Thermodynamics Basics

Thermodynamics is the science of studying the changes that occur within a system in relation to its interaction with its surroundings according to a series of laws formulated that are considered valid for all systems. Thermodynamics allows scientists to study the potential reactions and interactions of systems that exist only in theory, or be such that they cannot be recreated or contained in a laboratory for study.

History

Otto von Guericke built the first vacuum pump in 1650 to disprove Aristotle's belief that "nature abhors a vacuum" creating the world's first documented vacuum which became known as the Magdeburg hemispheres and bringing the discipline of thermodynamics into being. In1656, Robert Boyle and Robert Hooke built an air pump based upon Guericke's design and discovered Boyle's law, which states that pressure and volume are inversely proportional. Denis Papin continued from their design, building a bone digester in 1679 which used a closed vessel with a lid to confine steam until a high pressure was produced. In 1697, Thomas Savery, using Papin's work, built the first piston and cylinder engine.
In 1824, Sadi Carnot published Reflections on the Motive Power of Fire, which discussed heat, power and engine efficiency. This publication outlined the relationship between the Carnot engine, the Carnot cycle, and Motive Power. Carnot is considered to be the "father of thermodynamics"" and his work, the starting point of this modern science.
In 1849, James Joule was the first person to use the term thermodynamics when describing the relationship between heat and power. Joule's experiments and the work of Benjamin Johnson codified the first law of thermodynamics, that the internal energy of a system is equal to the external heat and energy applied minus the amount lost to its surroundings.
Willard Gibbs, in the late 1800's, is considered to have given the study of thermodynamics its purpose by applying abstract thought and logical reasoning in reviewing his predecessors work and recognizing that this first law could be applied to non-homogeneous bodies and held key to the understanding chemical equilibrium.

Significance

With any given system, as long as a scientist knows at least the balance of energy and matter transfer, the laws of thermodynamics can be applied to generate a description of how that system will respond to changes in its surroundings. This enables scientists to learn about the behavior of systems that we do not know, or cannot bring into a laboratory to study, one example of such a system would be a black hole. The results of these studies can prove essential to other fields of physics, chemistry and engineering. The ability to predict and describe a systems response to change in their surroundings without having to test the system itself, which may be an impossible option, gives to science a wealth of data to work in advancing many other fields of expertise.

Function

Thermodynamics provides for a series of laws that are considered to be valid for almost all systems because the laws are not derived from the details of the system being studied, but from the reaction of the systems energy and matter transferring in response to change.
The four main laws of Thermodynamics are:
• The Zeroth Law - if two systems each are in equilibrium with a third system, then they must are also be in thermal equilibrium with each other.
• The First Law - if heat is added to a system, some of that energy stays in the system and some leaves the system.
• The Second Law - no reaction is 100% efficient and all energy wants to flow and spread to areas with less energy.
• The Third Law -- it is impossible to cool an object to absolute zero because all processes will cease before absolute zero is reached, this is commonly called the state of entropy.
These laws of allow for scientists to test theories in the laboratory for validity and then construct from those theories new systems created by what was learned from the response. For example, thermodynamic experimentation on the reaction of certain types of metals and structures to the environment of space, done through an understanding of how matter and energy would behave in a void, allowed for scientists to pursue the creation of materials that enabled us to explore space. The use of thermodynamics meant that they could do so without having to recreate the void and test every idea within the void to eliminate what did not work. The equations, guided by the laws of thermodynamics, were enough to allow the scientist to formulate working prototypes.

Types

There are three types of recognized Thermodynamic Systems:
• Isolated -- this is a system that is not influenced by its surroundings in any way. An example of this would be an insulated coffee thermos, the system is the interior of the thermos that contains the coffee, the temperature or motion outside of the thermos does not effect the state of the coffee.
• Closed -- this system does not transfer mass but may transfer energy (through heat or work) with its surroundings. A simple example of this would be an non-insulated coffee cup with a lid. The coffee is exchanging heat, but not work, with its surroundings.
• Open -- this system transfers both mass and energy with its surroundings. Using coffee as an example again, coffee poured onto the ground forms an open system both exchanging its heat with its surroundings and work, through its saturation of its surroundings.

Theories/Speculation

Theories associated with Thermodynamics follow one these three forms:
1. Classical -- these theories focus on the thermodynamic states and properties such as energy, work and heat of a system.
2. Statistical -- this is the most popular method for the exploration of theories as it takes into consideration the statistical mechanics of the system and the reaction including measuring temperature, volume, pressure, energy, and entropy as well as the exchange of heat and work.
3. Chemical -- this studies the chemical reactions, or physical change of a state as it relates to heat within the confines of the laws of thermodynamics.

Resources

• More on Thermodynamic Systems and Processes
• Lectures from a Basic Course in Thermodynamics