Read about thermodynamics | 495 Discussions | Page 2

  1. WhiteWolf98

    Finding Isentropic Enthalpy, knowing Isentropic Entropy

    A short background: My question focuses solely on the part of the refrigeration cycle to do with the compressor, where the cycle begins. The first state is before the refrigerant enters the compressor, and the second state is after the refrigerant leaves the compressor. My goal is to obtain...
  2. C

    Is Specific impulse indicative of performance as a gun propellant?

    Black powder has specific impulse of around 80s, while rocket candy has up to 130s of specific impulse. Does that mean I could replace the propellant in a BP cartridge with 80/130 of the weight in rocket candy and obtain the same performance in an idealized gun? (as in without considering...
  3. WhiteWolf98

    Clausius-Clapeyron equation to estimate sublimation pressure of water

    Before this question, the questions were about the Clapeyron equation, and how to estimate ##\Delta s##. I'm completely put off by this question however, and don't know where to start. I've found that the triple point of water is at ##0.01°C##, and there is indeed data in the table for...
  4. K

    Gibbs' theorem and partial molar volume

    In the chemical engineering text of Smith, VanNess, and Abbott, there is a section on partial molar volume. It states that Gibbs theorem applies to any partial molar property with the exception of volume. Why is volume different? In other words, when evaluating the partial molar volume of a...
  5. S

    Temperature change brought about by radiation

    I tried modeling the problem quite a few ways. one was to say that the difference between the heat emitted by the room and the heat emitted by the bulbs would equal the heat absorbed by the room, and that could allow us to calculate temperature. This did not work. I'd appreciate your help
  6. P

    Calculate internal temperature and energy changes

    Question (These are incorrect values) Attempt I used and then found the respective change in temperature. However for the last question I have no idea, do I sum up the net change in temperature and use But then what is the work and how do we figure it out?
  7. Javier0289

    Thermodynamics - How to find an "adiabat"?

    I tried this... but I'm not sure if I'm doing it right or maybe there's a simpler way. Thanks for your time or help :) The fundamental relation is: $${S \over R} = {UV \over N} - {N^3 \over UV}$$ but I used $$s=S/N, u=U/N, v=V/N$$ to obtain $${s \over R} = uv - {1 \over uv}$$ then I did...
  8. Baibhab Bose

    Phase transition between two phases with different Cv

    I actually cant figure out what kind of phase transition it is and how to proceed through..!
  9. S

    How to calculate the transition temperature in this problem?

    Summary: The transition Sn(s, gray) ⇌ Sn(s, white) is in equilibrium at 18°C and 1 atm pressure. If ΔS = 8.811K mol for the transition at 18°C and if the densities are 5.75 g/cm3 for gray tin and 7.28 g/cm3 for white tin, calculate the transition temperature under 100 atm pressure The...
  10. S

    Changing the Air Temperature with a hair dryer

    Hi, so I found this on another old "AP" High School Finals Exam. I think I may be super lost. Because the only way that I can think about is KE = 3/2kT. And then that the difference of the Kinetic Energy of the air Particles is the Q supplied by the heater inside the air dryer. So ## \frac...
  11. P

    I The laws of thermodynamics and the Universe

    How would the first and second laws of thermodynamics apply to the creation and existence of the universe? I'm not a physicist (and unfortunately, do not remember a lot that I learnt in Physics class in school and college about Thermodynamics). I did some searching and I have come across an...
  12. JD_PM

    Heat engine undergoing an elliptical cycle

    An ideal diatomic gas undergoes an elliptic cyclic process characterized by the following points in a ##PV## diagram: $$(3/2P_1, V1)$$ $$(2P_1, (V1+V2)/2)$$ $$(3/2P_1, V2)$$ $$(P_1, (V1+V2)/2)$$ This system is used as a heat engine (converting the added heat into mechanical work). Evaluate...
  13. Parzeevahl

    Entropy change for water in contact with a reservoir

    Problem Statement: 1 kg of water at 273 K is brought into contact with a heat reservoir at 373 K. When the water has reached 373 K, what is the entropy change of the water, of the heat reservoir, and of the universe? Relevant Equations: dS=Cp*(dT/T)-nR*(dP/P) dS=Cv*(dT/T)+nR*(dV/V) I am...
  14. Rahulx084

    Questions about the Point Function (Thermodynamics)

    We know from first law of thermodynamics for a closed system that ##dE##=##\delta Q## -##\delta W## , my question is that for a closed adiabatic system net heat transfer =0 this mean net change in energy = work done , does that mean for an adiabatic system work done is a point function as...
  15. H

    I Calculate the number of states for a particle in a box

    The multiplicity of states for a particle in a box is proportional to the product of the volume of the box and the surface area of momentum space. $$ \Omega = V_{volume}V_{momentum}$$ The surface area in momentum space is given by the equation: $$p^{2}_{x}+ {p}^{2}_{y}+{p}^{2}_{z} =...
  16. E

    B Black holes and the first law of thermodynamics

    The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed. What happens to matter consumed by a black hole? What happens to it and where does it go? Does the first law still hold true?
  17. J

    Equating two formulas for root-mean-square velocity

    (a) My question : Are all the formulas correct? If so I can write ##v_{rms}## in form (2) and compare that result with the other velocities to get the answer (rms > average > most probable)
  18. J

    B Simple clarification regarding the sign convention for work

    Precursor : Sign conventions regarding Work by the system/on the system may even vary among Physics textbooks and among Chemistry textbooks and as a rule of thumb it is better to clearly mark out the convention used by the text being referred to specifically and remain consistent with it...
  19. Irene Jin

    Well-type manometer

    A well-type mercury manometer has a well of 0.02m^2 area and a tube of 40mm^2 area. The liquid has a density of 13,534 kg/m^3.Given that the tube is open to the atmosphere and the well is connected to the inert gas manometer was to measure: Calculate the pressure of the inert gas in kN/m^2 if...
  20. S

    A Review of modern non-equilibrium thermodynamics theories

    Looking for thorough serious comparative review of modern generalisations of classical non-equilibrium thermodynamics of continua. I have heard about several such generalisations: 1) rational mechanics by Truesdell, Coleman, Noll. 2) extended thermodynamics by Müller (and Ruggeri). 3) the...
  21. Quentin_Phys

    I Relationship between the Volume of a balloon and the time it takes to deflate

    I would like to ask a question on whether there is a proportionality between volume of a balloon, and the time it takes to deflate. I have conducted several balloon hovercraft experiments. I need to find the relationship between the amount of air pumped into the balloon and how long the...
  22. TheBigDig

    Efficiency of the Rankine Cycle

    WT, the work done by the turbines, as the difference in enthalpy from point 2 to point 3 WP, the work done by the pumps as the difference in enthalpy from point 4 to point 5 Q as the difference in enthalpy from point 3 to point 4 Taking these I get h5 = -252.3kJ/kg. However, my work ratio is...
  23. TheBigDig

    Efficiency of a steam power plant

    My inital assumption was to just take T1 = 5600 and T2= 300K, find the maximum efficiency and then divide it by two and three but I don't believe this question to be that simple. I'm confused as to where the 750K fits in as I thought no matter what occured in between the heat reservoir and heat...
  24. M

    Chemistry Molar solubility lab questions

    I’m confused on how to calculate molar solubility because I don’t see what’s the difference between that and Ksp.
  25. C

    Why is air in atmospheric pressure and room temperature a gas?

    This seems like a simple thermodynamics question but I would like clarification. So the absolute critical temperature is 132.5 K (-221.17 F) and the absolute critical pressure is 3.77Mpa (546.7 psi). I understand that for temperatures above the critical point, a pure substance undergoes an...
  26. Z

    Thermodynamics with use of Zusammenstand and probability

    Homework Statement Three-state system. The nucleus of the nitrogen isotope 14N acts, in some ways, like a spinning, oblate sphere of positive charge. The nucleus has a spin of lft and an equatorial bulge; the latter produces an electric quadrupole moment. Consider such a nucleus to be spatially...
  27. CharlieCW

    Thermodynamic identities

    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...
  28. T

    Simple thermo question: Is the pressure inside the balloon the same as the outside pressure?

    Homework Statement Homework Equations Ideal gas law The Attempt at a Solution The solution to this problem assumes the pressure inside the balloon is the same as the outside pressure, i.e. atmospheric pressure. Is this a valid assumption? I would guess otherwise.
  29. hnnhcmmngs

    Equation of state of a solid

    Homework Statement [/B] Find the equation of state of a solid that has an isobaric expansion coefficient dV/dT = 2cT - bp and an isothermal pressure-volume coefficient dV/dp = -bT (Assume the solid has a volume Vo at zero temperature and pressure. Enter a mathematical equation. Use any variable...
  30. A

    I Can the volume of a control volume change with time?

    Can an expanding balloon be considered a control volume?