2019-05-15 10:56 admin

Let's convert the temperature of a substance from an equation to an infinitesimal change through a reversible process, and replace sub-Q with equation (4-11). We get ds a Q/dT.

We can see that if the heat capacity C is known, the entropy change from one state to another can be determined by integral (4-13). If the principle of entropy increase is changed in an isolated system, then the expression of the principle of entropy increase (4-11) will be changed to the expression of the principle of closed-O, sub-W-O, or d-O, dv-O. It shows that if the irreversible process is carried out in an isolated system, the entropy of the system must increase. If the reversible process is carried out, the entropy of the system will remain unchanged and the process of reducing the entropy of the system will not occur. The change of entropy is calculated by the heat of reversible process. Since the temperature is always positive, the heat absorption increases the entropy and the heat release decreases the entropy. When a substance changes from solid to liquid or from liquid to gas, it is always accompanied by heat absorption, so S gas is less S liquid and S solid. Material temperature must absorb heat, so S high temperature is less S low temperature.

Entropy is the property of a macroscopic system consisting of a large number of molecules. Statistical mechanics can also be used to study the properties of macro-system from the point of view of micro-motion. In statistical mechanics, the definition of Entropy Formula (4-15) is called Boltzmann Relation, that is, K in the formula is Boltzmann constant, gate is thermodynamic probability, and the total number of micro-states corresponding to a certain macro-state. The more the number of micro-states of the system, the greater the thermodynamic probability, the more chaotic the system, the greater the entropy. This is the essence of entropy.

If we examine natural processes, we will find that spontaneous processes in nature tend to form more disordered (or unorganized) structures. For example, rocks on the surface tend to weathering, minerals tend to dissociate and plants decay after death, so they can no longer use the energy of the sun. Therefore, in addition to heat flow, the degree of order is another factor that helps to determine whether a given process occurs or not. Again, the rock salt-water system absorbs heat when it reacts, but the overall change is that the orderliness of the system decreases. Originally sodium and chlorine atoms were arranged in an orderly manner and separated from water molecules, so that the two separate phases now become arbitrary distributions of sodium and chloride ions in the whole system, resulting in entropy values such as 25 due to the change of degree of order. At C, the entropy of graphite is larger than that of diamond. We can take this situation as a result of the fact that the volume of graphite per unit mass is larger than that of diamond of the same mass. The larger volume makes the carbon atom energy appear in a more disordered state, thus obtaining a higher entropy. Generally, the larger the difference of molar volume between two polymorphs, the larger the difference of entropy. Using the data in Table 1, we can find that the molar volumes of the common Si0 2 polymorphs have the same relationship between the entropy of the polymorphic quartz and that of the polymorphic quartz, i.e. the maximum value of the entropy of the polymorphic quartz. Because the temperature rise tends to increase the disorder of the atoms, it indicates that the stable high temperature of Si02 should correspond to the scale quartz. However, at the transition temperature of two phases, the entropy value of cristobalite is slightly higher, and it is a stable high temperature phase. Obviously, not only does the entropy of matter change with temperature, but the change of entropy of one substance may be greater than that of another substance. We can generalize the relationship between volume and entropy in batches. For most minerals, the larger the volume, the larger the entropy. If we increase the pressure on a mineral, it tends to shrink its volume. It is also found that the entropy of the mineral decreases when the pressure is increased.

In addition to volume, the entropy of any mineral is obviously related to a number of other factors. These factors include chemical composition, crystalline structure, degree of solid solution (if any) and type of bonding. Consider the effects of these factors on the ordering of atoms (ions) in minerals. Compared with another mineral, which has fewer components and is more orderly, the former's entropy should be noticed by Fang Fushiwen, which prevents the different right Nantangtian while Perfr7 spits out the back of the brain and village cloud T1 rises to T2. The equation that links the value of entropy with the absolute temperature and heat flux is applied to increase.

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