What is Thermodynamics: Definition and 1000 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.

View More On Wikipedia.org
  1. K

    Correct statement of 2nd law of thermodynamics?

    Thermodynamics is stated in different ways. E.g. In isolated systems entropy never decreases Heat never spontaneously pass from colder to warmer body Total energy quality decreases in all processes. Energy disperses But what is it exactly? What is the correct description of the 2nd law of...
  2. S

    Thermodynamics - Temperature change of Argon

    Homework Statement The temperature of n = 19 mol of argon gas is increased from T1 = 21 oC by Q = 4.4 kJ heat transfer, while the gas pressure is kept constant. What is the new gas temperature in Celsius degrees? Homework Equations and as its a monoatomic gas I think this means that the...
  3. M

    Problem set with air conditioners and thermodynamics

    Homework Statement You're in Paris, working on your first novel and short on cash. The owner of the cabaret downstairs has offered to take care of your rent if you'll help her design a climate control system for the place. It gets too hot and damp in the summer, and too cold and dry in the...
  4. J

    Unsure Regarding Temperature Model for an Open System

    Hi guys, I am currently working on my master thesis. I am supposed to make a dynamic model for a gas system and have some trouble setting up the energy balance. I am a noob when it comes to uploading pictures, so I don't have a figure for this, but let's consider a general control volume (CV)...
  5. V

    Thermodynamics Final Temperature of Water

    Homework Statement A certain mass of water in a copper pot is heated over a stove that releases joules of heat to heat the water. Later the same mass of water in an aluminum pot is heated over another stove that releases the same amount of heat in order to heat the water. Then the water in...
  6. H

    Calculating entropy for an adiabatic system

    Homework Statement A container of 1.5 Kg of gas is at a temperature and pressure of 293 K and 1 bar respectively. The gas is adiabatically compressed until its temperature and pressure are 450 K, 4.49 bars. Adiabatic processes are processes with no heat transfer. The properties of this...
  7. M

    Cooking (Thermodynamics) Problems

    Homework Statement 1. You are cooking a meal in your kitchen and have just put a pot of frozen soup on the stove to defrost. You turn on the burner and, when you ignite the gaseous fuel (methane or propane), there is a dramatic increase in the gas's thermal energy. Where did that thermal...
  8. T

    Pressure caused by beam of molecular oxygen

    Homework Statement A beam of molecular oxygen containing 1010 molecules/cm3 and average speed of 500 m/s strikes (elastic collision) a plate at an angle of 30º with the normal direction. Calculate the exerted pressure on the plate. Homework Equations P = Impluse x Flux The Attempt at a...
  9. Matt James

    Thermodynamics: Calculating Pressure Increase From Work

    Homework Statement Estimate the pressure increase required to impart 1 J of mechanical work in reversibly compressing 1 mol of silver at room temperature. What pressure rise would be required to impart 1 J of work to 1 mol of alumina at room temperature? For alumina take the molar volume to be...
  10. patrickmoloney

    Optimizing Refrigerator Efficiency: Solving for Necessary Power Draw

    Homework Statement Suppose that heat leaks into your kitchen refrigerator at an average rate of 300W. Assuming ideal operation, how much power must it draw from the wall. Homework Equations \eta = \dfrac{T_C}{T_H - T_C} W= \dfrac{Q}{COP} The Attempt at a Solution A typical refrigerator...
  11. W

    Thermodynamics: Comment on mistake

    Homework Statement Suppose you have a mole of water at 25##^{\circ}## at atmospheric pressure. You then raise its temperature to 30##^{\circ}##. Determine the change in Gibbs free energy. To compensate for the change, once can raise the pressure on water, how much pressure you need to increase...
  12. S

    Thermodynamics problem -- Steam cooled until it is just dry saturated

    "HOMEWORK" PROBLEM ORIGINALLY POSTED IN WRONG FORUM, SO NO TEMPLATE a rigid vessel of volume 1m^3 contains steam at 25 bar and 450c the vessel is cooled until the steam is just dry saturated calculate the mass in the vessel the final pressure and the heat rejected during the process? i know i...
  13. S

    No sublimation for human body in vacuum? [Thermodynamics]

    In my Thermodynamics course, we recently learned about the saturation pressure and saturation temperature of different substances -mainly water. As you know, the saturation temperature at which a substance begins to boil is specific to a fixed saturation pressure. Water only boils at 100...
  14. patrickmoloney

    Relation between heat capacities and van der Waals equation

    Homework Statement Find the expression for c_p - c_v for a van-der-waals gas, with the equation of state \Bigg{(}p+\dfrac{a}{V^2}\Bigg{)}(V-b)=RT Homework EquationsThe Attempt at a Solution Basically I've proved c_p - c_v = \Bigg{[} p + \Bigg{(}\dfrac{\partial E}{\partial V}\Bigg{)}_T...
  15. W

    Thermodynamics: Free Energy Confusion

    Homework Statement Hi all, I'm having quite a big problem trying to understand the concept of enthalpy and free energy. I feel that a good way to sort this out is to write out what I understand about these things and have people correct me. Thanks in advance for any assistance. I'm learning...
  16. S

    Thank you for your response AM. I appreciate it and will work through the steps.

    Homework Statement [/B] A four-stroke petrol engine with a compression ratio of 9 has a total swept volume of 2.71 litres distributed over 4 cylinders. Assume the corresponding ideal thermodynamic cycle and the following conditions to calculate the maximum amount of fuel which can be safely...
  17. F

    Thermodynamics, isothermal irreversible

    Homework Statement Can you please show how to solve this question (I am not asking it for homework. I am asking because it would help me understand better). Determine the entropy change in sys, surr, uni, when a sample of helium has of mass M grams at 298K and 1 bar doubles its volume in...
  18. G

    Help on a thermodynamics problem -- Power from a steam turbine

    Homework Statement Homework Equations P=F*V, dU=Q-W?, W=m(h1-h2) The Attempt at a Solution I have the initial conditions and final conditions written out. For W=m(h1-h2), I have W=9.48(h1-h2). I am having problems with the h values, which can be found in the steam tables.
  19. patrickmoloney

    Molar latent heat of phosphine

    Homework Statement [/B] Phospine exist in three forms. known as the \alpha, \beta and \gamma forms. The \alpha and \beta forms are in equilibrium with each other at 49.43 \, K, and the \alpha and \gamma forms are in equilibrium at 30.29 \, K. Obtain the molar heat of transformation for the...
  20. EastWindBreaks

    What is u in the equation for delta U=m(u2-u1)?

    Homework Statement Homework EquationsThe Attempt at a Solution U is internal energy, but what is u? if its internal energy at a specific state, then why its multiplied by mass? does not makes sense to me...
  21. F

    Question about the Hamiltonian and the third law of thermodynamics

    The third law of quantum mechanics states that a system at absolute zero temperature has zero entropy. Entropy can be conceived as an expression of the number of possible microstates that can produce an identical macrostate. At zero entropy, there should be exactly *one* microstate configuration...
  22. patrickmoloney

    Show that the entropy is non-negative

    Homework Statement Two vessels A and B each contain N molecules of the same perfect monatomic gas. Initially, the two vessels are thermally isolated from each other, with the two gases at the same pressure P and at temperatures T_A and T_B. The two vessels are now brought into thermal contact...
  23. I

    Residence time of SO2 in the atmosphere

    Homework Statement Use the IPCC estimate of anthropogenic SO2 emissions of 55 ⋅ 109 kg/year and natural SO2 emissions of 15 ⋅ 109 kg/year to estimate the residence time of SO2 in the atmosphere. Is the residence time consistent with SO2 emissions being able to travel from Ohio to Maine as...
  24. J

    Thermodynamics help in finding Temp, Volume and Pressure

    Hey Guys! I need some help for solving question 2 of this example as my HSC exam is in 5 days and I want to be able to solve this question if I receive it on the paper. Question: Graph: Answer for Q1 (Just the formula) : Work I have done towards this question: I have realized that from...
  25. J

    Pressure, Volume, and Temperature at a Point in a Thermodynamic Cycle

    Homework Statement Question: https://imgur.com/a/8rUw1 Graph: https://imgur.com/a/Z1oBO Homework Equations Answer for Q1 (Just the formula) : https://imgur.com/a/uesqN The Attempt at a Solution I have realized that from 1-2, there is an increase in pressure, decrease in volume and increase...
  26. yecko

    Why Does Enthalpy Change Differ from Heat Change at Constant Pressure?

    Homework Statement Homework Equations when constant pressure, h=w+u and so H=W+U=Q when U=E. However, in this question, when constant pressure, Q(=12750kJ)=W+U =/= H[=m(h2-h1)]. The Attempt at a Solution [/B] here's my calculation of enthalpy...
  27. patrickmoloney

    Why can the efficiency of a refrigerator (heat pump) be greater than one?

    In a heat engine thermal energy is converted into mechanic energy. In a heat pump or refrigeration cycle - fluid is being circulated between hot and cold wells. But how can the efficiency be greater than 1? Is it because COP_{\text{heating}}>COP_{\text{cooling}}
  28. R

    How to calculate percentage of water vapour that condenses?

    Homework Statement 1kg of moist air of RH 70% at 21oC is cooled at a constant pressure of 1 bar to 5oC. The vapour pressure at 21oC and 5oC are 0.025 bar and 0.0087 bar. The percentage of water vapour that condenses into water at 5oC is? Want to check whether my intuition & logic are correct...
  29. K

    Why Does the Chain Rule in Thermodynamics Include a Negative Sign?

    I'm trying to understand why $$\left(\frac{\partial P}{\partial T}\right)_V = -\left(\frac{\partial P}{\partial V}\right)_T \left(\frac{\partial V}{\partial T}\right)_P$$ where does the minus sign come from?
  30. H

    Exact thermodynamics equation of state

    Dear all, I am using molecular dynamics to calculate energy for ionic liquid. In the article that is proposed equation of state that I want to use, the author would call the energy in the following formula(u) conformational(potential energy): (du/dv)T + T(dp/dT)V = ptot Firt T and V are...
  31. C

    Watts transferred to water?

    My colleague has been developing a hybrid water/forced air heat transfer system for a prototype lighting solution we are developing. I am struggling to get my head around the calculations required to figure out exactly how many watts of energy (heat in this case) are being transferred to the...
  32. R

    Mathematics necessary for Radiometry, Photometry, Thermodynamics

    What are the math concepts I have to learn for Radiometry, Photometry and Thermodynamics (all Calculus-based) as applied in building science (engineering, architecture, etc.). I'm almost done with Multivariable Calculus and I'm aware that MV Calculus is necessary, but what specific calculus...
  33. Z

    Is Your Steam Saturated or Superheated?

    hi guys can you tell, how to know if steam is saturated or superheated?
  34. N

    Thermodynamics equivalence between entropy in two ensembles

    So while practicing statistical mechanics problems I was faced with the following problem : calculate the entropy as function of energy for an ensemble of harmonic oscillators ( the Hamiltonian is ##\sum_{i=1}^N \frac {p_i^2} {2m} + \frac {m\cdot\omega\cdot q_i^2} 2##) ). Now the official...
  35. P

    Reversibility in thermodynamics

    Conceptually, why does infinitesimally changing a system allow for a process to be reversible. For example, if we heat a system at temperature T1 to T2 by using a heat reservoir at T2, it is considered irreversible, but if we heat the system with many reservoirs at temperatures T1+dT, T1+2dT...
  36. Muthumanimaran

    What is the Maximum Temperature for a Copper Block at 1000 atm Pressure?

    Homework Statement (a) A block of copper at a pressure of 1 atm and a temperature of 5 degree celcuis is kept at constant volume. If the temperature is raised to 10 degree celcius what will be the final pressure? (b) If the vessel holding the block of copper has a negligibly small thermal...
  37. M

    Graduate level two phase flow boiling textbook

    I am looking for a graduate level textbook that would sufficiently describe the two phase flow characteristics during flow boiling. What textbook could I use to explore this topic? Is a graduate level forced convection going to cover two phase flow?
  38. E

    Thermodynamics: Water Properties

    Homework Statement Two pans filled with water. Water in a 3.7cm deep pan is observed to boil at 98 degrees Celcius. At what temperature will the water in a 46.3cm deep pan boil? Homework Equations P=3.146T-211.87 (linear approximation) Water properties table: 95°C 84.609kPa .001060 vf 1.9808vg...
  39. C

    Thermodynamics Ice Melting Question

    Homework Statement On a hot summer day, you planned a trip to a beach, but you inadvertently took a wrong turn and now you’re worried the ice in your cooler is going to melt. The cooler is 0.5 m × 0.5 m × 0.4 m, and is made with 5 cm thick Styrofoam (k = 0.033 W/m2K). Help your panicking...
  40. R

    Learning Radiometry, Photometry, Optics, Thermodynamics, ....

    Learning Radiometry, Photometry, Optics, Thermodynamics, Fluid Mechanics(Statics & Dynamics) with great resources. I'm looking for resources for understanding the topics above. I prefer video tutorials as opposed to books but I couldn't find any video resources on Photometry and Radiometry (I...
  41. H

    Finding the equations of state via the fundamental relation

    Homework Statement Homework Equations $$\frac{\partial S}{\partial u}\Bigr|_{v} = \frac{1}{T}$$ $$\frac{\partial S}{\partial v}\Bigr|_{u} = \frac{-P}{T}$$[/B] The Attempt at a Solution a.) $$\frac{S}{R} = \frac{UV}{N} - \frac{N^3}{UV}$$ $$\frac{S}{R} = \frac{UV}{N} - \frac{N}{uv}$$ $$...
  42. yecko

    Introduction to thermodynamics question

    Homework Statement In the image, as the first chapter of thermodynamics class, I understand all things in the answer except the highlighted part (lower bottom of the image). It is not directly related to thermodynamics but about the area ratio of the two ends of the tube, but I do not...
  43. Pushoam

    Self-Studying Thermal Physics: Seeking Recommended Books with Answers"

    I am self -studying "blundell thermal physics" . But,the answers of the problems are not given in the book. So, can anyone recommend me other book with the answers? I will be thankful to you for this. Will "An Introduction to Thermal Physics by Daniel V. Schroeder" be a better option ?
  44. RJLiberator

    Thermodynamics of a Constant Volume Gas Thermometer

    Homework Statement A constant volume gas thermometer contains a gas whose equation of state is (p+\frac{a}{V^2_m})(V_m-b)=RT and another, of identical construction, contains a different gas which obeys the ideal gas law, pV_m = RT. The thermometers are calibrated at the ice and steam points...
  45. D

    Intro Physics Need a good Thermodynamics book for science olympiad

    My event description is "Create a device that retains heat prior to the event and answer thermodynamics questions". This is a high school to 1st year college level competition. I just need a textbook with the basic information on Thermodynamics as well as some information on insulation and the...
  46. S

    Thermodynamics Hydrogen question

    1.The problem statement: Hydrogen (H2) is at standard conditions in a closed tank, V = 5l, and then it's cooled down for 55K. Find delta U and Q. 2. Questions: If it says standard conditions, can I just use pV = nRT to find n and then deltaU = j/2*nR(delta)T? Also, is there any work that a gas...
  47. H

    Experimental thermodynamics properties

    Hello everybody, I am using an equation of state to calculate the thermodynamical properties of a material. I have a problem which is the ideal part of the equation. Actually, I cannot be sure that the ideal contribution in my equation is the really ideal contribution, so I decided to calculate...
  48. L

    What is the Effect of Isothermal Movement on Internal Energy of a Gas?

    Homework Statement The dot in Fig. 19-18b represents the initial state of a gas, and the isotherm through the dot divides the p-V diagram into regions 1 and 2. For the following processes, determine whether the change Eint in the internal energy of the gas is positive, negative, or zero: (a)...
  49. M

    Where Should I try to learn more about thermodynamics and physics?

    Hi, I am a senior in high school and I want to learn more about thermodynamics and physics in general. Unfortunately, I don't have anything available at my high school. I am trying to find online courses but I honestly don't know where to look at because some of the courses I've seen seem too...
  50. W

    Cp & Cv Values: Example Problem 11.1 Explained

    Hello, I tried attempting the following example problem 11.1(please see below), however I don't quite get from where they got cp=1.00 and cv=0.717? I know that Q=m*cp*delta T=> cp=Q/(m*delta T) Q=n*cv*delta T=>cv=Q/(n*deltaT) Problem statement Their solution: How did they...
Back
Top