Fundamental Thermodynamic Relation

(noun)

In thermodynamics, the fundamental thermodynamic relation expresses an infinitesimal change in internal energy in terms of infinitesimal changes in entropy, and volume for a closed system in thermal equilibrium in the following way: dU=TdS-PdV. Here, U is internal energy, T is absolute temperature, S is entropy, P is pressure and V is volume.

Related Terms

Examples of Fundamental Thermodynamic Relation in the following topics:

  • Specific Heat for an Ideal Gas at Constant Pressure and Volume

    • It is easier to measure the heat capacity at constant pressure (allowing the material to expand or contract freely) and solve for the heat capacity at constant volume using mathematical relationships derived from the basic thermodynamic laws.
    • This equation reduces simply to what is known as Mayer's relation :
    • It is a simple equation relating the heat capacities under constant temperature and under constant pressure.
    • Julius Robert von Mayer (November 25, 1814 – March 20, 1878), a German physician and physicist, was one of the founders of thermodynamics.
    • He is best known for his 1841 enunciation of one of the original statements of the conservation of energy (or what is now known as one of the first versions of the first law of thermodynamics): "Energy can be neither created nor destroyed. " In 1842, Mayer described the vital chemical process now referred to as oxidation as the primary source of energy for any living creature.

  • The Second Law

    • The second law of thermodynamics deals with the direction taken by spontaneous processes.
    • If the process can go in only one direction, then the reverse path differs fundamentally and the process cannot be reversible.
    • The law that forbids these processes is called the second law of thermodynamics .
    • Like all natural laws, the second law of thermodynamics gives insights into nature, and its several statements imply that it is broadly applicable, fundamentally affecting many apparently disparate processes.
    • Contrast the concept of irreversibility between the First and Second Laws of Thermodynamics

  • The First Law

    • The first law of thermodynamics is a version of the law of conservation of energy specialized for thermodynamic systems.
    • In equation form, the first law of thermodynamics is
    • In this video I continue with my series of tutorial videos on Thermal Physics and Thermodynamics.
    • The change in the internal energy of the system, ΔU, is related to heat and work by the first law of thermodynamics, ΔU=Q−W.
    • Explain how the net heat transferred and net work done in a system relate to the first law of thermodynamics

  • Matter Exists in Space and Time

    • The principle topics covered in elementary mechanics are: fundamental abstracts, the Newtonian system, position and velocity, and Newton's second law.
    • This section re-introduces some fundamental terms and methods of science that form the basis of Engineering Thermodynamics.
    • To assist students in learning beginning-level thermodynamics; some review to set things straight is required.
    • Fundamental Abstracts: The accumulated observations of ourselves are categorized into our "knowledge. " From time to time, the essence of "all we know" is formulated as an abstract, being something we all agree that we know.
    • Examples of this section relate to representation of space as an origin, coordinates and a unit vector basis.

  • LTE

    • To derive these relations we have not made any assumptions about whether the photons or the matter are in thermal equilibrium with themselves or each other.
    • An extremely useful assumption is that the matter is in thermal equilibrium at least locally (Local Thermodynamic Equilibrium).
    • In this case the ratio of the number of atoms in the various states is determined by the condition of thermodynamic equilibrium
    • Because the source function equals the blackbody function, does this mean that sources in local thermodynamic equilibrium emit blackbody radiation?

  • Absolute Temperature

    • Thermodynamic temperature is the absolute measure of temperature.
    • It is one of the principal parameters of thermodynamics and kinetic theory of gases.
    • Thermodynamic temperature is an "absolute" scale because it is the measure of the fundamental property underlying temperature: its null or zero point ("absolute zero") is the temperature at which the particle constituents of matter have minimal motion and cannot become any colder.
    • By using the absolute temperature scale (Kelvin system), which is the most commonly used thermodynamic temperature, we have shown that the average translational kinetic energy (KE) of a particle in a gas has a simple relationship to the temperature:

  • The Third Law

    • According to the third law of thermodynamics, the entropy of a perfect crystal at absolute zero is exactly equal to zero.
    • The third law of thermodynamics is sometimes stated as follows: The entropy of a perfect crystal at absolute zero is exactly equal to zero.
    • Entropy is related to the number of possible microstates, and with only one microstate available at zero kelvin the entropy is exactly zero.
    • Absolute value of entropy can be determined shown here, thanks to the third law of thermodynamics.

  • Kelvin Scale

    • The Kelvin scale is an absolute, thermodynamic temperature scale using absolute zero as its null point.
    • In the classical description of thermodynamics, absolute zero is the temperature at which all thermal motion ceases.
    • The Kelvin scale is used extensively in scientific work because a number of physical quantities, such as the volume of an ideal gas, are directly related to absolute temperature.
    • The kelvin is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water (exactly 0.01°C, or 32.018°F).
    • A brief introduction to temperature and temperature scales for students studying thermal physics or thermodynamics.

  • Carnot Cycles

    • We know from the second law of thermodynamics that a heat engine cannot be 100 percent efficient, since there must always be some heat transfer Qc to the environment.
    • The second law of thermodynamics can be restated in terms of the Carnot cycle, and so what Carnot actually discovered was this fundamental law.
    • The second law of thermodynamics (a third form): A Carnot engine operating between two given temperatures has the greatest possible efficiency of any heat engine operating between these two temperatures.

  • Einstein Coefficients

    • For the system to be in thermodynamic equilibrium, the number of transitions from level one to two must equal the reverse transitions,
    • We know that since the system is in thermodynamic equilibrium with the radiation field $J_\nu=B_\nu(T)$
    • Because the Einstein coefficients are properties of the atom alone, they do not depend on the assumption of thermodynamic equilibrium.
    • If we calculate the probability of absorption of a photon for example, we can use the Einstein relations to find the rate of stimulated and spontaneous emission.