Thermodynamic Definition and 459 Threads

Dear experts, Considering a cylinder and a piston where the volume is V and the pressure is P and the temperature being T, the gas is slowly allowed to expand accepting heat keeping the temperature constant at T to twice the volume. The pressure according to the ideal gas equation should go...

Hi All, I have review my thermodynamic notes (~35 year ago..), and I could not able to restore how to get thermodynamic properties (u,h,s,v ..) for compressed liquids. I have found properties tables for compressed liquids ( for water..) but unfortunately the data starts at 5MPa. What if I look...

I was studying statistical mechanics when I came to know about the Boltzmann's entropy relation, ##S = k_B\ln Ω##. The book mentions ##Ω## as the 'thermodynamic probability'. But, even after reading, I can't understand what it means. I know that in a set of ##Ω_0## different accessible states...

Since the assignment asks the work done by the gas, that should be equal to P1*(V2-V1) aka the area under the P1 line. Do I have to subtract the work done to the system or is this the solution already? If so, why do I need P2?

Hi, I was revisiting my (high school level) understanding of thermodynamic cycles and I think I still have some doubts. Last year and more recently I posted a few questions which surely helped me, but I think I need more clarifications. In a nutshell, what I'd like to know is the following...

In thermodynamics limit, does function of many mean values(of some physical quantities) equal mean value of the function of the values?

dG= -SdT + VdP ... now dividing by dV holding temperature constant (dG/dV)T = -S (dT/dV)T + V (dP/dV)T ... now dT and constant temperature cancel out final answer: (dG/dV)T = V (dP/dV)T

If you take a system with fixed entropy S0 and let it evolve, it reachs equilibrium. Let Ueq be the energy of the system at equilibrium. Now take the same system with fixed energy U=Ueq (S is not fixed anymore), how do you know that the equilibrium reached is the same as before, that means with...

I've seen a thread posted on another forum which described a thermodynamic situation that captured my interest, so I though I would introduce a challenge problem on it. The other forum was not able to adequately specify or address how to approach a problem like this. I know how to solve this...

In process of releasing heat of nuclear reaction and burning oil, the internal energy of the material(that be burned) be contant if we prevent heat transfer to environment.The temperature of the material increase.How is entropy of the material varied(if we keep volume be constant)?If the entropy...

A coal fired steam plant takes in feed water at a temperature of 70°C and produces 15 tonnes of steam per hour at a pressure of 60 bar and temperature 400°C. The fuel consumption rate is 1.5 tonnes per hour and the calorific value of the fuel is 40MJkgˉ¹. Determine the power rating of the boiler...

assume I have 3 systems a,b and c. the equilibrium between a and c can be described by the equality PcVc = f(A1,..., An) and the same for b and c - PcVc = g(B1,...,Bk). why does the equality g(B1,..., Bk) = f(A1,..., An) describes an equilibrium between A and B? the 0th law states that if A and...

Mass = 0.12kg Initial temp = 500°c = 773K Initial pressure = 0.8 MPa = 800,000 Pa Final volume = 90L R = 287 Jkg^-1K^-1 1) Initial Volume V=mRT/P 0.12 x 287 x 773 / 800,000 = 26,662.12m^3 2) Final Pressure P2 = P1P2^1.2/V2^1.2 800,000 x 26,662.12^1.2 / 90 = 1,816,095,330 Pa = 1,816 MPa 3)...

Hi, consider an adiabatic irreversible process carrying a thermodynamic system from initial state A to final state B: this process is accompanied by a positive change in system entropy (call it ##S_g##). Then consider a reversible process between the same initial and final system state. Such...

I have a heat & mass balance diagram wherein there is a shell and tube heat exchanger to recover heat from hot exhaust gas using cold water. The exhaust gas inlet temperature is 120°C and the outlet is at 40°C. The inlet water temperature is 35°C while the outlet water temperature is at 50°C...

Help! Hi, I need in the secodn law of thermodynamic, we have the ENTROPY "S". Well, I need help for this: We have dS ≈ dQ Then we have dS = λ *dQ where we have λ = λ (T, ... ) I have to demostrate that : λ = 1/T , where T = temperature. Thanks for the advices and help!

Homework Statement Let x, y and z satisfy the state function ##f(x, y, z) = 0## and let ##w## be a function of only two of these variables. Show the following identities: $$\left(\frac{\partial x}{\partial y}\right )_w \left(\frac{\partial y}{\partial z}\right )_w =\left(\frac{\partial...

What are the precise conditions for thermodynamic equilibrium? I know that a system in thermodynamic equilibrium must have constant temperature and that there can be no net macroscopic flow of energy or matter. However, is it possible for there to be a system in equilibrium that has a spatially...

Are all arrows of time special cases of the thermodynamic one? The arrows of time I am referring to are the psychological arrow of time and the cosmological arrow of time. Thanks.

In thermodynamics, what is the relationship between the terms, "pressure–volume work", "mechanical work", "non-mechanical work", "∫pdV", and "-∫Vdp"?

Homework Statement I am always confused about how to correctly write the functions U, H, F, G when they're not depending on the usual variables p, V, T, S - same question for Q and W. For example, we have to calculate the temperature variation of a small surface of water when we isentropically...

Homework Statement An air parcel is investigated to study the weather.It rises up and rests at an equilibrium height in the atmosphere,where its weight is exactly balanced by the upward buoyant force. We shall assume ideal gas law to hold for all processes and neglect the mass of the air...

Hi guys, I have two questions as follows, ofcourse they may seem too basic, I have read through certain texts (engineering) but I still haven't been able to actually physically understand, so asked here 1) Whats thermodynamic pressure w.r.t physical point of view? - for a gas from...

Homework Statement n moles of gas, that follow van der Waals equation are to be employed as the auxiliary system in a circular cycle(parameterized using T_h and T_c as shown on the TS diagram. Calculate the efficiency of the cycle. Homework Equations , , Q = TdS The Attempt at a Solution...

Hello! I am a high school student and I would need some guidance regarding a thermodynamics book. I am reading and solving through these three: 1.Resnick,Halliday and Walker 2.University Physics- Young and Freedman 3.An introduction to mechanics-Kleppner and Kolenkow(purely for mechanics) Based...

In case of Otto cycle we consider that heat is immediately added to air fuel mixture(i.e constant volume heat addition) but in case of diesel cycle we consider heat addition at constant pressure and we also talk of cutoff ratios.why so??

Homework Statement The isobaric expansion coefficient and the isothermal compressibility are given by: $$\alpha_p = (1/V)(\partial V/\partial T)_p \quad \kappa_T = -(1/V)(\partial V / \partial p)_T$$ Suppose they have experimentally been determined to be: $$ \alpha_p = \frac{1}{T} +...

Homework Statement Box divided by a partition into two equal compartments containing ideal gas. Each compartment is having volume V ,temp T and pressure P 1.entropy of the system when the partition is given? 2.entropy of the system when the partition is removed. [/B]Homework EquationsThe...

I have a problem where I want to find out the static pressure over a city in a water pipe system. As I know the elevations over the city I was first thinking of just using p = rho * g * h, but this should only apply if the pipe system were under water (if I use the density of water at least). So...

I have to calculate the efficiency of the above cycle for an ideal gas, that goes at the order a-b-c-a: I know that the answer is 16/97 but I can't calculate the heat in the a-b stage.

Homework Statement :[/B] An astronaut visiting Jupiter’s satellite Europa leaves a canister of 1.20 mol of nitrogen gas 28.0 g/mol^2 at 25.0°C on the satellite’s surface. Europa has no significant atmosphere, and the acceleration due to gravity at its surface is 1.30 m/s2. The canister springs a...

Hi there. Earlier today I decided to pull out ice cream from the freezer. It is a magnum-type ice-cream and comes in a plastic wrapper. Once I opened the wrapper and removed the ice cream, I left the wrapper on the kitchen table and noticed something rather bizzarre (to me at least)...

How can I calculate thermodynamic property like entropy and enthalpy of 70% steam and 30% air mixture ?( at about 90 degree Celsius and 10 MPa)

Hello Everyone This question is motivated by a small calculation I am doing on polarization of bodies in external electric field. What I wanted to do is this: 1) Mesh the region 2) Prescribe uniform (and non-changing) positive charge distribution 3) Prescribe (initially) uniform negative...

Homework Statement Hi, So I have a perfectly insulated rectangular plate and I trying to use the 2D heat equation in conjunction with numerical finite diference methods and MATLAB to see how the temperature changes throughout the plate. My issue is with the heat source. I am supposed to decide...

Homework Statement A pump is used to move water through a pipe of diameter 150mm, Figure below. The water has a temperature of 20 Celsius and an absolute pressure of 100KPa. The pump moves the water up a vertical distance of 2m and the water exists at atmospheric pressure. Q1) Assuming the...

Homework Statement A non-conducting piston of mass m and area of cross section A is placed on a non-conducting cylinder. Intial height of piston is h and spring is relaxed with a spring constant k.Then,work done in displacing pistin by heating gas is (x is the displacement of the pistion)...

Homework Statement Homework EquationsThe Attempt at a Solution The work done is maximum in the path (3) as the area covered by this path is maximum. Now, dU = dQ + dW, the work done is minimum in the Path (1) , so dQ should be maximum. Hence, the correct options are A and C. Is this correct?

Homework Statement The saturation temperature is given in the parentheses. then what is Sat. on the Temperature column? Homework EquationsThe Attempt at a Solution

This is for research purposes. I am aware that first derivatives in thermodynamics always occur (a no-brainer). Do second derivatives occur in thermodynamics commonly as well?

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...

Homework Statement Homework Equations Thermodynamic Identity The Attempt at a Solution While I was able to work out the problem with the help of the hint, I couldn't completely understand the implication of said hint. The hint suggests that the equations for Chemical Potential in a process...

Homework Statement Homework Equations ##dS = \frac{1}{T} (dU - PdV)## assuming dN = 0 The Attempt at a Solution I have actually managed to solve all 4 parts correctly, except for the fact that I solved Part d) with the Sackur-Tetrode equation rather than the thermodynamic identity. I...

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...

Homework Statement The molar energy of a monatomic gas that obeys van der Waals' equation is given by E=\frac{3}{2}RT - \frac{a}{V} where V is the molar volume at temperature T and a is a constant. Initially, one mole of such a gas is at temperature T_1 and occupies a volume V_1. The gas is...

I'm a high school student with basic knowledge about thermodynamics. I have always come across systems under going reversible cyclic processes. Are there any cases for irreversible cyclic processes? Thanks in advance.

2. PV^y = const, y=Cp/Cv, PV=nRT, 3. I've drawn the cycle for part a) of the question, but I'm not sure how to do part b). I know I need to relate Vm and 4Vo using the PV^y = constant relation but I'm stuck as to how to do it.

Hi. I'm reading a solution to a problem concerning a gas of photons. In the solution, the energy of the gas is given as E=2\sum_{\vec{k}} \frac{\displaystyle \epsilon_{\vec{k}}}{\displaystyle \exp[\beta\epsilon_{\vec{k}}]+1} where \epsilon_{\vec{k}} is one photon's energy. It is said then...

Homework Statement Consider a model thermodynamic assembly in which the allowed (nondegenerate) states have energies 0, ε, 2ε, 3ε.The assembly has four distinguishable (localized) particles and a total energy U = 6ε. Tabulate the nine possible distributions of the four particles among the...

This is more of a recurring conceptual doubt that I keep on running into when solving thermodynamics problems. We are taught that variations between extensive state variables in equilibrium are given by the following 'fundamental formula': dE = TdS + \mathbf{J}\cdot{d}\mathbf{x} +...