Heat A form of energy that flows between

Halides, 562 Hall, Charles, 3,536 Halogen An element of Group 17,31 oxidizing power of 557 oxoacids of, 567t reactivity, 559 Head-to-head polymer, 613 Head-to-tail polymer, 613 Heat A form of energy that flows between two samples because of their difference in temperature, 197,214 Heat capacity The amount of heat required to raise the temperature one degree Celsius, 199... 

Heat A form of energy that flows between two samples of matter because of their difference in temperature, measured in joules (J). 

Although we commonly use expressions like "heat is lost," "heat is gained," "heat flows," and "the system loses heat to the surroundings," you should not take these statements to mean that a system contains heat. It does not. The energy content of a system, as we shall see in Section 7-5, is a quantity called the internal energy. Heat is simply a form in which a quantity of energy may be transferred across a boundary between a system and its surroundings. 

To derive the condition for thermodynamic equilibrium, we start with an isolated system consisting of two subsystems as shown in Figure 5.6. Subsystem A is the one of primary interest in that it is the one in which the chemical process is occurring. Subsystem B is a reservoir in contact with subsystem A in such a way that energy in the form of heat or work can flow between the two subsystems. If left alone, the system will come to equilibrium. Energy will be transferred between the subsystems so that the temperature and pressure will be... 

There are many examples of nonequilibrium states. A classic example of a NESS is an electrical circuit made out of a battery and a resistance. The current flows through the resistance and the chemical energy stored in the battery is dissipated to the environment in the form of heat the average dissipated power, Pdiss = VI, is identical to the power supplied by the battery. Another example is a sheared fluid between two plates or coverslips and one of them is moved relative to the other at a constant velocity v. To sustain such a state, a mechanical power that is equal toVoc r v has to be exerted on the moving plate, where p is the viscosity of water. The mechanical work produced is then dissipated in the form of... 

In conduction, heat is conducted by the transfer of energy of motion between adjacent molecules in a liquid, gas, or solid. In a gas, atoms transfer energy to one another through molecular collisions. In metallic solids, the process of energy transfer via free electrons is also important. In convection, heat is transferred by bulk transport and mixing of macroscopic fluid elements. Recall that there can be forced convection, where the fluid is forced to flow via mechanical means, or natural (free) convection, where density differences cause fluid elements to flow. Since convection is found only in fluids, we will deal with it on only a limited basis. Radiation differs from conduction and convection in that no medium is needed for its propagation. As a result, the form of Eq. (4.1) is inappropriate for describing radiative heat transfer. Radiation is... 

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