Thermodynamics (Greek: Thermos = 'hot' and dynamic = 'change') is the physics of energy, heat, work, entropy and the spontaneity of processes. Thermodynamics in close contact with statistical mechanics in which many thermodynamic relationships derived.
On systems where there is a process exchange matter or energy, classical thermodynamics is not related to reaction kinetics (speed of a reaction process takes place). For this reason, the use of the term "thermodynamics" usually refers to equilibrium thermodynamics. With this relationship, a key concept in thermodynamics is kuasistatik process, the idealized, the "super slow". Time-dependent thermodynamic processes are studied in non-equilibrium thermodynamics.
Because thermodynamics is not concerned with the concept of time, it has been proposed that should be called a thermostatic equilibrium thermodynamics. Law of thermodynamics is a general truth, and these laws do not depend on the details of the interactions or the systems being studied. This means they can be applied to a system where one does not know anything other than the balance of energy and matter transfer between them and the environment. Examples include estimates of the spontaneous emission Einstein in the 20th century and current research on the thermodynamics of black objects.
Thermodynamic system is part of the universe are taken into account. A real or imaginary boundary separates the system of the universe, called the environment. Classification system based on the thermodynamic properties of the boundary and the flows of matter, energy and entropy between the system and the environment.
There are three types of systems based on the type of exchanges that occur between system and environment:
1. Isolated systems: not exchanging heat, matter or work with the environment. An example of an isolated system is an insulated container, such as an insulated gas cylinder.
2. Closed systems: exchanging energy (heat and work) but it does not matter with their environment. Green house is an example of a closed system where heat exchange occurs but was not exchanged with the work environment.
3. Open systems: exchanging energy (heat and work) and matter with its environment. A boundary allowing matter exchange is called permeable. Ocean is an example of an open system.
In fact, a system can not be isolated completely from the environment, because there is little mixing, even if only via minimal gravitational attraction. In the analysis of an isolated system, energy into the system is equal to the energy leaving the system.
There are four basic law applicable in the thermodynamic system, namely:
1. Early law (Zeroth Law) of Thermodynamics
This law states that the two systems in equilibrium with a third system, then all three in mutual equilibrium with each other.
2. First Law of Thermodynamics
This law is related to the conservation of energy. This law states in the energy change from a closed thermodynamic system is equal to the total of the amount of heat energy supplied into the system and work done on the system.
The first law of thermodynamics is a statement about the universal law of conservation of energy and identifies heat transfer as a form of energy transfer. The most common statement of the first law of thermodynamics reads: The increase in internal energy of a thermodynamic system is proportional to the amount of heat energy added to the system minus the work done by the system to its environment.
Legal foundation was first laid by James Prescott Joule who through successful experiments concluded that heat and work can be converted to each other. The first explicit statement given by Rudolf Clausius in 1850: "There is a state function E, called the 'energy', the differential equal to the amount of work exchanged with the environment in an adiabatic process."
Law of conservation of energy: Energy can not be created and can not be destroyed / removed. But it can be transferred in various ways. Applications: The machines of energy generation and energy users. Everything is just a transfer of energy, does not create and remove.
3. Second Law of Thermodynamics
The second law of thermodynamics associated with entropy. This law states that the total entropy of an isolated thermodynamic system tends to increase with time, approaching its maximum value.
Law of balance / increase in entropy: Heat can not flow from a cold material into a more heat spontaneously. Entropy is the randomness level of energy. If one end of the material is hot, and cold the other end, said to be random, because there are concentrations of energy. It said low entropy. Once the flat is warm, is said to increase entropy.
Application: Refrigerator must have exhaust heat behind it, a temperature higher than the surrounding air. Because if it does not heat from the fridge could not wasted out. Kelvin-Planck formulation or the second law of thermodynamics says that is not possible to make a heat engine that works in a cycle that merely changing the heat energy obtained from a reservoir at a certain temperature completely into mechanical effort. The second law of thermodynamics says that heat flow has a direction, in other words, not all processes in the universe is reversible (irreversible). For example, if a polar bear sleeping in the snow, the snow will melt under his body because the heat from the body of the bear. However, the bear can not take the heat from snow to warm the body. Thus, the flow of heat energy has a direction, ie from hot to cold. One important application of the second law is the study of heat engines. Heat engine is the name for a tool that serves convert heat energy into mechanical energy.
In a car engine for example, heat energy from burning the fuel is converted into motion energy cars. But, in all heat engines we know that the conversion of heat energy into mechanical energy expenditure is always accompanied by flue gas, which brings a number of heat energy. Thus, only a portion of the heat energy from burning fuel that is converted to mechanical energy. Another example is the electric power generating machinery; coal or other fuels burned and the heat energy generated is used to convert water into vapor form. This steam is directed into the blades of a turbine, making the blades are spinning. Finally, the mechanical energy is used to drive round an electric generator.
4. Third Law of Thermodynamics
The third law of thermodynamics associated with the temperature of absolute zero. This law states that when a system reaches a temperature of absolute zero, all processes will cease and the entropy of the system will approach the minimum value. This law also states that the entropy of a perfect crystal structure objects at a temperature of absolute zero is zero.
Law temperature of 0 Kelvin (-273.15 Celsius): The theory of thermodynamics states that heat (and gas pressure) occurs due to kinetic motion in molecular scale. If the motion is stopped, the temperature of the material will reach 0 degrees kelvin.
Applications: Most metals can be superconductors at very low temperatures, because not a lot of randomness in the molecular scale kinetic movement that interfere with the flow of electrons.
by:
Arif Fadholi W. A (053711328)
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