Thermodynamics

Thermodynamics is the branch of science concerned with the nature of heat and its conversion to any form of energy. In thermodynamics, both the thermodynamic system and its environment are considered. A thermodynamic system, in general, is defined by its volume, pressure, temperature, and chemical make-up. In general, the environment will contain heat sources with unlimited heat capacity allowing it to give and receive heat without changing its temperature. Whenever the conditions change, the thermodynamic system will respond by changing its state; the temperature, volume, pressure, or chemical make-up will adjust accordingly in order to reach its original state of equilibrium. There are three laws of thermodynamics in which the changing system can follow in order to return to equilibrium.

In order for a system to gain energy the surroundings have to supply it, and visa versa when the system looses energy the surroundings must gain it. As the energy is transferred it can be converted form its original form to another as the transfer takes place, but the energy will never be created or destroyed. The first law of thermodynamics, also known as the law of conservation of energy, basically restates that energy can’t be destroyed or created “as follows: the total energy of the universe is a constant.” All around the conservation of energy is applied. When gasoline burns in the engine of a car, an equal amount of work and heat appear as the energy is released. The heat from the engine warms its surroundings, the cars parts, the air, and the passenger area. The heat energy is converted into the electrical energy of the radio, chemical energy of the battery, and radiant energy of the lights. The change in the sum of all of the energies formed from the burnt gasoline would be equal to the “…change in energy between the reactants and products.” Biological processes, like photosynthesis, also follow energy conservation. The green plants convert the radiant energy emitted by the Sun into useful chemical energy, such as the oxygen that we breathe. The energy transferred between any surroundings and any system can be in the form of various types of work, chemical, mechanical, radiant, electrical, or heat.

The second law of thermodynamics is expressed as a cycle that “all processes occur spontaneously in the direction that increases the entropy of the universe (system plus surrounding).” Entropy, the number of ways the components of a system can be rearranged without changing the system, plays a major roll in the second law of thermodynamics.