A gas that behaves as randomly moving, non-interacting molecules. This allows a simplified equation of state.

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Ideal gas concentration under temperature gradient

I'm trying to calculate the concentration of an ideal gas in an adiabatic container as a function of position where the top and bottom plates of the container are fixed at temperatures $T_1$ and ...
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774 views

With ideal gases, varying quantity of moles, and having a constant volume how do temperature and pressure behave?

I'm trying to build a simulation of gases so I ended-up trying to use law of ideal gases ($PV = nRT$). In my scenario: volume is constant ($V=1\rm{m}^3$); a known quantity of moles are being added ...
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68 views

Experimental data for gas flow through pipelines

Maybe some of you could point a good source of experimental data of gas flow through pipelines? What I need is a very simple flow of some gases through some diameter simple linear pipeline. A graph of ...
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Adiabatic process of an ideal gas derivation

I am working through the derivation of an adiabatic process of an ideal gas $pV^{\gamma}$ and I can't see how to go from one step to the next. Here is my derivation so far which I understand: ...
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645 views

Understanding mathematically the free expansion process of an ideal gas

I'm trying to understand mathematically that for the free expansion of an ideal gas the internal energy $E$ just depends on temperature $T$ and not volume $V$. In the free expansion process the ...
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1answer
77 views

Working out the mean velocity of particles in a gas

I'm trying to answer the following question: Air consists of molecules Oxygen (Molecular mass = 32$amu$) and Nitrogen (Molecular mass = 28$amu$). Calculate the two mean translational kinetic ...
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92 views

Using thermodynamics and Kinematics together to solve a parachuter problem?

I need to find a parachutist's displacement after a given height (nearly 37000m) and at a given latitude. I have his mass, area, parachute area, drop height, parachute deployment height, data about ...
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1answer
94 views

Problem evaluating moles in a an isochor transformation

I have a problem with an isochor transformation. Me and my group of study made an experiment that want to check Gay-Lussac’s law. We registered the equilibrium states and fitted the $P = nRT / V$, ...
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1answer
110 views

Thermodynamic process when nebula is heated

The basic thermodynamics problem is stated as follows. The nebula contains a very tenuous gas of a given number density (atoms per volume) that is being heated to a given temperature. What is the ...
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How to deduce E=(3/2)kT?

It says in my course notes that a particle has so-called "kinetic energy" $E=\frac{3}{2}kT=\frac{1}{2}mv^²$ Where does this formula come from? What is k?
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1answer
363 views

Velocity of real gas molecules?

It is known that the velocity of ideal gas molecules can be computed using Maxwell-Boltzmann law of distribution of molecular velocities, with average velocity given as: ...
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468 views

Will ideal gas law apply to plasma?

I have read that plasma is a state of matter that resembles gas but it consists of ions and electrons coexisting. So my question is : If plasma is just ionized gas, will ideal gas law apply for it ?
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Is it possible to find the number of gas atoms/molecules in a box when the number is small?

Given very low number of particles in a system (e.g. in the 100s), is there a way to accurately measure the number of particles in the system? Assume temperature, pressure and volume is constant and ...
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2answers
6k views

Calculating work done on an ideal gas

I am trying to calculate the work done on an ideal gas in a piston set up where temperature is kept constant. I am given the volume, pressure and temperature. I know from Boyle's law that volume is ...
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1answer
827 views

Adiabatic expansion [closed]

I'll start off by saying this is homework, but I ask because I don't understand how the math should work (I don't just want an answer, I'd like an explanation if possible). I understand if this is ...
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1answer
63 views

Performing work on a box of gas by lifting it, and first law of thermodynamics

What happens if we lift a box of ideal gas? Work is done to the box but no heat is getting into it. So does it's internal energy increase by the amount of work done? Or is it that lifting is not ...
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1answer
265 views

Ideal gas and diatomic gas with same temperature

If a box of ideal gas and another box of diatomic gas are in thermal equilibrium, does it mean that the average translational energy of ideal gas particle (A) is the same as that of diatomic gas ...
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1answer
3k views

Work Done by an Adiabatic Expansion

I am given the information that a parcel of air expands adiabatically (no exchange of heat between parcel and its surroundings) to five times its original volume, and its initial temperature is 20° C. ...
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1answer
3k views

Work Done in an Isobaric Process

I am given the information that an air parcel undergoes isobaric heating from 0° C to 20° C, and that's all I'm given. I have to determine the work done by the parcel on its surroundings. I know that ...
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1answer
235 views

Which heated, partially filled bottle will explode first?

This is in reference to a pasteurization discussion on a homebrewing forum. I have four closed bottles which will explode if containing too much pressure. Two of them are 50% full (A and B), and two ...
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3k views

Ideal gas law, pressure increase and temperature

If I had a container, full with air, and I suddenly decreased the volume of the container, forcing the air into a smaller volume, will it be considered as compression, will it result in an increase in ...
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1answer
2k views

Work on ideal gas by piston

Imagine a thermally insulated cylinder containing a ideal gas closed at one end by a piston. If the piston is moved rapidly, so the gas expands from $V_i$ to $V_f$. The expanding gas will do work ...
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1answer
290 views

speed of sound and the potential energy of an ideal gas; Goldstein derivation

I am looking the derivation of the speed of sound in Goldstein's Classical Mechanics (sec. 11-3, pp. 356-358, 1st ed). In order to write down the Lagrangian, he needs the kinetic and potential ...
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1answer
516 views

Difference in vertical stratification of partial pressure due to gravity

Say you have a mixture of two ideal gases in the presence of gravity. There is a vertical pressure gradient on the mixture due to the force balance. This condition is required to prevent the entire ...
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2answers
462 views

Is it Possible to have Adiabatic Processes other than $PV^\gamma$ for the ideal Gas?

Is it possible to represent an adiabatic process for an ideal gas by a formula other than $PV^\gamma=Const$?: Relevant Considerations: We always need to connect a pair of arbitrary points/states ...
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1answer
2k views

Calculate mass of air in a tyre from pressure

How can one calculate the mass of air inside a tyre, given a particular tyre size; a pressure, in $kPa = \frac{1000kg}{m\cdot s^2}$; and assuming room temperature, and normal air composition? I can't ...
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141 views

May molecules of ideal gases have an inner structure?

The following question is probably very elementary: whether molecules of ideal gases may have optic properties? As far as I understand, when one discusses optic properties, one assumes that molecules ...
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Why are volume and pressure inversely proportional to each other?

It makes sense, that if you have a balloon and press it down with your hands, the volume will decrease and the pressure will increase. This confirms Boyle's Law, $ pV=k=nRT $. But what if the ...
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1answer
496 views

What is the pressure drop in a venturi with a compressible fluid?

I would like to know if there is an equation to predict the pressure drop in a venturi device using a compressible fluid as the working medium. In particular, I'd like to use this equation to predict ...
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206 views

Centrifugal Compressor Flow Rate

For a centrifugal compressor, as found in most turbochargers on internal combustion engines, is there a noticeable change in flow rate versus a naturally aspirated flow rate? In other words, does the ...
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1answer
243 views

Black body balloon in vacuum [closed]

The problem statement, all variables and given/known data There is a perfectly spherical balloon with surface painted black. It is placed in a perfect vacuum. It is gently inflated with an ideal ...
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3answers
783 views

What does it take to derive the ideal gas law in themodynamics?

How can the ideal gas law be derived from the following assumptions/observations/postulates, and these only ? I'm able to measure pressure $P$ and volume $V$ for gases. I notices that if ...
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1answer
876 views

Collision frequency at surfaces

Collision frequency for particles in gases is well known, and collision theory is used to derive chemical reaction rates in gases, (and particles in liquid solutions as well). Using the mean velocity ...
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221 views

Expansion of Helmholtz energy

To get an expansion of Helmholtz energy of a) an ideal gas b) a Van der waals gas we must integrate $\left ( \frac{\delta A }{\delta V} \right )_{T}=-P$ I saw the solution is : Can you ...
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1answer
231 views

Energy formula for separating $O_2$ from mixture of $O_2$, $NH_3$ and $H_2O$

I have a physics problem I'd like to make sure I get correct. The practical aspect of this problem is that the photosynthetic efficiency of algae is inhibited with dissolved O2 in the growth medium, ...
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3answers
2k views

When a gas expands against an external pressure of 0, must the stopper on the cylinder be massless?

Basically, I need to conceptually understand why the work a gas does is the integral $\int p_\mathrm{external}dv$ and is 0 when pressure external is 0. I understand why $\mathrm{d}w = - ...
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271 views

Simple question about a gas in a box with a moving wall

David Albert is a philosopher of Science at Columbia. His book "Time and Chance" includes this example (p 36). A gas is confined on one side of a box with a removable wall. "Draw the wall out, ...
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314 views

What would be pressure of 1 kg of photon gas at room temperature put in a volume of 1 liter?

Suppose a number of photons with spectrum corresponding to black body spectrum at 293 K with total energy corresponding to 1 kg put in a box with ideal mirror walls with volume of 1/1000 of a cubic ...
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Differentiating the ideal gas law

In reading Fermi's Thermodynamics, to show that $C_p = C_v + R$, the author differentiates the ideal gas law for a mole of gas ($PV = RT$) to obtain: $PdV + VdP = RdT$. Now, the only way I am able to ...
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2answers
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Why does a gas get hot when suddenly compressed? What is happening at the molecular level?

My guess is that the molecules of gas all have the same speed as before, but now there are much more collisions per unit area onto the thermometer, thus making the thermometer read a higher ...
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What type of substances allows the use of the Ideal Gas Law?

I know that I can use the ideal gas law with pure gases or pure liquids. But can I also use the ideal gas law at saturated gases and saturated liquids as long as they aren't two phase substances?
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How slow is a reversible adiabatic expansion of an ideal gas?

A truly reversible thermodynamic process needs to be infinitesimally displaced from equilibrium at all times and therefore takes infinite time to complete. However, if I execute the process slowly, I ...