST
- MJJ van Rensburg(Author)
- 2016(Publication Date)
- Troupant(Publisher)
Note that heat capacity is an extensive property . In other words, it changes as the amount of the substance changes. For example, 100 g water will have a different heat capacity to 500 g of water. Because heat capacity applies only to a single object, specific heat capacity is a more useful property to work with because it does not depend on the amount of matter. Specific heat capacity The specific heat capacity ( c ) of a substance is the amount of heat energy required to raise the temperature of 1 kg (unit of mass) of the substance by one kelvin or 1 °C (unit of temperature). Note that the specific heat capacity is calculated per unit mass . The term specific heat is incorrect and we use the term specific heat capacity . The SI unit for specific heat capacity is joules per kilogram-kelvin (J/kg.K) or joules per kilogram-Celsius (J/kg.°C). Different substances have different specific heat capacities. The specific heat capacity ( c ) for pure water is 4,187 kJ/kg.K or 4,187 kJ/kg.°C. Specific heat capacity is an intensive property . For example, 100 g of water will have the same specific heat capacity as 500 g of water. Did you know? Water has the highest specific heat capacity of all liquids (except for liquid ammonia). It therefore takes a long time to heat and a long time to cool. Water’s high heat capacity has many useful practical applications. Here are a few examples: • Water is used as a coolant in car radiators. Due to its high specific heat capacity, water can absorb a large amount of heat energy from the engine of the car, but its temperature does not rise too high. • When used in firefighting, water absorbs the heat of the burning material and dissipates the heat as the water changes from liquid to gas. Water not only lowers the temperature of the fire but also increases the heat capacity of the material it comes into contact with, making it more difficult for the material to burn. Figure 7.5: We may use a hot water bottle to keep us warm on cold nights.
- Martha Mackin(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
The High Specific Heat of Water helps maintain body temperature; the vast quantity of water on Earth prevents large temperature variations between night and day. 12.6 Changes of state A. For water 1. General a) The three forms of water—ice, liquid, water vapor or steam— are chemically the same; only the arrangement of molecules is different. b) Adding or removing heat energy converts water from one state to another. 2. Changing from water to steam a) Boiling occurs when the vapor pressure of the liquid is equal to the external or the atmospheric pressure. b) For water the boiling point is 100° C at 1 atm (760 torr or 101.3 kPa). c) If the atmospheric pressure is less than 760 torr, the boiling point is less than 100° C; water boils at 95° C in Denver where atmospheric pressure is 630 torr. 282 Chapter Twelve d) If the external pressure is greater than 760 torr, the boiling point is higher than 100° C; in a pressure cooker, if the pres-sure increases to 1000 torr, water boils at 108° C; at 2 atm (1520 torr) the boiling point would be 120° C. e) Heat of vaporization is the energy needed to convert a liquid at its boiling point to a gas. 1) For water, the heat of vaporization is 9.72 kcal/mole (or 40.7 kJ/mole) or 540 cal/g (or 2.259 kJ/g). 2) The value, for water is high because of the hydrogen bond-ing between water molecules. f) Heat of condensation is the heat given off when a gas becomes a liquid; it is equal and opposite in sign to the heat of vaporization. x g) Heat of condensation is involved in exothermic processes; the heat of vaporization is endothermic. 3. Changing from ice to water a) Heat of fusion is the energy needed to convert a solid at its melting point to a liquid. 1) For ice, the heat of fusion is 1.44 kcal/mole (or 6.01 kJ/mole) or 80.0 cal/g (or 333 J/g). 2) The heat of fusion of ice is unusually high because of the attractive forces (hydrogen bonds) between water molecules.
eBook - ePub- R.A. Edwards(Author)
- 2014(Publication Date)
- Pergamon(Publisher)
This may be defined as the quantity of heat required to raise the temperature of 1 g of water by 1 degC. According to this definition, the specific heat of water measured in this unit is unity and is independent of temperature. The direct measurement of the specific heat of water in joules leads to the necessity of defining the mean calorie as equivalent to 4·1897 J. The kilocalorie (kcal) = 10 3 cal is also used, this being the heat required to raise the temperature of 1 kg of water by 1 degC. Particularly is it used in quoting the calorific values of foodstuffs (and in this connection it is somewhat confusingly referred to as the “calorie”). The continued use of these units (i.e. calories and kilocalories) is no longer really necessary and is falling, if somewhat slowly, from fashion. Also still in use, particularly by engineers, is the British thermal unit (B.t.u.) which is defined as the heat required to raise the temperature of 1 lb of water by 1 degF. It is equivalent to 778 ft-lb wt or approximately 1055 J. The therm is defined as 10 5 B.t.u. and is the unit used by the gas boards in expressing the energy consumed by coal-gas appliances and plants. The continuous-flow calorimeter may be used, in principle, to measure the specific heat of any liquid, but there must be a fairly plentiful supply of the liquid and a constant pressure head of this liquid must be arranged to ensure its uniform rate of flow over the heating element. Where less accuracy is required the direct method of electrical heating, as illustrated in Fig. 7.2, may be used. An electrically heated coil is submerged under the liquid in a copper calorimeter. In order to minimise heat losses this is well polished on its outside, stands on knife-edges of wood or cork and is surrounded by a water jacket as illustrated. This serves to provide a constant-temperature enclosure for the calorimeter. To give reasonable accuracy, the specific heat of the copper, of which the calorimeter is made, must be known
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
