Russian

ENTROPY

Entropy of a system (Greek "entrop", from "en-" - "in" and "trop" - "transformation") is approximation measure to equilibrium. If under the conditions of energy constancy in a system the ability to change system condition is expressed much, then its entropy is little. If a system is in equilibrium, then its entropy is relatively high.

To designate entropy the symbol S is chosen. From the point of view of the thermodynamics (the second law of the thermodynamics) excess entropy ΔS = , where q is the heat of the reversible process, T is the temperature.

Entropy, in distinction from interior energy and enthalpy, has the unit of measurement of not only energy, but of energy divided by temperature. It represents heat energy, which is dissipated at a certain temperature, or, sum of power losses falling on one degree within the given temperature interval. Thus, entropy represents energy capacity of heat energy, and temperature represents intensity.

Loss of free energy at equilibrium attainment is accompanied either by transformation of energy into heat, or by increasing of entropy. Entropy is the measure of system disarray. The more system disarray is, the more its entropy is. Increasing of entropy means that many of spontaneous chemical reactions proceed without heat emission.