Temperature scales absolute scale

The meaning of temperature in relation to molecular motion. The absolute zero of temperature. The Absolute scale or Kelvin scale. 

ABSOLUTE TEMPERATURE SCALE - A scale of temperature measurement in which zero degrees is absolute zero. 

F, F, F, color centers due to electron trapped at T temperature on absolute scale... 

The absolute temperature scale that corresponds to the Celsius scale is the Kelvin scale for the Fahrenheit scale, the absolute scale is called the Rankine scale. The Celsius scale reads 0 when the Kelvin scale reads 273 the Fahrenheit scale reads 0 when the Rankine scale reads 460. These relationships are shown in Figure 1. 

The KTTS depends upon an absolute 2ero and one fixed point through which a straight line is projected. Because they are not ideally linear, practicable interpolation thermometers require additional fixed points to describe their individual characteristics. Thus a suitable number of fixed points, ie, temperatures at which pure substances in nature can exist in two- or three-phase equiUbrium, together with specification of an interpolation instmment and appropriate algorithms, define a temperature scale. The temperature values of the fixed points are assigned values based on adjustments of data obtained by thermodynamic measurements such as gas thermometry. 

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. ... 

This relation is used to define the absolute temperature scale in terms of energy exchanged with reser-... 

The general temperature scale now in use is the Celsius scale, based nominally on the melting point of ice at 0°C and the hoiling point of water at atmospheric pressure at 100°C. (By strict definition, the triple point of ice is 0.01°C at a pressure of 6.1 mhar.) On the Celsius scale, absolute zero is -2 73.15°C. 

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. 

Fig. 4-5. An absolute temperature scale from the change of volume of a gas with temperature.

There are great advantages to an absolute temperature scale that has its zero point at — 273°C. Whereas the zero of temperature in the Centigrade scale is based upon an arbitrary temperature, selected because it is easily measured, the zero point of the absolute scale has inherent significance in the kinetic theory. If we express temperatures on an absolute temperature scale, we find that the volume of a fixed amount of gas (at constant pressure) varies directly with temperature Also, the pressure of a fixed amount of (at constant volume) varies directly with temperature. And, according to the kinetic theory, the kinetic energy of the molecules varies directly with the absolute temperature. For these reasons, in dealing with gas relations, we shall usually express temperature on an absolute temperature scale. 

We have remarked that a temperature of zero on the absolute temperature scale would correspond to the absence of all motion. The kinetic energy would become zero. Very interesting phenomena occur at temperatures near 0°K (the superconductivity of many metals and the superfluidity of liquid helium are two examples). Hence, scientists are extremely interested in methods of reaching temperatures as close to absolute zero as possible. Two low temperature coolants commonly used are liquid hydrogen (which boils at 20°K) and liquid helium (which boils at 4°K). Helium, under reduced pressure, boils at even lower temperatures and provides a means of reaching temperatures near 1°K. More exotic techniques have been developed to produce still lower temperatures (as low as 0.001°K) but even thermometry becomes a severe problem at such temperatures. 

The boiling points and freezing points in degrees Centigrade of certain liquids are listed below. Express these temperatures on the absolute temperature (degree Kelvin) scale. 

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

Temperature Scales A quantitative description of temperature requires the definition of a temperature scale. The two most commonly encountered in thermodynamics are the absolute or ideal gas (°A) scale and the thermodynamic or Kelvin (K) scale."... 

---