The Meaning of Temperature

A graph showing the vapor-pressure curve of iodine crystal and the vapor-pressure curve of liquid iodine. The melting point of the crystal is the temperature at which the crystal and the liquid have the same vapor pressure, and the boiling point of the liquid (at 1 atm pressure) is the temperature at which the vapor pressure of the liquid equals 1 atm. 

In the preceding discussion the assumption has been made that molecules move more rapidly and violently at any given temperature than at a lower one. This assumption is correct —the temperature of a system is a measure of the vigor of motion of all the atoms and molecules in the system. 

With increase in temperature there occurs increase in violence of molecular motion of all kinds. Gas molecules rotate more rapidly, and the atoms within a molecule oscillate more rapidly relative to one another. The atoms and molecules in liquids and solids carry out more vigorous vibrational motions. This vigorous motion at high temperatures may 

You can get a better understanding of many of the phenomena of chemistry by remembering that the absolute temperature is a measure of the vigor of the motion of atoms and molecules. 

Iodine vapor at elevated temperature this vapor contains both diatomic molecules (lo) and monatomic molecules (I) of iodine. 

---

Thus we see that the properties of gases provide a substantial basis for developing the atomic theory. The gaseous state is, in many ways, the simplest state of matter for us to understand. The regularities we discover are susceptible to detailed mathematical interpretation. We shall examine these regularities in this chapter. We shall find that their interpretation, called the kinetic theory, provides an understanding of the meaning of temperature on the molecular level. 

We have explored the meaning of temperature. According to the kinetic theory, when two gases are at the same temperature, the molecules of the two gases have the same average kinetic energies. Changing the temperature of a sample of gas at constant pressure reveals that the volume is di-... 

The ideal gas law can be derived solely from theoretical principles by making a few assumptions about the nature of gases and the meaning of temperature. The derivation can be found in any physical chemistry textbook. 

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

We first use the kinetic theory of gases to find a relation among pressure, volume, and the motions of molecules in an ideal gas. Comparing the result obtained with the ideal gas law (PV = nRT) provides a deeper understanding of the meaning of temperature. 

Temperature Control.— The meaning of temperature control can be extended to cover not only the control of temperatures, but also the control of processes through a knowledge of the temperatures involved. In this sense it has a very wide interest. A list of the industries in which temperature control is used in one way or another would cover nearly the entire field of industry. This discussion is confined to the field of high temperatures. 

The Meaning of Temperature Earlier we said that the average kinetic energy of a particle was equal to the absolute temperature times a constant, that is, Ey = constant X T. A derivation of the full relationship gives the following equation ... 

We. may wish to consider the mean of temperature or inverse temper-... 

Problems in Choice of a Reactor. When a process engineer is faced with the problem of designing a commercial or semicommercial unit, he must first choose the reactor to be used. The type of reactor (tube, tower, or tank), the type of operation (batch, continuous, recycle, or once-through), and the means of temperature control (isothennal or adiabatic) may depend on the type of reaction involved. In order to choose the best reactor and method of operation, the specific type of reacting system must be considered. 

To see how the meaning of temperature given above helps to explain gas behavior, picture a gas in a rigid container. As the gas is heated to a higher temperature, the particles move faster, hitting the walls more often. And, of course, the impacts become more forceful as the particles move faster. If the pressure is due to collisions with the walls, the gas pressure should increase as temperature is increased. 

Deriving the Ideal Gas Lauu The Meaning of Temperature Root Mean Square Velocity... 

Last decades the non-extensive thermodynamics has being developed to describe the properties of systems where the thermodynamic limit conditions are violated. It is not a purpose of this paper to give one more review of non-extensive thermodynamics, its methods and formalism. The reader can found it in numerous papers, reviews and books (see, for example, (Abe Okamoto, 2001 Abe et al., 2007 Gell-Mann Tsallis, 2004 Tsallis, 2009)). Here we would like to underline only that the definition of temperature is very close related to the existence of thermal equilibrium and is very sensitive to the thermodynamic limit conditions, so a researcher should be veiy careful in the prescribing the meaning of temperature to a Lagrange multiplier when entropy maximum is looked for. 

Units of Pressure Collecting a Gas over Water The Meaning of Temperature... 

The Central Importance of Kinetic Energy Recall from Chapter l that the kinetic energy of an object is the energy associated with its motion. It is key to explaining some implications of Avogadro s law and, most importantly, the meaning of temperature. 

Temperature and heat capacity are mo properties that are easy to measure, but not so easy to conceptualize. In this chapter, we develop a conceptual picture of temperature, heat capacity, and related quantities. We use two simple models—the ideal gas, and the two-state Schottky model of Chapter 10. Two-state systems can have negative temperatures (lower than T = OK). Negative temperatures help to illuminate the meanings of temperature and heat capacity in general. 

I AIMS To understand energy and its effect on matter. To understand the meanings of temperature and heat. 

Chapter 6 (Gases) makes increased use of the recommended units of pressure (e.g.. Pa, kPa, and bar). Section 6-7 on the kinetic-molecular theory has been significantly revised. For example, the subsection on Derivation of Boyle s Law has been simplified and now comes after the subsections on Distribution of Molecular Speeds and The Meaning of Temperature. Section 6-8 has also been revised so that Graham s law is presented first, as an empirical law, which is then justified by using the kinetic-molecular theory. 

---