Thermo Definition and 299 Threads

Homework Statement (This isn't for class, but still worthy of discussion!) If you heat a room with say a fireplace, why does the total energy not increase? Homework Equations PV=NkT The Attempt at a Solution This is a qualitative answer (mostly). The total energy of the...

Thermodynamics makes good predictions for macroscopic experiments, but the actual physics is going on in the microscopic particular level. The second law of thermo is often thrown around, usually by people who couldn't explain F=ma back to you. My question is the way the second law...

The value of H° for the reaction below is -1107 kJ: 2Ba(s) + O2(g) --> 2BaO(s) How many kJ of heat are released when 5.75 g of Ba(s) reacts completely with oxygen fo form BaO(s)? i worked out the moles of Ba which was 0.0412 then times by -1107 whcih is 46.4 however the answer is...

Homework Statement Water enters the constant 130-mm inside diameter tubes of a boiler at 7 Mpa and 65oC and leaves the tubes at 6 Mpa and 450[SUP]0C with a velocity of 80 m/s. Calculate the velocity at the inlet and the inlet volume flow rate Homework Equations The Attempt at a...

Thermo Help! Compressbility Homework Statement Ethane in a rigid vessel is to be heated from 50 psia and 100 F until its temperature is 600 F. What is the final pressure of the ethane as predicted by the compressibility chart? Homework Equations Pr=P/Pcr Tr=T/Tcr Pv=zRT The...

Homework Statement For acetone (1) methanol (2) system based on Wilson equation make the following calculations: (a) BUBL P: T=60oC, =0.3 (b) DEW P: T=60oC, =0.3 (c) PT-flash: T=60oC, P=1/2 (Pbubble+ Pdew), z1=0.3 (d) If an azeotrope exist at 60oC, find Paz and x1az=y1az ...

Homework Statement How do I write equations on a computer? I need some help with some Physics equations. I am about to take a course. I have very poor math skills, so I am hoping to improve my confidence, while learning some interesting equations. I have included Boyles Law as it is...

Homework Statement A nitrogen gas-liquid mixture is in a 20 cubic foot tank at a condition of 161 R with an initial quality of 0.1. Heating occurs at a rate of 10,000 Btu/h until the pressure reaches 100 psia. At this condition the BHE safety valve opens and maintains a constant pressure as...

Hi everyone, I was wondering if it might be possible to drive the spit on my barbeque using a thermo cyphon in a closed water system... The idea being to have a standard 22mm domestic copper pipe running through the bbq fire. Both ends of the pipe would be connected to a small water tank...

what is Vr... I know how to get Vr from my text but not sure what it is and what its used for...Im trying to find values for internal energy for an otto cycle question...im working on EES but only know how to get the values for Vr from the text

Homework Statement Classical Ideal Gas in 3 Dimensions In a classical ideal gas, we treat molecules as non-interacting point particles moving in the x,y, and z directions. These particles' velocities (in each respective direction) are statistically independent...

Hi...I would very much appreciate thermo help. I am using software that requires enthalpy data to be in units of J/m^3 (i.e., enthalpy per unit volume). The software also requires that enthalpy always increases with increasing temperature. My problem is that my enthalpy data in J/m3 do not...

Homework Statement The problem asks to find the energy conversion efficiency of a blower-nozzle combination that produces a velocity of 30m/s for air with a density of 1.1kg/mcubed. The nozzle has a diameter of .15m input power is 1 hp Homework Equations given the flow rate =...

Hello, I am trying to derive a formula for entropy. I have: dS= Cv/T dT + R/(V-b) dV and want to get: S= Cv*ln(T) + R*ln(V-b) + constant. Math rules seem to say i can't just integrate this up even though it looks obvious since i have two different d's on the right hand side. Maybe...

I have a test coming up tomorrow, looking for all the equations, I am in AP Physics course. TY

A partition separates the two compartments of a vessel. The vessel is submerged in a constant temperature bath at 200C. Compartment A contains 2.00 kg of water at 200C, 50.00 bar and compartment B contains 0.983 kg of water at 200C, 1.00 bar. The partition is removed and the water in both...

Homework Statement The light energy that falls on a square meter of ground over the course of a typical sunny day is about 20 MJ The average rate of electric energy consumption in one house is 1.0 kW one of the questions was: On average, how much energy does one house use during each 24...

Homework Statement A hypothetical substance has an isothermal compressibility k = a/v and an expansivity B = 2bT/v where a and b are constants and v is the molar volume. Show that the equation of state is v-bT2+aP = g where g is a constant. Homework Equations k= -v(dP/dv)T B =...

im given the equation: k d^{2}T/dx^{2} = 0 over 0 < x < L = 0.4 with T(0)=T and -k dT(L)/dx = h(T(L)-Tinf) i tried to solve it and i got T(x) = (-h(T(L)-Tinf)x)*(1/k) the book gives T(x) = ( (k+h(L-x))T+h*x*Tinf)*(1/ (k+h*L) ) i don't understand what went wrong... help!

Homework Statement A cylindrical container 80cm long is in two compartments separated by piston, clamped at 30cm from left end. The left compartment is filled with 1 mole of He at 5atm. Right compartment is filled with argon at 1atm. Both gases may be considered ideal. Cylinder is submerged...

Suppose the following system for a capacitor. Given: dE = TdS +\phi dq Where: \phi is the potential and = \frac{q}{C(T)} Find the heat absorbed in increasing charge from 0 to q. (Capacitance is a function of temp). So, I get dF = \phi dq and then F = \frac{q^2}{2C} Next, I tried...

I need some clarification! Thermo Cycle Homework Statement One kg of Refrigerant 22, initially at p1=.9MPa, u1=232.92 kJ/kG, is contained within a rigid closed tank. The tank is fitted with a paddle wheel that transfers energy to the refrigerant at a constant rate 0.1kW. Heat transfer from...

A 0.2-m-thick plane wall is constructed of concrete. At steady state the energy transfer rate by conduction through a 1-m^2 area of the wall is 0.15 kW. If the temperature distibution is linear through the wall, what is the temperature difference across the wall, in K? i don't even know where...

Homework Statement 10 moles of an ideal gas at 100 atm pressure are expanded isothermally against a constant pressure of 10 atm, to 10 at. calculate Q W deltaU and delta H (Take temp to be T)Homework Equations PV = nRT DeltaH = Q (for constant P) DeltaU = Q-W U = H+PV W = Integral(PdV)The...

I'm planning on taking a statistical thermodynamics grad course this Fall. Being an ME I am very familiar with classical thermo but what other topics should I be keen on? Any specific field of mathematics like abstract alg(only math I have not taken) I should be worried about? Also, I am...

Homework Statement A classical system of N distinguishable, non-interacting particles of mass m is placed in a 3D harmonic potential, U(r) = c \frac{x^2 + y^2 + z^2}{2 V^{2/3}} where V is a volume and c is a constant with units of energy. (a) Find the partition function and the...

Im building an outside vertical axis wind turbine. i need to build the (about 20) plastic fins that are going to be used to form the helix (which is the wind turbine) im trying to build the fins that are used on the helix wind turbine. a good video of it is on youtube: a crappy picture of...

can somebody help me in solving this problem..thanks.. A gaseous substance whose properties are unknown, except as specified below, undergoes an internally reversible process during which V = (-0.1p + 300)ft cube, when p is in psfa. (a) for this process, find -/ V dp and...

I am having trouble with this question...It is from "applied thermodynamics for engineering technologists" by Eastop (Q5.2 if anyone has it)... The Question: Two reversible heat engines operate in series between a source at 527°C and a sink at 17°C. If the engines have equal efficiencies and...

Homework Statement P=RT/(v-b) - a/(T(V+c)^2) Homework Equations u2-u1= Integral ( Cv dT) + Integral ( T * (dP/dT)v - P) dV The Attempt at a Solution I've differentiated P with respect to T to get R/(v-b)+a/(T^2(V+C)^2 and plugged the relevants back into the equation for...

Hello! This is a question purposed to me by my professor as we went over the mathematics behind the diffusion of heat flow through solids. Many parts of this question are left up to us to create. Here is what i am working with. ***** A m^3 box made of Brick .1m thick has air at 30C...

Homework Statement We are working on some problems for class and we are given statements which I accept as valid but don't know how to prove they are valid. I believe I have to utilize the maxwell relations but the terms seem unfamiliar to me.Homework Equations (1) Partial (d^2f / ds^2)_T = T /...

Why does du/dT = Cv, and same for Cp? Also, i don't understand how Cp/Cv = v, where v is the specific volume. It is derived from: Cv + R = Cp, how is PV=nRT used to get from Cv + R = Cp to Cp/Cv = v? I know n is replaced by m/M to leave Pv=RT where R would equal R(universal gas const)/M...

Can somebody please shed a little light on what this formula represents in the physical world? And how could I solve it to get \Delta H? \left[\frac{d\left(\frac{\Delta G}{T}\right)}{\delta T}\right]_p = \frac{\Delta H}{T^2}

Im studying for the Fundamentals of Engineering exam (coming up April 12!) and came across this Thermodynamics problem in my review book. So the work for an isothermal process is RTA*ln(VB/VA), where VA was previously determined to be 0.103m3. In the solution to the problem, the RTA term...

I have been messing up the partition function for thermo all semester, and now it's really starting to bite me with the carry-down error (i.e. mess up Z for (a) which in turn will mess up S in (b) and so on). I was looking at Reif Problem 9.1 and was wondering if someone could please explain...

[SOLVED] Thermo Energy. Iron + Ice Homework Statement A 50-g chunk of 80 degree C iron is dropped into a cavity in a very large block of ice at 0 degrees C. How many grams of ice will melt? (The specific heat capacity of iron is .11 cal/g*C)Homework Equations Q = cmdeltaT Quantity of heat =...

Problem 1: Homework Statement An ideal gas is heated reversibly at constant volume from T1 to T2. Calculate the entropy change of the system, the surroundings, and the universe. Homework Equations dS = dq/T (reversible change) and dq = CvdT (constant V) The Attempt at a Solution I know how...

Can you help me to extend the BCS theory developed in Thermo Dynamics (TFD) formalism to high-temperature superconductivity?

Homework Statement A chemical reaction is a gas mixture at 500 degrees C decreases the number of moles of gas, which is assumed to behave ideally, by 34.7%. If the internal energy change is 23.8 kJ, what is the value of dH. Homework Equations Not sure if they are complete relevant...

Homework Statement A rigid vessel of total volume 0.5m3 contains 1kg of air at 15°C initially constrained in a volume of 0.06m3 by a diaphragm. The remaining volume is completely evacuated (pressure = 0). If the diaphragm is burst, allowing free adiabatic expansion of the air, determine...

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Could you please give me a walk through on how to solve for volume of a substance using the Peng-Robinson Equation of State, given: 1. initial and final pressure 2. initial and final temperature (it is an isotherm) 3. it is frictionless (all work is reversible) P=...

Thermo --> Heat Pump, confirmation. Homework Statement A cooling unit for a fridge has a 100 W power input. Environment temperature is 298 K. The heat which enters the fridge due to defective isolation is 350 W. What is the minimal temperature the fridge can reach? Homework Equations...

I have some equipment that uses an older refrigerant that I am having a hard time finding any uselful data on. It is r-144a, and if anyone has any idea as to where I could find a thermo properties table on this stuff, let me know. I've been looking everywhere, hundreds of websites, countless...

I have this multiple choice question: Two thin strips of iron and zinc are riveted together to form a bimetallic strip that bends when heated. The iron is on the inside of the bend because: (A) it has a higher coefficient of linear expansion (B) it has a lower coefficient of linear...

Basically, I have a project involving thermally tunable photonic crystals and part of the essay in the run up to the experiment work I want to write a bit on the thermo optical effect, but I have searched in vain for a resource for this. Can anyone suggest a textbook or something online? Thanks.

Homework Statement Saturated liquid water contained in a closed, rigid tank is cooled to a final state where the temperature is 50 degrees C and the masses of saturated vapor and liquid present are 0.03 and 1999.97 kg, respectively. Determine the heat transfer for the process, in kJ...

A question about metal thermo flasks, or metal vacuum flasks if you prefer. I understand the principle of thermo/vacuum flasks. Just to proofed that I read up before posting this question :-) http://en.wikipedia.org/wiki/Vacuum_flask But today I had a look at on of those new-isch thermo...

Homework Statement Imagine some helium in a cylinder with an initial volume of 1 liter and an initial pressure of 1 atm. Somehow the helium is made to expand to a final volume of 3 liters, in such a way that its pressure rises in direct proportion to its volume. (a) Sketch a graph of...