Thermodynamics Definition and 1000 Threads

Homework Statement The total pressure of a mixture of oxygen and hydrogen is 1.00 atm. The mixture is ignited and the water produced is removed. The remaining gas is pure hydrogen and exerts a pressure of 0.34 atm when measured in the same volume and at the same temperature as the original...

I have a thermodynamics question I'm having difficulty with... I have a steam generator heated by a 39MW nuclear reactor that powers two 4.5MW turbine generators. It produces dry saturated steam at 330psig, and enters the turbine at those conditions. It exits the turbine to a condenser...

Hi guys, 42 year old engine hobbyist here, not a student. I've had great luck figuring out my questions in this portion of the forum in the past and look forward to your input. Keep in mind that I'm not formally educated, so if it's possible to dumb something down a bit I'd appreciate it.1...

Homework Statement A cylinder fitted with a frictionless piston contains 5.0×10-4m3 of an ideal gas at a pressure of 1.0×105 Pa and temperature of 300K. The gas is then (i) heated at constant pressure to 450K, and then (ii) cooled at constant volume to the original temperature of 300K. The...

Ecosystems are open systems, they receive solar energy and other materials from outside the ecosystem and migration of animals is also witnessed. I read Physics uptil class XII and have done a bit of research on google books and have come across these three books: 1.Towards a Thermodynamic...

Homework Statement Homework Equations Q1 + Q2 = 0 The Attempt at a Solution I found the mass of water needed to cool the lava to a solid. I'm not sure how to find the rate of water needed to stop the lava...

Homework Statement Calculate the vapor pressure of water at 25°C, based on the Gibbs free energy when vaporising from liquid water to vapor (so at 1 atm and 25°C ). Homework EquationsThe Attempt at a Solution After integrating d g/d p= RT/p. I get my formula p = p0*exp (-delta gm(p0, T)/RT). I...

Hi guys, I was watching an episode of stargate and I got this idea, I've been trying to explain to myself. It has to do with time dilation and the first law of thermodynamics. So here it is. Imagine a small time dilation field, a small sphere or something, with an accelerated time. A simple...

I have been trying to determine the efficiency of an ideal Otto cycle based on the compression ratio of my car and the heat of combustion of gasoline and I think I'm not entierly wrong but there is something quite off. When trying to calculate the temperature of the combustion stage my result...

I'm trying to build a heat treating oven/kiln and I'm having a difficult time identifying equations to assist in sizing and insulation. I have info on sizing a heating element based on available power and I have and equation to quantify heat transfer through the walls and insulation but I'm...

Homework Statement Initially you have mW = 4.6 kg of water at TW = 74°C in an insulated container. You add ice at TI = -19°C to the container and the mix reaches a final, equilibrium temperature of Tf = 33°C. The specific heats of ice and water are cI = 2.10×103 J/(kg⋅°C) and cW = 4.19×103...

I was wondering all the assumptions I need to make regarding a design for a heat exchanger and cooling tower design from a IC engine testbed. Each engines average output is 55kW and the water jacket temperature is 80 degrees (C) and has to be cooled to 65 degrees (C). The ambient atmospheric...

Hi, I need help I got a project for school about jet engines. They say bysubstitution of equations 5.1, 5.2, 5.5 and 5.6 butI don't know the steps how i get t0 the last formule. Thank you Maximilian Popelier

Homework Statement You have 1.0kg of ice at 0.0 deg C in a pot on a stove that produces 900 W of power. Assuming that the pot and the stove are 'perfect' (i.e., no heat lost) and ignoring the heat capacity of the pot, compute the time it will take for this ice to boil away completely...

Hi, I am trying to understand which thermodynamics process or processes could model a vacuum engine (mostly known by the name "flamelickers") and similar engines.. In a vacuum engine you have a cylinder and piston system that draws hot air from a heat source, cools it and mechanical work is...

Hello, Few years back I was reading about calculating multiplicity using hypercube (n-cube). Multiplicity was normalized using this method. I wanted to read it again but I just cannot find it now. I tried every combination of keywords. I remember it was a Wikipedia link. Any help would be...

A diabatic process is defined as follows: Rapidly changing conditions prevent the system from adapting its configuration during the process, hence the spatial probability density remains unchanged. Typically there is no eigenstate of the final Hamiltonian with the same functional form as the...

Hello Pf's members Suppose we isolated a methane's molecule at a room with 213 kelvin. According to second law, methane's molecule tends to break it's bond for reaching whole system (methane's molecule and surroundings) to maximum entropy. On the other hand for breaking these bonds we need...

I have a brayton refrigeration cycle with a regeneator same as the picture below only with irreversible regenrator, compressor and turbine (And different values). The given in my problem are: Ti=0 C, T3= 35 C, T5= -80 C, mass flow rate m= 0.4 kg/s Turbine efficiency Et=0.85, Compressor...

1. Given the following p-V diagram of an ideal Stirling Cycle, determine the theoretical values of W12, Q12, W34 and Q34 in terms of T1, T2, V1, V2, n (the number of moles) and R (the universal gas constant). Determine the total theoretical p-V work W12341 for the full cycle.2. dU = dQ-Pdv3...

1.Recently, we performed an experiment to measure the efficiency of the Stirling Engine. The experimental method can be seen in the image provided. We have been asked to calculate the power dissipation PR and the energy dissipation per cycle WR as part of our lab report. The other variables...

I am going to learn an introductory to thermodynamics in my chemistry book(Senior year) so I thought I could ask some questions here about it to confirm my understanding: 1) Temperature: I have seen a lot of discussions here about what temperature really is. I came up with a summary (Thanks to...

Homework Statement The figure below shows a combined cycle formed by a gas turbine and an organic Rankine bottoming cycle. Steady-state operating data are labeled on the figure. Owing to internal irreversibilities, the generator electricity output is 95% of the input shaft power. The...

Homework Statement An isolated box contains two chambers separated by a thermally insulating but moveable partition. Both chambers contain dilute gas (same kind) at different densities and temperatures. The left chamber contains 1.0 x 10^22 particles at 25 degrees celsius and the right chamber...

Why if a hot object did not emit radiation then second law of thermodynamics would be violated?

Homework Statement This is question 2.18 from Bowley and Sanchez, "Introductory Statistical Mechanics" . Show with the help of Maxwell's Relations that $$T dS = C_v dT + T (\frac{\partial P}{\partial T})_V dV$$ and $$TdS = C_p dT - T( \frac{\partial V}{\partial T})_P dP.$$ Then, prove that...

Homework Statement An inventor claims to have invented four engines, each of which operates between constant-temperature reservoirs at 400 and 300 K. Data on each engine, per cycle of operation, can be found in the table below. Of the first and second laws of thermodynamics, which (if either)...

Homework Statement Two moles of a monatomic ideal gas are at a temperature of 300K. The gas expands reversibly and isothermally to twice its original volume. Calculate the work done by the gas, the heat supplied and the change in internal energy. So: T = 300K; ΔT = 0 n = 2; R = 8.314 J K-1...

Homework Statement figure: http://www.chegg.com/homework-help/questions-and-answers/dot-figure-represents-initial-state-gas-isotherm-dot-divides-p-v-diagram-regions-1-2-follo-q5905441 The dot in Figure (b) represents the initial state of a gas, and the isotherm through the dot divides the p-V...

Hi, In a standard converging-diverging rocket nozzle, we have (ex.) the relation:(1-M^2)\frac{dV}{V}=-\frac{dA}{A}By substituting in definitions, we can obtain\left(1-\frac{V^2}{\gamma R T}\right)\frac{dV}{V} = -\frac{dA}{A}This shows the dependence on temperature. The relation assumes that...

It was only the psychrometry came; I read about vapour pressure is equal to the saturation pressure at 100% relative humidity. While before even in the textbooks both terms are used frequently as same. I fully understood what saturation pressure is; learned during phase change phenomenon of...

Homework Statement A certain humidifier operates by raising water to the boiling point and then evaporating it. Every minute 30 g of water at 20◦ C are added to replace the 30 g that are evaporated. The heat of fusion of water is 333 kJ/kg, the heat of vaporization is 2256 kJ/kg, and the...

Homework Statement The formation of ice from water is accompanied by: A. absorption of energy as heat B. temperature increase C. decrease in volume D. an evolution of heat E. temperature decrease For the first one I think it's correct but I don't know the explanation For second one it...

Homework Statement 55. Solid A, with mass M, is at its melting point TA. It is placed in thermal contact with solid B, with heat capacity CB and initially at temperature TB (TB > TA). The combination is thermally isolated. A has latent heat of fusion L and when it has melted has heat capacity...

Homework Statement The 4 processes involve one mole of either mono- or di-atomic gas with the same amount of heat (absorbed or discharged) •Which belong to the mono and which to the diatomic gas? Homework Equations i don't know which equations I should use and how start solving it.. I...

Suppose there is a test chamber containing liquid nitrogen. The container is insulated and only a small opening is there so that chamber is exposed to atmospheric condition. As the saturation temperature of liquid nitrogen is -196 degree Celsius at 1 atm pressure. chamber will remain at -196...

When we talk about entropy, we say it comes from our inability to completely describe the state of a system. Also, we say it is a property of the system (like entalphy). That's confusing me a lot. If entropy is a property, how can it come from our inability to describe the system? Or it's just a...

Gibbs phase rule says f = r-M+2 with f: thermodynamic degrees of freedom; r: number of components; M: number of phases I wonder whether the defintion of "phase" is restricted or almost arbitrary. For example, consider a system of H2O, O2 and H2 in a closed vessel. Let there be the contstraint...

Homework Statement As shown in figure. Homework Equations dq=msdt[/B]The Attempt at a Solution I am unable to understand the question,what is the significance of the moving piston if the ends of the conducting rod is maintained at constant temperature.It is enough if someone could explain...

I've just started with statistical mechanics and arrived at the part where they relate entropy to the number of microstates for a given system. The derivation starts of by adding an amount of heat ##\delta Q## to a system and observing the resulting change in internal energy : $$\delta U =...

Homework Statement A generalized TdS-equation for systems of several types of "work-parts" and varying number of particles in multiple components, is given by dU = TdS + \sum_{i}y_idX_i+\sum_{\alpha =1}^{c}\mu_\alpha dN_{\alpha} Thus, its natural to regard the internal energy U (an...

Homework Statement A gas obeys the equation of statez=1/(1-b(molar density)) What is the molar entropy change of expanding this gas from a volume of 1 dm3 to 2 dm3 at a temperature of 300 K, given b = 0.2 dm3? Calculate your answer to three significant figures and select one answer from the...

andrewkirk submitted a new PF Insights post Partial Differentiation Without Tears Continue reading the Original PF Insights Post.

Hello everybody, I have two questions: 1) Is it possible to define a temperature for single particle (or atom or molecule)? If so, how? 2) How to model with quantum Hamiltonian an exchange of energy between a single atom (or molecule) and a reservoir at given temperature ##T## ? Thank you...

Hi everyone! I am confusing myself with this topic and I would appreciate some insight into this. You see, one takes the area of a PV graph to obtain the work done on the system (for compression) or by the system (for expansion). However, I am learning that in the irreversible path, compression...

The reaction CO2 + 4 H2 <==> CH4 + 2 H2O (liq) at 25oC is downhill with a gibbs energy of -31 kcal/mol. It has a negative entropy of -98 cal/K. Thus an isolated system of the two starting gases should go to equilibrium on the basis of the Gibbs energy value, but the process would then...

Homework Statement When a gas is enclosed in an impermeable box and heated to a high temperature T, some of the neutral atoms lose an electron and become ions. If the number density of neutral atoms, ions and electrons is Na , N i and N e , respectively, these can be related to the average...

I learned about entropy is chemistry, can someone please explain how this term is used in physics? Thanks.

An ideal gas at initial state has temperature 300 K has been compressed under constant pressure of 30 Pa from volume 3 cubic meters to 1.8 cubic meters. In the process 75 J of heat was lost. A. Find the change in internal energy B. Find the final temperature I tried two methods in A and they...

Homework Statement Derive the equation ##U=-T(\frac{\partial A}{\partial T})_V## where ##U## is the internal energy, ##T## is the temperature, ##A## is the Helmholtz function. Reference: Heat and Thermodynamics, Zemansky, Dittman, Page 272, Problem 10.4 (a) Homework Equations ##dA=-PdV-SdT##...