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Thermodynamics - Science topic

Thermodynamics is the branch of natural science concerned with heat and its relation to other forms of energy and work.
Questions related to Thermodynamics
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If one uses a coordinate transformation, say t -> a t' +b_i x^i, does it change the thermodynamic quantities of a black hole, say entropy, temperature and others?
the general question is that: does coordinate transformation change the Smarr relation (the generalized form of the first law of black hole thermodynamics)?
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Mojtaba Shahbazi But you changed the vectors, so in this regard it's not the physical senses of thermodynamics and the various preservation laws, just the distributions of space and time. In another regard, the detectors only have amplification effects on the detections, not the 1:1 energy collisions with them :)
But philosophically, they don't change. What has changed is only our understandings, perceptions on the detections, and acceptance on the inexact methods of observational astronomy (or observational cosmology).
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Can absorption isotherms be used for gas-liquid absorption processes?
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In fact, it is actually a bit unusual that with regard to gas-liquid absorption, no names of scholars have been assigned to particular equilibrium curves and their corresponding mathematical functions, other than William Henry.
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Hi all,
To set things clearly: I am a PhD student working on the process implications of electryfing the ammonia production by replacing conventional SMR with Water Electrolysis. A part of my preliminary work is to assess the difference in theoretical minimum energy consumption. To do so, I have calculated a first approximation by summing up the reactions (SMR, Water gas shift, Haber-Bosch,...) and calculating the enthalpy of the resulting "total" reaction. I have done this for the "Water Electrolysis + Haber-Bosch scenario" and validated the minimum with values from the literature.
However, for the conventional "SMR + Haber-Bosch scenario", values from the literature are different. To be more specific, here is the energy minimum calculated in the following conference paper:
(...) the theoretical minimum of energy consumption for the process itself (represented by LHV of methane) is 22.2 GJ/t NH3 (...)
So here is my question: Why use the LHV of methane (instead the enthalpy of reactions) to calculate the energy minimum ? I feel like this is incorrect as I do not take into account the synthesis of methane.
Thanks in advance for any answers,
Antoine
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The paper you cited also includes the combustion of methane to provide the energy needed to account for the endothermic reaction as well as bringing the reaction temperature to that where the reaction occurs (850 C). For the combustion reaction, the LHV of methane is appropriate, where as for the SMR reaction, the heat of formation is appropriate. The reactor(s) consist of tubes packed with catalyst where the SMR, WGS, and HB reactions occur. On the outside of the tubes, CH4 is burned using either air or pure O2 to provide the energy needed for the process.
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One might argue: Animals increase their survivability by increasing the degrees of freedom available to them in interacting with their environment and other members of their species.
Right, wrong, or in between? Your views?
Are there articles discussing this?
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Also check please the following useful RG link:
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Can absorption isotherms be used for gas-liquid absorption processes?
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The specific surface area and pore distribution of any sample may be obtained from the measurement and analysis of the adsorption isotherm. The gases are always physically adsorbed on the solid surface at low temperatures in the atmosphere of adsorptive gases. According to the BET multilayer adsorption model, absorption isotherms be used for gas-liquid absorption processes.
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Looking for information on Microscopic Thermodynamics? Check out this repository of information and examples made available free on the Web by Professor Pohl, derived from his classic textbook, Microscopic Thermodynamics, by Irey, Ansari and Pohl, John Wiley and Sons, 1976, ISBN 0-471-42847-7. http://thermospokenhere.altervista.org/
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I am managing the site for Jim Pohl during the transition from www.thermospokenhere.com (paid) to thermospokenhere.altervista.org (freebie) so let me know if you find any broken links or things that don't work.
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Hello,
I have a vapor production device that provides me with air+steam flow of 80% or 40% w/w (volume ratio) water vapor quality at 100 degC. The flow passes through a series of valves and tubes where it cools down because of heat transfer. There, the temperature is measured to be something around 50deC. I know that at 50degC, this amount of water vapor corresponds to super-saturated flow. So, I assume that the extra water vapor has been condensed inside the tube, and the resulting flow is a saturated vapor (I don't have access to see how much water has been condensed). Do you find this assumption realistic? Or I may be dealing with a super-saturated flow?
On the other hand, I am a bit uncertain about the measurements of the temperature sensor. To what extent, do you think that latent heat of condensation on the sensor can affect the temperature reading?
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I don't understand your problem. Do you generate steam mixed with air at 100 C at above ambient pressure, or is it ambient pressure and you are sucking vacuum (since you have pressure drop in valves)? Anyway, there is no straight forward answer to the temp. reading. You may have measurement errors if the sensor is not properly insulated or calibrated, it may also be due to heat loss, since you have a significant amount of inert gas present. You should carefully check your measurement system before diving into speculations.
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Is that right? (From an article, Using graph theory to analyze biological networks.)
Things flow in biological systems: energy, nutrients, blood, air, as examples.
A graph is a set of points with connections.
A graph is like a photograph. Biological systems are like movies. If that analogy is valid (well, maybe it is not?), then graphs are not the optimal way to model biological system; it is necessary to also model flow.
Your views?
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The mathematical discipline which underpins the study of complex networks in biological and other applications is graph theory. It has been successfully applied to the study of biological network topology, from the global perspective of their scale-free, small world, hierarchical nature, to the zoomed-in view of interaction motifs, clusters and modules and the specific interactions between different biomolecules. The structure of biological networks proves to be far away from randomness but rather linked to function. Furthermore, the power of network topology analysis is limited, as it provides a static perspective of what is otherwise a highly dynamic system, such that additional tools should be combined with this approach in order to obtain a deeper understanding of cellular processes.
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I would like to know how to calculate the thermal power in kWth. Is it possible to convert it to kW or kWh or J? is 1kWth equivalent to 1kW? Because kWth is an additional SI power unit, I base it on the attached material, but I need more information on how to convert it from other units. Maybe it is a very basic and easy question, but I would be very grateful for any materials and explanations.
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Dear Professors,
Thank you very much for your help and explanations. I would like to know how to calculate this unit from another one (any equations, etc., eg. from kW to kWth or something similar, if possible).
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The general consensus about the brain and various neuroimaging studies suggest that brain states indicate variable entropy levels for different conditions. On the other hand, entropy is an increasing phenomenon in nature from the thermodynamical point of view and biological systems contradict this law for various reasons. This can be also thought of as the transformation of energy from one form to another. This situation makes me think about the possibility of the existence of distinct energy forms in the brain. Briefly, I would like to ask;
Could we find a representation for the different forms of energy rather than the classical power spectral approach? For example, useful energy, useless energy, reserved energy, and so on.
If you find my question ridiculous, please don't answer, I am just looking for some philosophical perspective on the nature of the brain.
Thanks in advance.
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Hi,
The mitochondrion in cells is a powerhouse of energy. There are some articles on the topics of your interest:
Jeffery KJ, Rovelli C. Transitions in Brain Evolution: Space, Time and Entropy. Trends Neurosci. 2020;43(7):467-474. doi:10.1016/j.tins.2020.04.008
Lynn CW, Cornblath EJ, Papadopoulos L, Bertolero MA, Bassett DS. Broken detailed balance and entropy production in the human brain. Proc Natl Acad Sci U S A. 2021;118(47):e2109889118. doi:10.1073/pnas.2109889118
Carhart-Harris RL. The entropic brain - revisited. Neuropharmacology. 2018;142:167-178. doi:10.1016/j.neuropharm.2018.03.010
Sen B, Chu SH, Parhi KK. Ranking Regions, Edges and Classifying Tasks in Functional Brain Graphs by Sub-Graph Entropy. Sci Rep. 2019;9(1):7628. Published 2019 May 20. doi:10.1038/s41598-019-44103-8
Tobore TO. On Energy Efficiency and the Brain's Resistance to Change: The Neurological Evolution of Dogmatism and Close-Mindedness. Psychol Rep. 2019;122(6):2406-2416. doi:10.1177/0033294118792670
Raichle ME, Gusnard DA. Appraising the brain's energy budget. Proc Natl Acad Sci U S A. 2002;99(16):10237-10239. doi:10.1073/pnas.172399499
Matafome P, Seiça R. The Role of Brain in Energy Balance. Adv Neurobiol. 2017;19:33-48. doi:10.1007/978-3-319-63260-5_2
Engl E, Attwell D. Non-signalling energy use in the brain. J Physiol. 2015;593(16):3417-3429. doi:10.1113/jphysiol.2014.282517
Kang J, Jeong SO, Pae C, Park HJ. Bayesian estimation of maximum entropy model for individualized energy landscape analysis of brain state dynamics. Hum Brain Mapp. 2021;42(11):3411-3428. doi:10.1002/hbm.25442
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I want to study the interdiffusion of Ni/Ti bilayer at 500 degrees. I have relaxed the interface and calculated the interfacial energy. My next step is to do MD simulation. Should I need to convert my Ni/Ti crystal bilayer to amorphous Ni/Ti bilayer (by heating at quenching) and then use a thermodynamic  ensemble to study the interfacial reaction and diffusion?
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If you melt and quench your structure, you will get the amorphous alloy of Ni/Ti instead of interface Ni/Ti. Depending on your objective, I suggest two things
1. If you wanna study the interfacial energy of Ni/Ti crystalline, you just need to do an MD simulation of Ni/Ti bilayer crystall at a certain temperature until the potential energy is convergent. Then, you need to extend the simulation and monitor the diffusion of the atoms.
2. If you wanna study the interfacial energy of amorphous Ni/Ti, you need a melt-quench of Ni and Ti to get amorphous Ni and amorphous Ti separately. Then, make the interface between Ni and Ti and did the same as number 1.
Best regards,
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Lee's disc apparatus is designed to finsd thermal conductivity of bad conductors. But I am having a doubt that, since soil having the following properties:
1. consists of irregular shaped aggregates
2. Non uniform distribution of particles
3. Presence of voids
Can we use Lee's disc method find thermal conductivity of soil???
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Replace the glass plate in the original Lee kit with a new plate made up of test soil. Run your experiment and have your readings accordingly. It should give accurate results.
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I'm going to work on a CHP system and I'll need to simulate it to calculate energy, exergy, exergyeconomic, and exergoenvironmental parameters (4E analysis). Previously, this was supposed to be done in the engineering equation solver (EES). But now, I'm looking for someone who has experience working with Thermoflow. Is it possible to calculate these parameters in Thermoflow?
Actually, I'll need to make an optimization (from the perspective of thermodynamics and economic factors). Is this possible to achieve them in Thermoflow instead of EES??
I'd appreciate your responses in advance.
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You can use other softwares like Cycle Tempo or Steag Ebsilon
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Dear Colleagues
I hope you are doing well. I want to calculate thermodynamic properties of ammonia and water mixture. A part of my simulation is shown below:
X=0.5294
Y=1-X
h = refpropm('h', 'T', 67.7+273.16, 'P', 116.92, 'water', 'ammonia', [Y X])
However, following error is shown:
Error using cell2mat (line 52)
CELL2MAT does not support cell arrays containing cell arrays or
objects.
Error in refpropm (line 318)
z_kg = cell2mat(varargin(nargin));
What should I do?
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You can create the mixture in the Refprop using the UI and then call the mixture in coolprop using the following line of code:
PropsSI('S', 'H', h, 'P', p, "REFPROP::y.mix").
Let me know if you need more details
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why emulsions are always thermodynamically unstable? how to solve this problem
A water-in-oil emulsion is prepared by homogenising 5 cm3 of water into 10 cm3 of dodecane containing surfactant. The average radius of the droplets is 12 m. Calculate the total oil-water interfacial area generated in the emulsion in SI units. State any assumptions you make.
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The statement that emulsions are always thermodynamically unstable is incorrect. Please read about the difference between unstable macroemulsions and stable microemulsions.
About your actual problem: I suppose this is an exercise to a lecture, right? Did your lecture say anything against simply calculating the area of a spherical droplet with the given radius and multiplying that with the number of droplets?
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1, The gas diffuses to vacuum,dq = 0, dS = dQ / T = 0,so the entropy in the
diffusion process cannot be calculated: S (T1).
2, If S (T1) has no physical meaning, then S (T0) and S (T1) have no physical
meaning.
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This is a screenshot from the scientific and technological literature. The theory of the second law of thermodynamics is inconsistent with the experiment, which is equivalent to the death penalty. As a result, many people are still there to make silly excuses.
Remember: This is not a case. There are many more examples.
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Good morning,
I would like to know if any of you has reviews or courses about this topic "isotopic exchange" ( Kinetics, Thermodynamics )?.
Thank you in advance!
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You find the isotopic exchange reaction H2 + D2 → 2 HD in several textbooks of statistical thermodynamics, for instance in T. L. Hill, “An Introduction to Statistical Thermodynamics”, Addison-Wesley 1960, Chapter 10-4. The book is admittedly old, but good, and the various contributions to the partition functions are well explained.
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Dear Colleagues,
I can't properly understand why VdP is not included in First Law of Thermodynamics.
If I add δQ amount of heat energy to a system, then some of this energy increases the internal energy U of the system. Internal energy means the kinetic energy of the gas particles ( For ideal Gas).
This is dU. Some part is used to do the external work. This is PdV. And some part is used to stored as pressure energy. This is VdP.
So, δQ = dU + PdV + VdP.
But VdP is not included in First law of thermodynamics.
Please help me to explain this confusion.
Thanks and Regards
N Das
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The first law of thermodynamics states that energy of a closed system changes due to energy transferred across the system boundary as heat or as work. Work is force times displacement, and this leads to dW = pdV (force F=p*A, displacement dx=dV/A where A is are). Vdp is NOT work, hence does not appear:
dU = dQ - dW = dQ - pdV
However, with enthalpy H=U+pV you get the alternative form
dH = dQ + Vdp
(but Vdp is not work, still).
See or any other textbook on TD for more detail.
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I used CPMD (with PBC) to perform MD with constraints at different values of a reaction coordinate, and the resulting free-energy profile, obtained after thermodynamical integration, does not appear smooth. The barrier seems OK but the product region, at large values of the reaction coordinate, exhibits oscillations. What could cause such artifacts?
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Varying acidity of the system may also effect
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The science of energy and work and health is important in chemistry and physics ,but it deals with health as many factors like food ,diet and disease ,how this is affect the health?
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The book on biochemistry will help you to see it better,
I would advise: Elliott W & Elliott D "Biochemistry and molecular biology" Oxford eds.
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Is there a computational or analytical method to calculate the corrosion resistance of a superalloy based on the composition of the alloy and thermodynamic parameters obtained by ThermoCalc?
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Dear Dr. Shubhansu Singh ,
I suggest you to have a look at the following, interesting paper:
- Determination of Al-2.18Mg-1.92Li Alloy’s Microstructure Degradation in Corrosive Environment
Franjo Kozina, Zdenka Zovko Brodarac, Sandra Brajčinović and Mitja Petrič
Crystals 2021, 11(4), 338; https://doi.org/10.3390/cryst11040338
My best regards, Pierluigi Traverso.
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Please, if anyone could clarify this question I received from one of the reviewers of my manuscript. What am I supposed to present?
"discuss the mechanism thermodynamically, where photo generated holes and electrons can be involved in the photocatalytic reaction."
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As a first guess at what is being required, I would suggest that they might be wanting to know the Carnot efficiency, or perhaps just the raw figure of the ratio of the usable energy that is obtained by the system divided by the total energy that was applied.
It's a bit of an old reference now, but personally, I would pick out my copy of
C.Mead and L.Conway (1980) "Introduction to VLSI Systems", Addison-Wesley, Reading, USA, ISBN 0-201-04358-0
where they have a chapter on thermodynamics, just to see if they mention anything that could be applicable in your own problem.
Let me know if you see how I might expand on any of the things I have said here.
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are can some models thermodynamics is not given the correct coordination of plait point in ternary system?with know are given good results tie-lines calcul. regards
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A very interesting topic, "quantification of randomness" in mathematics it is sometimes reffered to as "complex theory" (although it is more about pseudorandom than randomness) that is based on saying that a complicated series is more random and then there are tests for randomness in Statistics and perhaps the most intriguing test related to information theory -"entropy"(as also being of relevence to and result of second law of thermodynamics), while there are also random numbers generators (pseudorandom numbers generators) and true random numbers generators using quantum computing.
So, what I've been trying to, is making a complete list of all available algorithms or books or even random number generators that will allow me to tell me how much random a series is, allowing me to "quantify randomness".
There are 125 unique infinite series which are pseudorandom that I have discovered and generated based on a rule, now how do I test for randomness and quantify it? Uf the series is random or there is probably a pattern, or something that will allow me to predict the next number in the series given I don't know what the next number is.
Now, do anyone know of any github links based on any of the above? ^ (like anything related to quantifying randomness in general that you think will be helpful).
A book/books on quantifying randomness will be very very helpful too. Actually anything at all...
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You should check out seminal and fundamental work by Gregory Chaitin starting in 1965 when he was a student in CUNY (City Univ. of New York) and continuing through the 1970's.
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Theoretically speaking, when subsonic reactant flow passes through strong deflagration waves (strong expansion waves), the products must be in supersonic speed. But this is not possible because it violates the thermodynamics second law.
Can anyone please explain how?
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Hello Thomas Cuff,
Thanks for your reply.
I was going through Rankine-Hugoniot relations explained by Prof. S.R. Chakravarthy, from IIT Madras on YouTube.
There he explains this scenario.
He also mentioned this in the continuous video. Please check the timestamp 52:00 in the YouTube link (https://www.youtube.com/watch?v=TVVwiyRvXR8&list=PLbMVogVj5nJQDbg-ivB9ilWI9h3aJ78-y&index=25)
Then I tried to figure out why by going through Second Law, Gibbs free energy, Entropy relations.
In the process of doing so, I posted here for an expert's answer.
Thank you!
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Dear community,
I was modelling recently binary systems (such as 1-octanol/Nitrogen) at elevated pressure and temperature by PC-SAFT. The point where the bubble and dew point curves meet mark the mixture's critical point. Regarding a binary system the so called "critical locus" with different temperatures, pressures and compositions, connects the critical points of the pure components.
When determining the mixture's critical points (as shown in the attached figure) by PC-SAFT a sharp rise of bubble and dew point curves can be observed in the region where the mixture's critical point (for the regarded pressure) should be located.
Is there to your knowledge a physical reason for the observed phenomenon? Or is it solely to model inaccuraties in the range where the dew and bubble point curves merge?
With best and thanks in advance, Michael
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The diagram is probably wrong, or at least not precise. At a critical point of a mixture the slopes dT/dx and dT/dy should both be zero. Depending on the algorithm used for solving the equilibrium conditions, there may be problems particularly in the vicinity of critical states. Successive substitution methods, for instance, are known to be problematic, unless used with a convergence acceleration. Which method did you use?
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Arrow of time (e.g. entropy's arrow of time): Why does time have a direction? Why did the universe have such low entropy in the past, and time correlates with the universal (but not local) increase in entropy, from the past and to the future, according to the second law of thermodynamics? Is this phenomenon justified by the Gibbs law and the irreversible process?
With respect to all the answers, in my opinion, no answer to such questions is completely correct.
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An irreversible process in an isolated system is accompanied by an increase of the entropy of the system.
An irreversible process in a system in contact with its surroundings is accompanied by a decrease in the Gibbs energy of the system (and an increase in the entropy of the system+surroundings, which constitutes an isolated system).
Then, the Gibbs energy is a thermodynamic potential that arises naturally when considering systems in thermal and mechanical contact with their surroundings. The increase of the system+surroundings entropy is equivalent to the decrease of the Gibbs energy of the system.
Now, the connection between time and entropy is another issue.
The universe is expanding, and, therefore, the entropy is increasing globally. All proceses are inherently irreversible, and, therefore, entropy is increasing globally.
Time goes in one direction. Entropy goes (globally) in one direction (always increasing, though not always at the same rate). Then, should there necessarily be a connection between entropy and time?
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The second law of thermodynamics violates the epistemology of "internal causes determine external manifestations".
From the picture (book content), the second law of thermodynamics deduces: "the efficiency of Carnot heat engine has nothing to do with the thermophysical properties of working medium". This is absurd, like "human looks have nothing to do with genes"
"Carnot heat engine efficiency and human appearance" belong to external appearance, while "working medium thermophysical properties and genes" are internal causes. Internal causes determine external appearance.
Thermologists over consume "anti perpetual motion machine" and "irreversible". The second law of thermodynamics violates the rigor of science.
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I agree that the second law of thermodynamics cannot, and should not; merely be cited through dogma.
However, the implications are not as dramatic as you imply. The efficiency of Carnot heat engine is saying nothing more, or less, than that a body of gas contains moving components, and that we are trying to extract that movement (kinetic energy) into our device (a piston, for example) and that if we only transfer a proportion of the particles' energies (proportional to the temperature range of Thot down to Tambient) instead of the full amout (proportional to the temperature range of Thot down to Tabszero) then we are only extracting a fraction of the energy that we could (in theory) have extracted:
( Thot - Tambient ) / ( Thot - Tabszero )
Meanwhile, the overall second law of thermodynamics involves statistical measures, and is saying no more, or less, than saying that the sum of the faces of throwing two dice in a game of Monopoly has a mean value of 7, or that the number of radioactive atomic nuclei that decay during one half-life of the element is 50% of them.
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As part of my project, I plan to model the water-ammonia adsorption refrigeration cycle at EES. I acted according to the manual of EES, but unfortunately, I can not find the MASSFRACTION and QUALITY functions in the function info and in the Brines section. There is the ammonia-water mixture but the mentioned functions do not exist.
I read the link mentioned at the end, but unfortunately, I could not find them in my software version.
Thank you in advance for your help.
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It is interesting to note that there are analogies between economy and a thermodynamic framework. I have only begun to delve into this inter-connection. It looks like the thermodynamic analogy has not served very far. I have visited some lectures by Prof. Steve Keen. He emphasizes the importance of energy conversion in producing surplus in an economy. Labor and Capital are only means to achieve work from given resources. He is also of the view that macroeconomics can be formulated without any microscopic foundations. So that sounds thermodynamic, as a self-consistent framework, although we have a statistical foundations for thermodynamics. But also I am wondering if financial crises may be described as sort of phase transitions. And how to describe a stable economy as a steady state system? Any opinions or suggestions for interesting ideas, or the state of research in this direction, are welcome.
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Ramandeep S. Johal came acrss this link and this says it all
please do go thru the details and am sure might be of good help for your research as well
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Since V changes with changing P and T in high pressure you cant simply get a P-T curve for constant V.
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The rate of a chemical reaction is typically given by r = k[A][B] where [-] indicates concentration. However, it seems to make sense to use r = k{A}{B}, where {-} indicates activities, since the activity represents the effective concentration. I've found two papers that use this method for the hydration kinetics of carbon dioxide, with good results:
However, in the classic work on "Gas-liquid reactions", Danckwerts says the following:
"It is a mistake to suppose that, when the reactants are non-ideal solutes, thermodynamic activities should be substituted for concentrations in the rate-equation, and that the corresponding rate-constant will then be independent of composition. This formulation is misconceived in principle, and in practice the use of concentrations usually leads to somewhat better results that the use of activities"
I know the Danckwerts book is from 1970 and the papers above are from 2007 and 2010, but they knew their stuff back in the day! What has changed? Why is this formulation misconceived? And who is right?
Lastly, I know the rate equation is itself a simplification of the actual process, but if I want to get an accurate estimate, should I use concentrations or activities?
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At the risk of not adding a lot to the conversation and speculating about someone's thought process, an possibly being spectacularly wrong, I will point out the final bit of the Danckwerts quote has two parts: 1) This formulation is misconceived in principle and 2) and in practice the use of concentrations usually leads to somewhat better results that the use of activities. I would suggest that this second part may have been the key take-home point at the time. Given the state of computing, data availability, analytic techniques, etc. one would be better served by using the concentration approach. For part one, I must confess I don't quite follow why the term misconceived was used - the discussion of Dr. Geletii and others seems correct to me. Perhaps though the key is in the previous sentence which states that "the corresponding rate-constant will then be independent of composition" is the problem. That is, the point of concern isn't about the activities per se, but that the rate constant is found to variable (not constant) in that situation. Looking back to the second point, is this really saying that the activities of non-ideal solutions were inadequately being modeled?
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Statistical mechanics considering interaction is attached to the second law of thermodynamics. Considering the influence of temperature on the interaction potential, statistical mechanics can prove that the second law of thermodynamics is wrong.
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If you apply quantum mechanics consistently without using semi-classical approximations you get for the partition function
Z=\sum_n \exp -\beta E_n
with n running over all N-particle energy eigenstates of the system. The E-n are temperature independent and no conflict arises with the second law of thermodynamics. I assumed here that the system is confined within an external potential.
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I want to calculate thermodynamic properties, but in Gibbs2 calculations the temperature and pressure range selecte by default. I want to select it manually, please some one help me regarding my issue.
thank you.
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Please define your specific system of study ?
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Let's imagine a clean surface of stagnant Al-Mg-Ca melt. We know that surface-active elements such as Ca and Mg have a higher concentration in the surface layer. During my investigations, I have found out that there is a possible "lateral" difference of the concentration at the outmost surface layers of the melt. Meaning, the concentration of the Ca atoms is higher at some points of the surface compared to the nearby regions on the surface. How can this lateral difference in the composition be explained?
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We can imagine a clean surface but we know in reality, it will be covered by an oxide film. Therefore, when you observed these differences, the presence of an oxide layer can no longer be ignored. I suspect the reason for these differences can be attributed to the compositional variation along the surface oxide.
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i need the solution of thermodynamics of hydrocarbon reservoirs by dr.firoozabadi .especially chapter 2 & 3.
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Hi,
As far as I know, there is no problem-solving book.
You can get help from the professor or book resources
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I am looking for reasoned / reasonable explanations of the dynamic behavior of bulk and surface nanobubbles.
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I do get the full scenario you have in mind, but it sounds more like if you have mobilities reacting on driving forces like concentration gradients and interface curvature. In such a case diffusional fluxes related, at a given time, with a classical 1st Fick's law might imply a curvature dependent diffusion coefficient. Such a case I, however, would not interpret in terms of a curvature dependent diffusion coefficient, but instead (see above) in terms of a curvature- and concentration-gradient independent mobility which determine the fluxes.
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When depicting the melting curves of proteins, lots of DSC studies were done with samples containing molar-scale denaturants such as urea and GuHCl. However, if denaturants destroy the protein structure, shouldn't the experiments be focused on the native thermostability of proteins? Why can't native proteins be studied using DSC? I'm quite new to this area and would appreciate any opinions.
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You are right in some view. Indeed, At a high concentration of urea or guanidine hydrochloride in an aqueous solution, complete denaturation occurs, which in some cases is reversible after removal of the denaturing substance by dialysis. For a number of amino acids with functional groups in side radicals, surprises were observed, for example, poly (l-benzyl-β-histidine) in solutions containing small amounts of simple mineral acids takes on a disordered conformation, while in the presence of a stoichiometric amount of perchloric acid it exists in the form a -spirals. The answer to your question depends on which goal you are searching for.
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I need data on thermodynamic excess functions or vapour pressures or activity or activity coefficients of water - N-methylacetamide mixtures. I have searched but I can't find anything. Can someone give me a "hint".
Thank you very much and I hope you can help me.
Dr. Felipe Hernández-Luis
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Dear Felipe, many thanks for asking this interesting technical question. As a synthetic inorganic chemist I'm absolutely not an expert in this field. However, I came across two potentially useful literature references which might help you in your analysis. Please have a look at these articles:
Vapour + liquid equilibrium measurements and correlation of the ternary mixture (N-methylacetamide + ethanol + water) at the temperature 313.15 K
Hydrophobic Collapse in N-Methylacetamide–Water Mixtures
and
Temperature Dependence of Air−Water Partitioning of N-Methylated (C1 and C2) Fatty Acid Amides
Unfortunately none of these three papers have been posted as public full texts on RG. If they are of interest to you, you can easily contact the authors via RG and request the full texts of these papers.
I hope this helps. Good luck with your work!
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I am looking for appropriate research on the process of matching the turbocharger to marine diesel engines. If you know relevant references, books and articles in this field, I will appreciate introducing them to me. Thanks.
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Dear Amirreza Javaherian,
I hope the below-mentioned reference may help you.
Turbochargers
Marine Engines
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I am Looking for a Reaction or phase change material to Produce Heat From Ice to oprate the fuel cell in Sub-Zero temprature in Static conditon. to oprate AFC's it is needed to be heated up.
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Solvent extraction
Direct aqueous injection
Head space extraction
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Hello, I've been investigating a bunch of monomers which spontaneously react in water to form a polymer. I would like to know how to calculate the thermodynamics of such a system. On the surface, this seems like a straight-forward question, however, I've only seen implementations of thermodynamic integration, free energy perturbation, or umbrella sampling for the most part. Unfortunately, my system is not simply A + A = B, it's A + A + A + A + A + A(n) = B(n). i.e. it's 10 monomers linking together to form a single polymeric molecule. Now in TI, FEP, or US most implementations are simply atom 1 of molecule A and atom 2 of molecule B are constraint and bonded/broken. However, for a many reaction system, how much one achieve Gibbs energy and entropy? I would ideally like to compare the Gibbs energy of state 1 (only monomers in solvent) and state 2 (polymer in solvent). And then also look at solvation energy by obtaining state 3 (only solvent). Is there a way to obtain JUST the thermodynamics of a single set of trajectories or from a single simulation? Why do we need to use two separate simulations which are compared? How would I obtain G and S for my hypothetical system?
Thank you!
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- Calculation of DelG and Del S in AB initio complex .
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The second law of thermodynamics violates the basic definition of thermodynamics
1. The physical definition of thermodynamic efficiency can get the opposite conclusion of the second law of thermodynamics.
2. The second law of thermodynamics is really a low-level mistake.
3. See the figure below for details.
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From an excerpt from book by H B Callen, it is said that thermodynamics is time independent. Quantity energy is time independent. Can't figure out how it is time independent?
Attached image is from page number 6.
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I think Callen was not referring to any physical law in particular, but to the fact that in Equilibrium Thermodynamics no attention to time is paid (i.e., kinetic aspects are absent) and the time evolution in a given process is irrelevant. In fact, in Equilibrium Thermodynamics reversible processes are considered to be quasi-static processes taking an "infinite" time with infinitesimal changes in the thermodynamic variables, and equilibrium states are characterized by time-invariant thermodynamic variables. of course, that is an important idealization, but that formalism provides upper/lower bounds to energy changes/transformations for real processes.
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Inconel 738
temperature = 1200 °C
pressure = 10^(-8) atm
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one of the precise and useful method to calculate the activity at elevated temperatures is Knudsen Effusion Mass Spectrometry (KEMS), In this quantitative technique, a condensed phase is equilibrated with its vapor inside a Knudsen cell heated at high temperature for example up to 2500 K and under vacuum. The vapor phase is sampled under molecular regime and analyzed by mass spectrometry. The technique allows identifying all the molecules simultaneously present in a complex vapor and determining their individual partial pressure which can be measured in the range 10-12 up to 10-4 atm.
Inside a Knudsen cell, the thermodynamic equilibrium imposes that the activity in the condensed phase ai equals the activity in the gas phase. the spectrometer links the partial pressure pi of a species i and activity, and activity can be calculated by :
ai=(gamma)i * Xi= Pi/P0i
A high level overview of this technique can be found in Drowart et al at :
10.1351/pac200577040683
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Globally, the phenomenon interpretations of the sign of: the standard Gibb′s free energy (ΔG°), the standard enthalpy (ΔH°) and the standard entropy (ΔS°) are the same in different publications.
Nevertheless, when the amount of the absolute value of one thermodynamic parameter is enough high or low, we read some small differences of interpretations, especially when there are some specific phenomenon, or adsorbent, or adsorbate, or metallic ions, etc…
The goal of this discussion is to help researchers in this field to enrich their interpretations in new experimental data by reading our different answers and replies on different situations already published.
Another delicate point which can enrich this discussion is that if one thermodynamic parameter varies slightly with temperature, how to affect the usual interpretations (the increase or decrease) for the case of positive or negative values?
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The thermodynamic parameters that were applied to different systems are the Gibb′s free energy (ΔG°), the enthalpy (ΔH°) and the entropy (ΔS°). The Gibb′s free energy would indicate if the process is spontaneous (ΔG°< 0), if the process is non-spontaneous (ΔG° > 0) or if the process is at equilibrium (ΔG°= 0). The enthalpy would indicate if the process is endothermic (ΔH° > 0) or exothermic (ΔH° < 0). Furthermore, the absolute value of the enthalpy would indicate if the process is chemisorptions (80 <ΔH° < 200kJ/mol) or physisorption (ΔH° <80kJ/mol), while the entropy would indicate the degree of disorderliness of the studied process which is possible (ΔS° > 0) or not possible (ΔS°< 0).
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What is the best free program to calculate quantum-chemical molecular descriptors, such as the total electronic energy, energies of the highest occupied and lowest unoccupied molecular orbital, and absolute electronegativity? And, for thermodynamic descriptors, like, standard Gibbs free energy and enthalpy?
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Different files formats issued from quantum calculations (Gamess, Orca, NWChem, PSI4 etc .. are free) can be used for performing different analysis as you cited. I could suggest you to have a look on the incredible Multiwfn program. Also, for thermodynamic, you might be interested in KistHelp:
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Hi dear researchers
I would like to use MATLAB in order to optimization of thermodynamic cycles. I know that Refprop software can provide properties of the material. But the free version of that software dose not work appropriately. Do you have access to active version of software to share file of it with me ,please? I really need for it.
Regards
Amir
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Use this syntax. I will work as well as Refpropm without anything else.
h = Props( 'H' , 'P' , 101.3 , 'T' , 298 , 'water' )
You just need to download the file that I attached here and put it in the same folder as the Matlab code is.
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Should exergy analysis be taught to undergrad engineering students? I am wondering to what extent I should include this in my undergrad Thermodynamics course for 3rd year chemical engineering students? We do energy balance and the entropy balance already.
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Dear Isabella.
Exergy is very complex CONCEPT. Actually, exergy is the limiting (highest or lowest) value of energy that can be useful in a thermodynamic process, taking into account the restrictions imposed by the laws of thermodynamics.
That is, exergy is the maximum work that a macroscopic system can perform during a quasi-static transition from a given initial state to a state of equilibrium with the environment. In other words, this is the minimum work that must be spent on the quasi-static transition of the system from the state of equilibrium with the environment to a given initial state.
Unlike energy, exergy is not a parameter of the state of the system, but a parameter of the process. Comparison of the exergy of an ideal quasi-static process with the energy of a real nonequilibrium process shows the degree of perfection of a real thermodynamic process.
Therefore, I believe that it is the topic for the postgraduate, certainly.
V. Dimitrov,
Professor (Emeritus) in Chemical Physics.
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I am trying to implement the thermodynamic model of ejector assisted compressed air energy storage (CAES) and I need thermodynamic properties of Therminol 66 thermal oil. In the reference paper, I am following, the author utilized Refprop 9.1, but I can seems to find the the Fluid "therminol 66" in the Refprop fluid library. Does it have any other name in the Refprop library?. If anyone has any idea please guide.
Thank You
Reference Article:
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Hayder Ibrahim Mohammed Norbert Lümmen Thank you for cooperation, I found the properties using coolProp.
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Hello
Kindly refer the free energy functional for systems with elements A-B and A-B-C, in the attached image.
My question is, why the gradient of the dependent element (A) appears in multi-component system (2), while not considered in binary system (1)? It would be also better if you attach any references for derivation of (2).
Thank you!
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Dear Viswanathan Ramamoorthy, considering the sum constraint, that you also show in the image, the gradient energies in the ternary alloy are not independent, i.e., this can be just written such for A, B and C but only two of these three gradient terms are independent. If you check the corresponding evolution equations for concentration fields, this must become clear: dC_A/dt + dC_B/dt + dC_C/dt = 0.
The source of gradient energies is the spatially asymmetric interactions between the atoms/solutes in a given gradient. If you like to understand the true physical origin of it, I suggest you look into these derivations
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when a system say a heat engine draws heat from a hot reservoir (body at high temperature compared to the system) it does work, since heat is a low grade energy not all of heat is converted to work, therefore remaining heat is released into a cold reservoir (say to the environment, which is at lower temperature compered to the system's temperature). Now, this released heat (which is unavailable for the system) is somehow related to the entropy of the system, according to some literatures. My Question here is how is this heat related to Entropy?
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In classical thermodynamics, entropy is defined as energy that is unavailable to generate mechanical work as given by Clausius. Entropy within classical thermodynamics represents the absolute law that is always true.
Boltzmann changed forever our understanding of entropy as he discovered that entropy is defined as a statistical distribution which relates a given macrostate to associated microstates. In his theory, it had been shown that entropy can change both ways.
Sometimes even in an isolated system entropy can spontaneously decrease, see the paper bellow for details.
This is possible due to the statistical distribution of velocities of gas in a chamber. To make work in a heat machine you need to go from one distribution to the other one, velocities becomes lower. As take energy from the system distribution is shifting to lower values and it becomes harder and harder to take energy from it, until you reach the temperature of the surrounding bath. The terminal energy has a corresponding distribution that is associated with the specific temperature.
I recommend reading the following historically chronological description of entropy notion evolution. Please, remember that Boltzmann's theory of entropy forever changed physics: proposed atomism & proved it, defined an arising of statistics from movements of perfectly defined deterministic particles!
***
When you want to read a bit longer version, explained in depth, that is about five pages long including pictures, then it would be interesting to read the section on entropy of the following paper:
I do recommend reading citations of papers and books given in this methodic paper. There is a lot of very important information hidden in it.
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The question arises from complex systems theory, in which I faced a contradiction, as earlier I thought the equilibrium state of a system means maximum order. The obstacle in my way is thermodynamics. Please help me to better understand and potentially solve this contradiction.
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Your question is fundamental in the proper understanding of a complex system. It is in detail answers in the paper
A brief explanation follows. The entropy of the constant system where everything achieves the same state is equal to zero following the equation
S = p * ln (p) where p = 1 .
In the other hand, the maximum entropy is achieved by the white noise where each state has the same probability to occur.
S = Sum_i (p_i * ln(p_i)) for p_i = const .
For N bins in the distribution you get p_i = 1/N.
S = N * (1/N * ln(1/N)) for 1/N = const .
It gives S = ln(1/N) .
The maximum entropy for given number N of bins is equal to the logarithm of 1/N.
The operational complex system is having entropy S lower that the maximum one. White noise is useless.
More details, examples, and citations are given in the shared paper. This aspect of complex systems is really fascinating.
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Hello,
I need to find experimental data for CO2 solubility in water that can be simply modeled by using the Peng Robinson equation of state for a project. The concentration of CO2 has to be very low for this purpose. I wonder if you could suggest to me a research article that contains the described experimental data for my project?
Best wishes
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I would look in physicochemical handbooks. It is a popular and well-described gas in terms of physicochemical properties.
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Water kept in a CLOSED Container at 20 degree Celsius will have a vapor pressure of 2.34 KPa, this vapor pressure is also called as saturation pressure (for pure liquids). Which means 20 degree Celsius is the saturation temperature. It is found in literatures that vapour and liquid are in equilibrium at this point. In that case we can call LIQUID water as saturated liquid and the vapours corresponding to it as saturated vapour. But when we look it from boiling phenomenon prospective, then water below 100 degree Celsius at 1 atm pressure is called as subcooled liquid. So can we call water at 20 degree celsius as subcooled liquid as well as saturated liquid??
PS I would like to request you to give me a simple explanation so that I can understand it easily.
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Water kept at 20 degree Celsius in a closed container might be called as saturated water.
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There is a closed system containing water at 20 deg. Celsius having pressure above it 0.1 mega pascal. Now this system is heated at constant pressure. Now according to some literatures, the temperature of the water rises till 99.6 deg. celsius. At this temperature the liquid will start vaporizing and liquid at this stage is called as saturated liquid. The vapour phase is called saturated vapour. Saturated vapour and liquid co-exist in equilibrium. The temperature and pressure at which phase change occur and liquid and vapour are at equilibrium are called saturation temperature and pressure. The temperature and pr. remains constant till all the liquid gets converted to vapour.
Now I have 2 questions, i) while we heat water, and temperature rises from 20 deg. Celsius, will there be no vapor formation till 99.6 deg. Celsius?
ii) If there is phase equilibrium in the system at 99.6 deg. Celsius and 0.1 mPa, How can it be possible that all of liquid water gets converted into vapour at some point?
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Adrian Velazquez-Campoy even in the close system if the temperature is below 99.6 (for example 50oC), why does the water evaporate? Why the molecular goes to the gas phase?
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A high grade energy can be completely converted into a low grade energy, however visa versa is not possible for a spontaneous process. Since PE can be converted into KE but KE cannot be converted into PE when the process is spontaneous. Therefore should we consider KE is a higher grade energy like work and electrical energy?
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Heat - Low grade energy since it can be converted into work .
Electrical and Chemical Energy - High grade energy - concentrated on small space can be converted into high amount of work .
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Sodium decahydrate is Na2CO3.10H2O which is obtained by dissolving sodium carbonate in water and then crystallizing it. So can be consider it as a mixture (i.e. an impure substance) or is it a compound (pure substance)?
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Dear
Na2 CO3 in water can be considered as 2 Na(+) and CO3 (-2). Na (+) ions have no chemical reaction with water, although oxygen atoms in H2O molecules are attracted by Na(+). The CO3(-2) make a dominant reversible reaction with water: CO3 (2-) + H2O ⇌ HCO3 (-) + OH (-)
Further reaction of the HCO3 (1-) ion with H2O would be negligible. Thus, dissolving Na2CO3 in water is a physical reaction.
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In what case would a reaction rate always show direct relation with activation energy or would it always be an inverse relation? Is it a indirect relation, inverse relation or both case can hold? (Please provide supporting resource, thank you).
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Toyese Oyegoke when we are talking about your question and particularly the catalyst which always lowers the energy of the transition state for the reaction - in this case any reaction you can assume.The difference between the transition state energy and the other part that is the reactant energy is the main ACTIVATION ENERGY and this is very important to understand, Lowering of this energy which means lowering of transition state energy also ensures and lowers the activation energy for sure
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Hello Everyone,
I am a beginner in using REFPROP software by NIST. I am trying estimate various thermodynamic properties of carbon dioxide using GERG and other equations of state. I am wondering, why I am observing a significant difference between the results of GERG-2008 and AGA8 model. Specifically the difference is in the enthalpy, entropy and internal energy.
For an example, please see the REFPROP results in the attached file. It can be seen that GERG-2008 is yielding negative and completely different values as compared to Peng-Robinson and AGA8 models. What is the reason of that variation?? How to get the similar results for comparison?
Note: I used the default reference state by REFPROP.
Regards,
Mujtaba
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This problem is mostly caused by the second law of thermodynamics. My other paper reflects this confusion.
The following figure shows the deviation between NIST data(IAPWS97) and experimental data.
IAPWS97-----Iapws97 is the most precise result made by thermophysicists all over the world with the second law of thermodynamics. The results are not consistent with the experiment. The problem lies in the second law of thermodynamics.
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The reactions are as below:
CO2=CO+1/2O2
H2O=H2+1/2O2
These reactions are from syngas production.
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Study the Ellingham diagram for the reactions. This tells you that CO formation is favored over CO2 in high temperatures.
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It is meant especially thermodynamic and gas-dynamic state.
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Thank you for participating in the discussion.
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Is there any code available to calculate Spin Spin Spatial correlation function in 1d Ising model?
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Hello. I wrote a code for this . i can share it with you
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MgO + 2NaOH → Mg(OH)2 + Na2O
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I suppose Ben Mannaerts gave the complete answer.
Best regards
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Evolution violates the second law of thermodynamics ?. The law states that "the entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium". In other words, an isolated system's entropy (a measure of the dispersal of energy in a physical system so that it is not available to do mechanical work) will tend to increase or stay the same, not decrease. Creationists argue that evolution violates this physical law by requiring an increase in order (i.e., a decrease in entropy).
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Absolutely not applicable! :)
the law is for closed systems while evolution is for open (living) systems with important supplimentary energy supply!
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Hi!
I have a protein system where a single water molecule can play a role in a ligand stabilization. To check whether this single water molecule is important in binding, I wanted to perform TI (thermodynamics integration) calculations, starting from system with water and annihilate it. My plan was to use AMBER software (PMEMD) for this purpose. I would replace water molecule with dummy atoms during TI. After many trials I finally got my tleap output (parmtop & prmcrd), but while running the script I am getting an error.
My question is: am I doing it right or there is a simpler way than TI to calculate an impact on energy after cutting our water molecule from the system?
I will be grateful for any tips!
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  • The total amount of energy released when a positron and an electron annihilate is 1.022 MeV, corresponding to the combined rest mass energies of the positron and electron. The energy is released in the form of photons.
  • The amount of energy (E) produced by annihilation is equal to the mass (m) that disappears multiplied by the square of the speed of light in a vacuum (c)—i.e., E = mc2.
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It is becoming apparent that the configurational entropy bears no relationship with the stabilization of the so-called "high-entropy alloys" (or HEAs). I wonder if we should suppress the term "high-entropy" from these novel class of alloys and then, use the "highly-concentrated alloys" term instead.
Any ideas and/or recommendations?
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The term "high-entropy alloys", although widely accepted in the literature, is misleading. It is a fact that the maximum possible configurational entropy of equimolar alloys increases as the number of components increases, but so does that of a bag which have the same number of balls of many colors as the number of colors increase (in fact, it increases in the same way as in the alloy). Nobody, however, would be crazy to ascribe any thermodynamic effect to a bag of colored balls. What potentially has an effect is the exchange of entropy with a reservoir, and this effect is very weak. The HEAs, however, are not to be dismissed as a unicorn (something beautiful, but non-existent). A stabilization effect indeed exists and this may be useful in technology. What I suspect is that what we are observing is the very complex thermodynamics of concentrated alloys, from which almost all thermodynamics textbooks I know warn us to stay away. So, using "highly concentrated alloys" since this is what they are. A collegue in the CALPHAD community suggested using simply "multicomponent alloys", but this is insufficient, since all technical alloys we use are multicomponent alloys.
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How to compute physical properties (thermodynamic parameters like free energy and kinetic parameters like rate) at different pH using computational software?
Suggestions of software/open source codes that can handle the problem is highly appreciated.
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It is a quite gross question ! . You should be more precise about your physico-chemical experiment . For eg HBZ distribution with variation of enthalpy / K1/K2 -ratio determination of ester hydrolysis at different acid concentration ( pH ) you can collect your dataset . With the specific equation modelling you can somply execute FORTRAN90 , C, C++ - https://www.researchgate.net/post/FORTRAN_vs_C_a_comperative_approach
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Hello everyone. I hope everything is well. I read the article which is attached with this question. I have a question about thermodynamic studies. The enthalpy and entropy is calculated according to equation 4 in this paper by using linear equation in fig 10. I use 8.314 as gas constant in this equation. But I obtained different enthalpy and entropy. I do not know why this happens. Please help me find my mistakes.
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Hi, I obtained enthalpy is 21.094 kJ and entropy is -94.185 J/mol
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It is a difficult task for me to translate my work into English, below is a try, it involves some deep topics.
Tackling a Century Mystery: Entropy (2008)
Introduction
Why are we still unable to explain the difficulties caused by a physical concept even after more than 150 years of hard work?
It is a very important milestone in the history of science to introduce the concept of entropy into physics, it was the first time to introduce one-way direction of change into the theory of science, and express irreversibility as the internal property of change. The introduction of the concept of entropy has had an extremely profound impact on the basic view of how science should understand existence and evolution of nature.
However, the introduction of the concept of entropy has also brought serious puzzles into physics, since the heat Q is not a state variable, it is really confusing to define a state function by the aid of a path differential and an inequality. To be exact, in 1854, R.Clausius has only given a symbol without any explanation to the physical meaning of the function S, classical thermodynamics itself cannot explain clearly what entropy is, it can only talking about how the entropy will change.
This is a very strange result difficult to be explain, because the concept of entropy does not seem like to involve the cognitive limits of science in our time, no one can understand what this state function is from classical literatures or any thermodynamic textbook but can only know how the state function will change, is this a perfect result?
The understanding to the entropy today we have mainly come from Boltzmann's statistical theory, in the entropy theorem, Boltzmann pointed out that entropy is proportional to the logarithm of thermodynamic probability, in H theorem, the second law was described to be the state change of thermodynamic probability, this later developed into a very popular view: entropy is a measure of disorder.
Until now, Boltzmann's statistical theory still faces a series of problems, the postulate of equal a priori probability is not applicable to the case when there are interactions within a system, such as multi-phase coexistence in thermodynamic equilibrium, liquid-liquid equilibria in a partially miscible binary system, or the segregation of alloying elements in a solid solution, and the temperature of nuclear spin system, the ordered state of Gibbs free energy, or the gravitational potential energy are some other examples. A very fact is that the postulate of equal a priori probability is not applicable to describe the ordered state of the particle distribution or the energy level distribution, this postulate is only applicable to the case when thermal motion is stronger than interactions. It is quite clear that thermodynamics does not need to consider this postulate, thus, how can one prove that Boltzmann's entropy is exactly equivalent to thermodynamic entropy?
What is puzzling is that we already know that we cannot discuss the second law when ignored the dissipation factors such as friction and viscosity, we also know that these dissipation factors are obviously related to the interactions but not the result of the postulate of equal a priori probability. Whereas, in statistical theory, near independent subsystems or statistical ensemble are the main models to discuss the entropy and the second law, in such ideological system, how can we discuss the dissipation factors such as friction and viscosity?
H theorem have been stumped by the ‘’inversion paradox’’ proposed by J.Loshimidt in 1876, it is also unable to explain the ‘’circular paradox’’ proposed by E.Zermelo based on Poincare recurrence theorem. Boltzmann himself later realized that the H-quantity model as a solution to explain the irreversibility derived from dynamics still has problems that are difficult to explain, it is only a phenomenological model, just as K.R.Poper said: ‘’Boltzmann failed to clarify the state of H theorem, nor did he explain clearly the increase in entropy’’.[1]
Another problem is: since there has been no monotonous function similar to thermodynamic entropy in dynamics, the general mathematical properties of the fundamental laws of dynamics (inversion symmetry) indicate that the dynamic "changes" are reversible. The explanation of the state of thermodynamic probability further revealed the contradictory that the description about the direction of changes and time in thermodynamics and dynamics are different. Since the explanation of thermodynamic probability cannot be applied to describe the direction of microscopic state change, this means that there will be no irreversibility in dynamics in the sense of the second law. This leads to the conflict between the two theoretical systems on the view of nature, in physics, we have been unable to establish the relations on the concepts of the direction of changes and time between dynamics and thermodynamics, the former describes to us a world without evolution, and the latter expresses the evolution as the unfolding of the second law.
Physicists usually regard Boltzmann's statistical theory as a scheme to establish the connection from the dynamics of the basic process to the thermodynamics of the statistical system, but this scheme has not been able to give complete results, and its scope of application has always been ambiguous. The description given by statistical probability shows the view that there is no microscopic explanation of entropy and irreversibility at the basic dynamics level. In this sense, Boltzmann approach leads to a complete separation between basic dynamic process and statistical collective behavior in the description on the direction of change and time, this doesn't seem like a real image of the world around us, for example, we can feel the existence of one-way direction of change from the beep of a radioactive decay counter, but this is not the unidirectionality expressed by Boltzmann's statistical theory, we also can hardly understand how to deduce the irreversible and non-deterministic theory from the reversible and deterministic dynamics.
From the 1850s to the present, in the following 150 years, the contradictory issues concerning the physical meaning of entropy and the different descriptions in the direction of change and time between dynamics and thermodynamics have become one of the core problems in the views of existence and evolution. Since the unidirectionality revealed by the second law of thermodynamics involves the direction of change and the meaning of time, this issue is related to our basic views on existence and evolution of nature. Many scientists believe that the second law is an approximate result, however, though a series of appeasement explanations have been given, the initial problems have never changed in more than 150 years, we still have to repeat the problem again and again that has aroused strong feelings over the past 150 years:
What is entropy?
What are the irreversible changes taking place?
[1] Not the original text.
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delS ( Universe ) = delS ( System ) + delS ( Surroundings ) - The creation of Universe ie a great chaos !! / Entropy . The universal entropy is related to Thermodynamic probability ( Theory of Creation ) - TOE - All about randomness .
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Since that second law of thermodynamics has a very special role in all branches of science, this law has been established with different approaches and formulations. Although Carnot introduced the irreversible process as well as irreversibility concept, Clausius formulated the second law of classical thermodynamics inspired by them as well as introducing entropy quantity for thermodynamical cycles. Clausius formulation defines thermodynamical entropy as a time direction for all physical processes. In fact, entropy and its significance are becoming an important challenge between scientists. Also, general branches of physics define entropy with general approaches that using them, the second law of classical thermodynamics can be extracted. In all these general approaches, energy and, generally energy levels have the main role for extracting the second law of thermodynamics.
Is the supposition of the unified field theory compatible with the Second Law of Thermodynamics?
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UFT - The theory of everything - Very interesting part of second law of thermodynamics ie entropy of universe = ultimate driving force ( UDF ) or thermo probability of creation of atomic / subatomic particles also a function of entropy .https://physics.stackexchange.com/questions/43582/do-laws-of-thermodynamics-have-a-place-in-theory-of-everything .
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I performed constrained MD in CP2K, and I obtained the average force along the reaction coordinate by averaging Lagrange multipliers using the script provided. Now, I require a free energy profile. It is evident that thermodynamic integration needs to be performed. I was wondering if there is any script or software to plot the same?
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I got python inbuilt function to do numerical intergration
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Carnot efficiency can be calculated by the first and second laws of thermodynamics. Which one would you like to choose?
See the following article for details
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