What is Thermodynamic: Definition and 499 Discussions

Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, radiation, and physical properties of matter. The behavior of these quantities is governed by the four laws of thermodynamics which convey a quantitative description using measurable macroscopic physical quantities, but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to a wide variety of topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering and mechanical engineering, but also in other complex fields such as meteorology.
Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Nicolas Léonard Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Scots-Irish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854 which stated, "Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency."
The initial application of thermodynamics to mechanical heat engines was quickly extended to the study of chemical compounds and chemical reactions. Chemical thermodynamics studies the nature of the role of entropy in the process of chemical reactions and has provided the bulk of expansion and knowledge of the field. Other formulations of thermodynamics emerged. Statistical thermodynamics, or statistical mechanics, concerns itself with statistical predictions of the collective motion of particles from their microscopic behavior. In 1909, Constantin Carathéodory presented a purely mathematical approach in an axiomatic formulation, a description often referred to as geometrical thermodynamics.

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  1. S

    How Can Temperature Affect the 2nd Virial Coefficient in Thermodynamics?

    Homework Statement I am trying to quantify the 2nd Virial Coefficient depending on the temperature w/o using statistical mechanics b/c we haven't covered it yet. Homework Equations p=p_{ideal} [1+B_{2}(T) \frac{N}{V}] p_{ideal}= \frac{N k_{b} T}{V} The Attempt at a Solution Now other than...
  2. S

    Question: Fuel Cell Thermodynamic Equations

    I'm an undergrad working on fuel cells for a project and I have been using a book to aid me. There are several equations in the book that were not explained properly so I was hoping someone on this forum could help identify how they were derived. The first 2 is related to the pressure within...
  3. K

    Thermodynamic stabilitiy of colloidal systems

    Are all suspensions, emulsions and foam thermodynamically unstable?
  4. K

    Work Done on Thermodynamic Path ABCA: 5625 J

    Homework Statement The pressure and volume of a gas are changed along a path ABCA in the figure. The vertical divisions on the graph represent 2.5 multiplied by 105 Pa, and the horizontal divisions represent 1.5 multiplied by 10-3 m3. Determine the work done (including algebraic sign) in each...
  5. 0

    Exploring Methods for Deriving Derivatives from Thermodynamic Measurement Data

    Maybe this counts as computational physics, or statistics I don't know where this topic belongs. Ok so I have this nice high quality Thermodynamic measurement data and I have to start the "data raping" for results. Let's call the series A(t), and B(t) and I have a few more. So for different...
  6. A

    Sudden change in thermodynamic system.

    Do sudden changes occur in thermodynamic systems? If so, when do they occur and why? More specifically: When a system is nearing thermodynamic equilibrium, will the process always be slow, gradual, and uniform; or do sudden changes — sudden jumps — sometimes occur?
  7. S

    Thermodynamic cycle, work, energy heat input solving

    Homework Statement An ideal diatomic gas, in a cylinder with a moveable piston undergoes the rectangular cyclic process shown below. Assume that the temperature is always such that the translational and rotational degrees of freedom are active but the vibrational modes are "frozen out". Also...
  8. B

    Thermodynamic Entropy Clarification

    Homework Statement We mix 0.6 kg of water at a temperature of 25°C with 0.8 kg of alcohol at 30.5°C. They come to equilibrium. (Here's some useful data: The specific heat capacity for water is 1 kcal/kg°C = 4186 J/kg°C, and for alcohol it is 0.58 kcal/kg°C = 2430 J/kg°C What is the change...
  9. S

    Calculating Heat for Temperature Changes in a Rigid Container | Thermodynamics

    Homework Statement A rigid container holds 0.680 g of hydrogen gas. How much heat is needed to change the temperature of the gas From 50 K to 100 K? From 250 K to 300 K? From 550 K to 600 K? From 2250 K to 2300 K? The Attempt at a Solution I calculated the first one using delta E_th =...
  10. A

    Solve Thermodynamics: 7.67 kg Lead & 764 g Water Boiling Pt

    Homework Statement Suppose 7.67 kg of molten (liquid) lead at its melting point is poured into 764 g of water at 53.3o C. How much of the water boils? Homework Equations mc(detla T) = m(water)c(detla T). The Attempt at a Solution i m guessing i have to do the dollowing: mc(detla...
  11. D

    Two Closed Thermodynamic Cycles Conceptual Question

    Imagine processing the gas clockwise through Cycle 1 and then counterclockwise through Cycle 1. Compare these two processes on the basis of the heat energy transferred to the gas in the entire cycle. Choose the correct comparison symbol. Q_clockwise for Cycle 1 <,=,> Q_counterclockwise for...
  12. S

    Thermodynamic problem, mastering physics

    Homework Statement A 3000 cm3 container holds 0.10 mol of helium gas at 300C. How much work must be done to compress the gas to 1000 cm3 at constant pressure? How much work must be done to compress the gas to 1000 cm3 at constant temperature? The attempt at a solution W = integration...
  13. V

    Setup Thermodynamic Cycle for Enthalpy of Hydration of Mg2+ Ions

    Homework Statement Set up thermodynamic cycle for determining the enthalpy of hydration of Mg2+ ions The following enthalpies are given Sublimation of Mg ionization energies of Mg dissociation enthalpy of Cl2 electron gain enthalpy of Cl enthalpy of solution of MgCl2(s) enhalpy of...
  14. J

    Thermodynamic identity (non-quasistatic?)

    Homework Statement A cylinder contains one liter of air at room termperature and atmospheric pressure. At one end of the cylinder is a massless piston, whose surface area is 0.01 m^2. Suppose that you push the piston _very_ suddenly, exerting a force of 2 kN. The piston moves only one...
  15. V

    Thermodynamic polytropic compression

    Homework Statement I'm reading through my textbook and doing examples on polytropic process. I see this step and cannot figure out how the textbook gets V3 = 0.0169 m3 P2V2n = P3V3n (500 kPa)(0.05364 m3)1.2 = (2000 kPa)V31.2 V3 = 0.01690 m3 Homework Equations Not sure what to add...
  16. A

    Temperature Change in Adiabatic Process for Ideal Monatomic and Diatomic Gases

    Homework Statement a) By how much does the temperature of an ideal monatomic gas change in an adiabatic process in which 2.0 kJ of work are done on each mole of gas? b) By how much does the temperature of an ideal diatomic gas (with molecular rotation but no vibration) change in an adiabatic...
  17. L

    Thermodynamic Application Isothermal Work

    Homework Statement One mole of an ideal gas does 3000 J work on its surroundings as it expands isothermally to a final pressure of 1 atm and volume 25 L. Determine a) initial volume and b) Temp of gas Homework Equations The Attempt at a Solution Well, its isothermal, so Temp is...
  18. J

    Thermodynamic problem using ideal gas( me (T_T) )

    Homework Statement hi, can anyone help me with this problem? a motorist equips his automobile tire with a relief type valve so that the pressure inside the tire never exceeds 240 KPA(gage). He starts a trip with a pressure of 200 KPA(gage) and a temp. 23'C in the tires.During the long...
  19. Saladsamurai

    Thermodynamic Cycles: Understanding Energy Balance and Work-Energy Relations

    Homework Statement I have filled in a couple of spots as seen below, but I am a little confused as to how to proceed. If I get a good hint on one, I am sure the rest will follow. I think I am overlooking something obvious here. I know that in a cyclic process, all E (internal)...
  20. A

    Why are only five out of eight possible thermodynamic potentials important?

    Starting from the equation dE=tdS-PdV+\mu dN It is straightforward to derive all 8 possible thermodynamic potentials. My question is the following: Why are the only important potentials Entropy Helmholtz free energy Enthalpy Gibbs free energy Grand potential ? Why aren't the other three as...
  21. K

    Estimation of Work in Gas Compression - Thermodynamic

    What kind of thermodynamic process is the compression of a gas when the volume varies reducing it, and the temperature increase, and there is an exchange of temperature with the exterior (the walls of the compressor are refrigerated, but I assume that the gas will increase its temperature a...
  22. T

    Thermodynamic Compressor Question

    Homework Statement If there's a polytropic process (n = 1.51) compressor that compresses air (Ideal Gas) as: In: 100 kPa @ 25c Out: 30 MPa Given Data: Mass (m) = 105 kg, Work done by compressor (W) = 160000 kJ a. What is the exit temperature of the air from the compressor? b. If an...
  23. N

    Thermodynamic ( quanity of heat)

    [SOLVED] Thermodynamic ( quantity of heat) Homework Statement Calculate he quantity of heat that needed to transfer 2,0 kg ice of -10C to steam/vapor of 100C The process in this case take place in a good heat-isolated container with heat capacity of 500J/KgHomework Equations Q=mcT Q+-ml...
  24. S

    Second law of thermodynamic question

    A steam turbine in a power plant accepts 4500 kg/hr of steam at 60 bar and 500°C and exhausts steam at 10 bar. Heat transfer to the surroundings (Tsurr = 300K) at a rate of 70 kW. (a) What condition needs to be satisfied for the turbine to generate the maximum possible power? (2 marks) (b)...
  25. T

    Little help with thermodynamic question

    the question is in the attachment. All i really want to know is when you have to find the final pressure and temperature do you use the equation p1 v1^k = p2 v2^k where k is the the polytrophic index thanks
  26. V

    Formation of elements under conditions of thermodynamic equilbrium

    [Sorry about the long post] I'm doing an essay where I am exploring whether or not elements were, for the most part, formed under conditions of thermodynamic equilibrium. We know that some element clearly aren't (such as Potassium 40 and uranium which decay radioactivly). I've scoured the web...
  27. Y

    Solve Thermodynamic Signs Homework: W C → A, Q A → B, etc.

    Homework Statement A thermodynamic system changes isochorically from state A to state B where the temperature is greater than state A. The system then expands isobarically to state C where the temperature is greater than state B. From state C the system returns to its original state A linearly...
  28. S

    Thermodynamic problem, .

    Homework Statement An air-conditioning system is to be filled from a rigid container that initially contains 5 kg of liquid R-134a at 24 degrees Celsius . The valve connecting this container to the air-conditioning system is now opened until the mass in the container is .25 kg, at which...
  29. S

    Thermodynamic Question: Calculating Air Mass & Heat Transfer in a 2m3 Tank

    Please help... A stationary, un-insulated 2m3 rigid tank initially contains air at 100 kPa and 22oC. Air is available in an attached supply line at constant values of 600 kPa and 22oC. The valve to the supply line is opened and air enters the tank until the tank pressure reaches the...
  30. O

    A thermodynamic question

    a cylindrical tank of height 2m with a cross sectional area of 0.5m^2 contains hot water at 80oC , 125kPa.it is in a room with temperature To=20oC , so it slowly loses energy to the room air proportional to the temperature difference as Qloss=CA(T-To) with the tank surface area,A, C is a...
  31. ~christina~

    How does an ideal gas temperature change when it goes through a cycle?

    [SOLVED] 2 Thermodynamic questions Homework Statement 1. a) Determine the work done on a fluid that expands from i to f as indicated in picture below. b) How much work is performed on the fluid if it is compressed from f to i along the same path...
  32. F

    Heat Capacity and First Thermodynamic Law

    I have a question about the deduction of First Thermodynamic Law. The book that I have is written by Paul A. Tipler and Gene Mosca and it is called Physics: For Scientists and Engineers. The way to deduct it is given here: @constant volume, Qv=Cv(T2-T1) Because W=0, E2-E1=Cv(T2-T1)...
  33. D

    What is the Work Done on an Ideal Gas Under Isothermal Compression?

    An ideal gas originally at a temperature T1 and pressure P1 is compressed recersibly against a poston to a volume equal one-half of its original volume. The temperature of the gas is caried during the compression so that at each instant the relatoion P=AV is satisfied, where A is constant. Find...
  34. M

    Work by an ideal gas in a thermodynamic cycle

    1. Homework Statement Two moles of an ideal gas are carried around the thermodynamic cycle shown in Fig. 18-29. The cycle consists of (1) an isothermal expansion A to B at a temperature of 700 K, with the pressure at A given by pA = 9 atm; (2) an isobaric compression B to C at PC = 4 atm...
  35. M

    Volume of gas in a thermodynamic cycle.

    Homework Statement A 1 mol sample of an ideal gas for which c'V = 3R/2 follows the closed thermodynamic cycle shown in Fig. 18-36. There are three legs in the cycle: an isothermal expansion, A B; an isobaric compression, B C; and a constant-volume increase in pressure, C A. The...
  36. M

    Work by an ideal gas in a thermodynamic cycle

    Homework Statement Two moles of an ideal gas are carried around the thermodynamic cycle shown in Fig. 18-29. The cycle consists of (1) an isothermal expansion A to B at a temperature of 700 K, with the pressure at A given by pA = 9 atm; (2) an isobaric compression B to C at PC = 4 atm; and...
  37. E

    Thermodynamic Limit: Compute & Understand Model

    Can someone give an example of how to compute the "thermodynamic limit" of some model? I am very confused by this concept.
  38. R

    Solving Thermodynamic Problem: Outlet Temp of Pipe Carrying Water

    Hi, after a while of searching through a thermodynamics book and not really finding what I'm looking for I come to you all with my problem :D Here it is: I am required to write a formula which will allow me to determine the outlet temperature of a pipe carrying water for any given flow...
  39. G

    Working fluid for a thermodynamic cycle.

    I am looking for a liquid with a high thermal expansion coefficient. This liquid should act as a working fluid in an thermodynamic cycle based on a system where the working fluid act in the same phase (liquid phase) throughout the cycle. So far I have found pentane as one of the most...
  40. M

    Thermodynamic potentials and equilibrium

    If I have some arbitrary Thermodynamic system, and I want to find the equilibrium state what do I do? Lets say that I know Internal energy: U(S,V) Helmholtz free energy: F(T,V) Enthalpy: H(S,P) Gibbs free energy: G(T,P) (I omitted the dependence on particles N) I've been...
  41. P

    How Does an Ideal Rankine Cycle with Open Feedwater Heater Operate?

    Homework Statement consider an ideal rankine cycle with 1 open feedwater heater, the operates at a condenser pressure of 1inch of mercury absolute pressure and a turbine inlet pressure of 950psig and 850 deg F. The cycle produces turbine output power of 30MW. a)draw system diagram---done...
  42. Y

    Thermodynamic Problems: Work and Heat in a Thermodynamic Process

    Homework Statement Initially, 0.745 moles of an ideal gas in a container occupies a volume of 3.55 L at a pressure of 3.82 atm with an internal energy of 1705 J. The gas is then cooled at a constant volume until its pressure is 2.06 atm. Then the gas is allowed to expand at a constant pressure...
  43. J

    What Does the First Law of Thermodynamics Really Imply?

    1. One question ask "Which statement below regarding the First Law of Thermodynamics is best? Select the correct answer." One of the wrong answer is "A system can do work externally only if its internal energy decreases. " What does it mean do work externally? 2. Another question ask...
  44. O

    Euclidean QFT and thermodynamic analogy

    I have been wondering now for quite some time about the meaning of Euclidean Quantum Field Theory. The Wick rotation t\to it allows us to transform a QFT in Minkowski space to a QFT in Euclidean space (positive definite metric). After that the expectation values of observables can be...
  45. T

    A straight line thermodynamic transformation

    Hi, Homework Statement One mole of a diatomic ideal gas performs a transformation from an initial state for which the temp. and vol. are respectively 291K and 21000 cc, to a final state in which temp. and vol. are 305K and 12700cc - a straight line in the P,V diagram. Find work performed, and...
  46. W

    Solve Thermodynamic Homework: Methane Gas Heated 50% at 8MPa, 300K

    Homework Statement The question ask to find the final temperature of methane gas that is heated so that its volume increases by 50% using the ideal gas law, and the compressability. The initial conditions are temperature is 300K and pressure is 8MPa. The system is isobaric. Homework...
  47. B

    Exploring Absolute Zero - Thermodynamic Implications

    Hello all This question is probably a bit ridiculous, but here goes: Hypothetically, If any given closed system has obtained absolute zero temp, does any media (time, gravity, events)occur within? Thermodynamically, Wouldn't this be a state of infinite entropy? Can anyone describe such a...
  48. S

    Calculating Net Work, Heat Transfers in a Thermodynamic Cycle

    Homework Statement A gas within a piston-cylinder assembly undergoes a thermodynamic cycle consisting of three processes: Process 1-2: Constant volume, V_1=0.028m^3, U_2-U_1=26.4kJ Process 2-3: Expansion with pV=constant, U_3=U_2 Process 3-1: Constant pressure, p_2=1.4 bar, W_{31}=-10.5kJ...
  49. P

    Jet engine thermodynamic non sequitur.

    Hi all, This has been bugging me all day, so I thought I'd seek the help and advice of the internet. When a plane is stationary, you’d have to say that its jet engines are doing no useful work. The engines apply a static force on the airframe and could be said to be running at zero...
  50. C

    Thermodynamic Questions and Solutions for Steam and Gas Turbine Plants

    Homework Statement Can anyone help on the below? I have been working on this for days and still can't find the solutions?!? Homework Equations Steam ar 40 bar and 400C enters the high pressure turbine of a steam power plant at a rate of 20kg/s and explands to a pressure of 3 bar at...
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