Absolute zero Kelvin

This means that all substances have some entropy (dispersal of energy and/or matter, i.e. disorder) except when the substance is a pure, perfect, motionless, vibrationless crystal at absolute zero Kelvin. This also implies that the entropy of a substance can be expressed on an absolute basis. 

When zirconium is alloyed with niobium, it becomes superconductive to electricity at temperatures near absolute zero Kelvin (—273°C). 

Invited 12. Masao Morishita and Hiroaki Yamamoto (University of Hyogo) Thermal Spectroscopy of Mg48Zn52, Mg2Zn3, MgZn2 and Mg2Znn from Near Absolute Zero Kelvin Electronic Term Contributing to Heat Capacity, Electric Resistivity and Thermal Conductivity... 

In the field of not only traditional metallurgy but also recently developed nano-technology, it is very interesting and important what change is introduced when it is surrounded by other atoms. Such a change in electronic states has been investigated as chemical shift detected by X-ray (XPS) and UV (UPS) photoemission spectroscopy [1] as well as X-ray emission and absorption spectroscopy [2,3]. Also, such a chemical shift has been simulated by theoretical calculation [4]. However, many problems have been unsolved. In the case of XPS and UPS, since the most outer layers of substances are analyzed, the spectra are easily affected by absorbed gaseous molecules. Also, with the X-ray emission and absorption spectroscopy it is difficult to analyze the complicated X-ray transition states for substances composed of heavy metal elements. Therefore, a complementary method has been demanded for the spectroscopy such as XPS, UPS and X-ray emission and absorption spectroscopy. The coefficient y of the electronic contribution to heat capacity, Cp, near absolute zero Kelvin reflects the density of states (DOS) in the vicinity of Fermi level (EF) [5]. Therefore, the measurement of y is expected to be one of the useful methods to clarify the electronic states of substances composed of heavy metal elements. 

Figure 1.3 shows the relationships between (Cp/T) and (T2) near absolute zero Kelvin (T2<14K2) for Mg2Zn3 [11]. In the same way, the Cp values of Mg48Zn52... 

Absolute temperature (5.6) Temperature measured on a scale whose zero point is absolute zero. Kelvin is the most common absolute temperature scale, and Rankine is another example. 

Absolute The temperature relative to absolute zero, expressed in Kelvin. Also called thermodynamic temperature. 

The volume of a gas would theoretically be zero at a temperature of approximately -273°C or -460°F. Tliis temperature, wliich lias become known as absolute zero, is tlie basis for tlie definition of two absolute temperature scales, tlie Kelvin (K) and Rankine (°R) scales. The former is defined by shifting tlie Celsius scale by 273-Celsius degrees so that 0 K is equal to -273°C. Equation (4.2.3) shows tliis relation. 

Carnot s research also made a major contribution to the second law of thermodynamics. Since the maximum efficiency of a Carnot engine is given by 1 -T( H, if the engine is to be 100 percent efficient (i.e., Cma = 1), Tc must equal zero. This led William Thomson (Lord Kelvin) to propose in 1848 that Tf must be the absolute zero of the temperature scale later known as the absolute scale or Kelvin scale. ... 

In the study of refrigeration, the Kelvin or absolute temperature scale is also used. This starts at absolute zero and has the same degree intervals as the Celsius scale, so that ice melts at + 2 73.16 K and water at atmospheric pressure boils at + 373.15 K. 

Absolute temperature, 57 Kelvin scale, 58 Absolute zero, 58... 

The maximum amount of work obtainable from a given quantity of heat, called its motivity by Lord Kelvin (1852), is thus always less than the mechanical equivalent of the quantity of heat, except in the limiting case when the refrigerator is at absolute zero (T2 = 0). It cannot be specified in terms of the condition of the body from which the heat is taken, or into which the heat passes, but requires in addition a knowdedge of the lowest available temperature, T2. For if we had another body at temperature T0, where T0 < T2, which could be used as a refrigerator, the amount of work ... 

Equation (4.2) requires that the total area above 0 Kelvin be obtained, but heat capacity measurements cannot be made to the absolute zero of temperature. The lowest practical limit is usually in the range from 5 K to 10 K, and heat capacity below this temperature must be obtained by extrapolation. In the limit of low temperatures, Cp for most substances follows the Debye low-temperature heat capacity relationship11 given by equation (4.4)... 

Figure 10.14a shows such a plot for Kr.10 The straight line below 7 2 = 4 K2 (Ts= 2 K) demonstrates the validity of equation (10.160). A graph similar to the one shown in Figure 10.14a was used in Chapter 4 to extrapolate Cr resultsgg to zero Kelvin when we used the Third Law to obtain absolute entropies. 

A triple point is a point where three phase boundaries meet on a phase diagram. For water, the triple point for the solid, liquid, and vapor phases lies at 4.6 Torr and 0.01°C (see Fig. 8.6). At this triple point, all three phases (ice, liquid, and vapor) coexist in mutual dynamic equilibrium solid is in equilibrium with liquid, liquid with vapor, and vapor with solid. The location of a triple point of a substance is a fixed property of that substance and cannot be changed by changing the conditions. The triple point of water is used to define the size of the kelvin by definition, there are exactly 273.16 kelvins between absolute zero and the triple point of water. Because the normal freezing point of water is found to lie 0.01 K below the triple point, 0°C corresponds to 273.15 K. 

Absolute temperature The lowest possible temperature is absolute zero. The absolute temperature scale starts there and increases in increments of 1 degree Celsius. The unit of measurement is the kelvin (K). 

The graphical plot of the temperature versus volume of a gas produces a straight line. If several different gases are studied and the temperature-volume data is plotted, the extrapolations of these graphs all intersect at the same temperature, -273°C. The Kelvin equivalent of this temperature is expressed as 0 K, or absolute zero. The mathematical expression to change Celsius temperature to Kelvin is K = C° + 273°. 

In a similar way, the Systeme Internationale has defined other common physicochemical variables. The SI unit of temperature T is the kelvin. We define the kelvin as 1/273.16th part of the thermodynamic temperature difference between absolute zero (see Section 1.4) and the triple point of water, i.e. the temperature at which liquid water is at equilibrium with solid water (ice) and gaseous water (steam) provided that the pressure is 610 Pa. 

Kelvin then replotted his data, this time extrapolating each graph till the volume of the gas was zero, which he found to occur at a temperature of -273.15 °C see Figure 1.5. He then devised a new temperature scale in which this, the coldest of temperatures, was the zero. He called it absolute zero, and each subsequent degree was equal to 1 °C. This new scale of temperature is now called the thermodynamic (or absolute) scale of temperature, and is also sometimes called the Kelvin scale. 

Celsius degrees and Kelvin degrees are the same size. The Kelvin scale begins at absolute zero. This is the temperature at which the particles in a substance have no kinetic energy. Therefore, Kelvin temperatures are never negative. By contrast, 0°C is set at the melting point of water. Celsius temperatures can be positive or negative. 

Kelvin scale a temperature scale that begins at the theoretical point of absolute zero kinetic energy, or -273.15°C each unit (a kelvin) is equal to 1°C... 

Absolute zero. Minus 273°C or minus 460 or 0°K or Kelvin, the scale used in theoretical physics and chemistry. Absolute zero is the theoretical temperature at which all molecular activity ceases. In practical terms, the lowest reachable temperature is about 1°K. 

When a gas is cooled by 1 °C, from 0°C to —1 °C, it loses l4 3 of its pressure. Since pressure is due to movement of the gas molecules, Lord Kelvin realised that a gas would have no pressure at -273 °C that is, there would be no movement of the gas molecules -273 °C is absolute zero. Since the rate of a reaction depends upon the movement and hence collision of molecules, the relevant temperature scale for chemical (and therefore biochemical) reactions is one whose zero is -273 °C. It is known as the Kelvin or absolute scale. 

Figure 3.10 Temperature scales Celsius and Kelvin (absolute). On the Celsius scale, absolute zero is -273 °C. The temperature at which water boils is, therefore, 373 °K. Most life on earth exists only between 277 and 293 °K.

The compound consisting of yttrium, copper, and barium oxide, commonly called compound 1-2-3, was formed in 1987 by research scientists at the universities of Alabama and Houston. It had limited superconducting capabilities. It has been known for some time that conductors of electricity such as copper resist, to some extent, the flow of electrons at normal temperatures, but at temperatures near absolute zero (zero Kelvin = -273°C), this resistance to the flow of electrons in some materials is reduced or eliminated. The 1-2-3 compound proved to be superconducting at just 93°K, which is still much too cold to be used for everyday transmission of electricity at normal temperatures. Research continues to explore compounds that may achieve the goal of high-temperature superconductivity. 

Niobium alloyed with germanium becomes a superconductor of electricity that does not lose its superconductivity at 23.2° Kelvin as large amounts of electrical current are passed through it, as do some other superconductive alloys. In the pure metallic state, niobium wires are also superconductors when the temperatures are reduced to near absolute zero (—273°C). Niobium alloys are also used to make superconductive magnets as well as jewelry. 

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