Work ( W) had been converted into heat ( Q) with 100% efficiency. When the experiment was completed, the apparatus remained unchanged except for a slight increase in the water temperature. By this and similar experiments, he established numerical relationships between heat and work. Joule caused work to be expended by rubbing metal blocks together in a large mass of water. In his study of the first law of thermodynamics, J. In information theory the term entropy is used to represent the sum of the predicted values of the data in a message. However, such an occurrence is so improbable as to be impossible from a practical point of view. It should be noted that the second law of thermodynamics is statistical rather than exact thus there is nothing to prevent the faster molecules from separating from the slow ones. This means that although energy cannot vanish because of the law of conservation of energy (see conservation laws), it tends to be degraded from useful forms to useless ones.

In other words the entropy of the universe as a whole tends toward a maximum. According to the second law of thermodynamics, during any process the change in entropy of a system and its surroundings is either zero or positive. Thus the entropy of the system has increased. Although no energy has been lost by the heat transfer, the energy can no longer be used to do work. Furthermore, the combined lukewarm bodies cannot unmix themselves into hot and cold parts in order to repeat the process. This heat flow can be utilized by a heat engine (device which turns thermal energy into mechanical energy, or work), but once the two bodies have reached the same temperature, no more work can be done. If the bodies are placed in contact, heat will flow from the hot body to the cold one. For example, consider a system composed of a hot body and a cold body this system is ordered because the faster, more energetic molecules of the hot body are separated from the less energetic molecules of the cold body. Originally defined in thermodynamics in terms of heat and temperature, entropy indicates the degree to which a given quantity of thermal energy is available for doing useful work-the greater the entropy, the less available the energy. There might be decreases in freedom in the rest of the universe, but the sum of the increase and decrease must result in a net increase.Entropy (ĕnˈtrəpē), quantity specifying the amount of disorder or randomness in a system bearing energy or information. The freedom in that part of the universe may increase with no change in the freedom of the rest of the universe. Statistical Entropy - Mass, Energy, and Freedom The energy or the mass of a part of the universe may increase or decrease, but only if there is a corresponding decrease or increase somewhere else in the universe.Qualitatively, entropy is simply a measure how much the energy of atoms and molecules become more spread out in a process and can be defined in terms of statistical probabilities of a system or in terms of the other thermodynamic quantities. Statistical Entropy Entropy is a state function that is often erroneously referred to as the 'state of disorder' of a system.

Phase Change, gas expansions, dilution, colligative properties and osmosis. Simple Entropy Changes - Examples Several Examples are given to demonstrate how the statistical definition of entropy and the 2nd law can be applied.A microstate is one of the huge number of different accessible arrangements of the molecules' motional energy* for a particular macrostate.

Instead, they are two very different ways of looking at a system.

Microstates Dictionaries define “macro” as large and “micro” as very small but a macrostate and a microstate in thermodynamics aren't just definitions of big and little sizes of chemical systems.

“Disorder” was the consequence, to Boltzmann, of an initial “order” not - as is obvious today - of what can only be called a “prior, lesser but still humanly-unimaginable, large number of accessible microstate it was his surprisingly simplistic conclusion: if the final state is random, the initial system must have been the opposite, i.e., ordered.

‘Disorder’ in Thermodynamic Entropy Boltzmann’s sense of “increased randomness” as a criterion of the final equilibrium state for a system compared to initial conditions was not wrong.

Units of entropy