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

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Molecular formula of a compund [closed]

I have no idea on how to get information out of this one. A compound contains only hydrogen and nitrogen. Nitrogen makes up for 87.4% of the mass. A sample of this have a density of 0.977 g/L at ...
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1answer
339 views

Is temperature-induced change in the volume of balloons dependent on gas?

Which balloon will have higher relative change in volume, helium balloon immersed in liquid nitrogen or air balloon immersed in liquid nitrogen? Since volume is directly proportional to temperature ...
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1answer
393 views

Work done on gas by piston [closed]

In this problem there is a cylinder that is closed at both ends and has thermally insulated walls. It is divided into 2 parts by a movable, frictionless, thermally insulated piston. There is a ...
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4answers
1k views

Why does this perpetuum mobile not work?(Gases and Densities) [duplicate]

I recently came up with the following concept. It is very simple, and may have been thought of before. A picture says more than a thousand words, so here is it explained in a picture: Note that ...
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2answers
433 views

Why doesnt this violate 2nd law of thermodynamics?

Consider an ideal gas in a cylindrical container in a gravitational field, with a piston on top pushing down by gravity. The piston has some locking mechanism that locks it in place if it is displaced ...
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1answer
348 views

Volume quotient in Carnot-cycle

Problem: One kilomole of an ideal, monatomic gas undergoes a reversible Carnot-processes between temperatures 300 °C and 20 °C. The work done during one cycle is 1500 kJ. a) Find the ...
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622 views

Problem involving 1st law of thermo and ideal gas law

Problem: $1.0 \text{ kg}$ of air at pressure $10^6 \text{ Pa}$ and temperature $398 \text{ K}$ expands to a five times greater volume. The expansion occurs such that in every instance the added ...
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1answer
683 views

Expression for kinetic energy of gas per molecule

The average kinetic energy (KE) per molecule of a gas is $\frac{3}{2}kT$. While finding this we do $$ \text{ Average KE} =\frac{1}{2} M \frac{1}{N}\sum v^2=\frac{3}{2}kT$$ But why do we not add ...
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3answers
99 views

Behavior of gasses, ideal and otherwise

I'm trying to help a child research a science project on refrigeration. Refreshing my incredibly rusty thermodynamics skills.... The ideal gas law: $PV=nRT$. Let's take air at STP: $P = 101\,kPa$ $V ...
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1answer
304 views

Why is there a sign error in my derivation? Adiabatic expansion of ideal gas: $TV^{1-\gamma}$ is constant

This is the last part of a derivation of the equation for an ideal gas undergoing reversible adiabatic expansion. I'm trying to prove that $T V^{\gamma-1}$ is constant, but my result is that $T ...
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0answers
166 views

Sound velocity in ideal Bose gas

Speed of sound is related to the derivative of pressure with respect to density: $v_s=\sqrt{(\frac{\partial P}{\partial \rho})_S}$ where S tells us the derivative must be taken while keeping entropy ...
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1answer
478 views

Rate of effusion in kinetic molecular theory?

According to the kinetic molecular theory obeying Maxwell-Boltzmann distribution of speeds, the rate of effusion through a pinhole of area $A$ is $$R=\frac{PA}{\sqrt{2\pi M R T}}$$ where $M$ is the ...
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2answers
190 views

Ideal Gas Constant

Wikipedia states that the ideal gas constant relates the energy scale to the temperature scale. It serves as the constant of proportionality. This is obvious from the units. If temperature is a ...
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1answer
2k views

Estimate temperature and pressure of steam in a pot of boiling water

Suppose we have a pot of known dimensions filled to level L with boiling water on a stove, covered by a lid with a vent of known dimensions. Given the steady-state temperature of the stove (bottom of ...
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2answers
223 views

Would the temperature of a gas change when accelerated in a train?

I was thinking about a situation where some gas is enclosed inside a container and kept in a train at rest. The train accelerates, gains a maximum speed and then suddenly stops. Would the temperature ...
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1answer
945 views

Simple explanation of relation between speed of sound and r.m.s. speed?

In an ideal gas, the speed of sound $v_s$ is related to the r.m.s. molecular speed $v_m$ by $$\frac{v_s}{v_m}=\sqrt{\frac{\gamma}{3}} \qquad ,$$ where $\gamma=C_p/C_v=7/5$ for a diatomic gas. I ...
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2answers
749 views

Adiabatic filling of a container

Suppose a thermally insulated container is filled with atmospheric air until the pressure reaches 5000 psi. This could represent the filling of a diving cylinder, before thermal dissipation becomes ...
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1answer
2k views

Heavy vs Light Particle Ideal Gases

Assume there are two ideal gases. The first is made of a light particle, and the second is made of a heavy particle. The two are of the same amount, in the same volume container, and at the same ...
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1answer
157 views

How do I find the amount of atoms in a pure gas in a confined area?

Say I have Argon gas in an area such as a cube with pressure around pressure between 10-5 and 10-3 Torr (pressure) at 25 degrees at 320 Kelvins . How do I find the amount of atoms in that cube? Any ...
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2answers
793 views

How does a gas of particles with uniform speed reach the Maxwell-Boltzmann distribution?

Take an empty container and fill it with $N$ gas particles (ideally a monoatomic gas), each having the same kinetic energy $E$, then isolate the container. Since initially the speeds don't follow the ...
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1answer
880 views

Density of Air in a balloon

A balloon with volume 2800 m³ is heated up to 60 °C. If the outer temperature is 12 °C and the air has a pressure of 960 hPa, what is the density of the air inside the balloon and on the ...
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1answer
50 views

What portion of impulse is received by the cylinder?

Condition: A cylinder with a piston are situated along Y axis. Piston receives an impulse (P1) along Y axis and transmits it to the cylinder through a gas medium with which cylinder is filled. The ...
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2answers
170 views

Combined gas law in an open atmosphere

The question was asked about pressure vs. Volume increasing in an ideal gas as temperature is increased. My question then is this. What is the formula to determine how much volume and pressure will ...
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2answers
6k views

In an ideal gas, if temperature increases, will pressure or volume increase?

This question came up when I was talking about the atmosphere. Someone had mistakenly claimed that as temperature increases, the density of the atmosphere should increase as well. I reasoned from the ...
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479 views

Understanding Charles's Law

Charles's law states that, The volume of a given mass of an ideal gas is directly proportional to its temperature on the absolute temperature scale (in Kelvin) if pressure and the amount of gas ...
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741 views

Why is steam used to spin turbines?

The ideal gas law tells us that the relationship between Pressure (P), Volume (V), Temprature (T), and quantity/amount (n) is $$ PV = nRT $$ where R is the gas constant. Say your an engineer who ...
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640 views

Costant volume gas thermometer [closed]

I have two constant volume gas thermometers, one with an ideal gas $pv=RT$ and the other following the Van der Waals equation $(p+\frac{a}{v^2})(v-b)=RT$. They are calibrated using the freezing point ...
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278 views

ideal gas law modelization in a vacuum chamber

I am trying to model a pressure sensor in COMSOL. The basic work is that there is current flowing inside it, if the pressure of the gas around it drops down, the temperature goes down as well (ideal ...
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1answer
60 views

What is the $\delta$ in fluctuation model [closed]

I found this formula : $G-G_0=\frac{-nkT}2\delta^2$ on this Site and I'd like to ask what does the $\delta$ stand for?
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1answer
420 views

Average force and pressure in a 3D box due to quantum non-interacting particles

A gas of non-interacting quantum particles occupies a box with lengths $L_1, L_2, L_3$. Calculate its energy and thus the average force and pressure exerted by the gas on the walls of the box. I have ...
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1answer
72 views

Compression of a liquid with a gas dissolved in it?

If I remember correctly you cannot compress a liquid, but I know you can compress a gas. (usually to the point it becomes a liquid then no further) What happens if I were to compress soda water? A ...
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1answer
93 views

error propagation and collision in ideal gas

When dealing with gas, a statistical approach is needed because For N particles, you have to solve 6N equations which cant be done analytically. To know our time step for numerical solving, you can ...
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3k views

Air pressure in balloon

I have to calculate the air pressure inside of an hot air balloon. After some searching I found out that I can use the ideal gas law: PV = nRT (from Wikipedia) So to get the pressure in the balloon I ...
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105 views

Is it possible to obtain higher order corrections to the ideal gas law when one allows realistic phenomena to make their way into the equations?

I had an interesting thought today that caused me to ask whether it'd be possible to make corrections to the ideal gas law via introducing terms derived from more realistic phenomena to make their ...
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0answers
479 views

How can I interpret negative values of potential evapotranspiration?

If I extract Potential Evaporation (PET, W/m$^2$) from the National Centers for Environmental Prediction (NCEP), climate reanalysis data (downloadable as netCDF files here), there are some negative ...
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1answer
128 views

How fair is it to say that all chemistry arises from failures of the ideal gas law?

I was reading here about how the ideal gas law assumes point masses and non-interaction. Is it fair to say that all chemistry arises from failures of that? Of course, such a sweeping generalization ...
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1answer
291 views

Volume of gas at which relative fluctuation of gas density occurs

I have the following question: In what volume of gas occurs 10 % relative fluctuation of gas density under pressure of $10^5\text{ Pa}$ and temperature of $293.15\text{ K}$? I don't understand ...
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3answers
368 views

Conversion of ideal gas to real gas via $Z$ compression factor

The ideal gas equation $PV=nRT$ can be converted into real gas equation by compression factor $Z$ i.e $PV=Z~ nRT)$. My question is what is $Z$ and how does it arise? Is $PV/nRT$ a compression ratio of ...
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2answers
946 views

What are the units of these virial coefficients?

I'm reading some papers for calculating the vapor pressure of alkali metals as a function of temperature, and I've come across some familiar-looking virial expansions, but when I tried to work out the ...
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2answers
490 views

Calculating air density lapse with altitude (specifically, pressures)

This might be a bit more of an engineering question, but I'm calculating air density drop-off with altitude, and I'm having some problems calculating the pressure (I'll run through my method). This ...
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3answers
834 views

Temperature change inside pressure chamber

Let's say there is a pressure chamber with some sort of sample / specimen (e.g. protein crystal) in it. Now I apply a certain amount of gas pressure, e.g. 10 or 20 atm. Let's say I use xenon as a gas. ...
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1answer
77 views

In $PdV$, what is the value of $P$? $P_1$ or $P_2$?

Say I have an ideal gas that has a known $P_1$, $P_2$, $T_1$, and $T_2$ undergoing a reversible adiabatic process. I want to find the work done so I must use $PV = RT$ to get the change in $V$, so ...
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2answers
718 views

Canonical partition of a boson gas

I have a 1D gas made of $N$ particles placed in a harmonic potential well, so the Hamiltonian is: $$ \mathcal H = \sum_{j=1}^N \left ( \frac{p_j^2}{2m} + \frac{1}{2}m\omega^2 x_j^2 \right )$$ The ...
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1answer
8k views

How to calculate the specific heat capacity of gases

Could someone explain why the Specific Heat Capacity (SHC) of dry air is 1.005kJ/kg.K whereas the accepted SHC for ventilation air is quoted 1.300kJ/kg.K? Assuming the air for the ventilation calc’s ...
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2answers
5k views

Root Mean Square Speed of Gas

The RMS speed of particles in a gas is $v_{rms} = \sqrt{\frac{3RT}{M}}$ where $M$ = molar mass; according to this Wiki entry: http://en.wikipedia.org/wiki/Root-mean-square_speed The gas laws ...
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1answer
330 views

Ideal gas temperature and pressure gradients?

Consider an ideal gas in a $d\times d\times L$ box with the $L$ dimension in the $x$-direction. Suppose that the opposite $d\times d$ sides of the box are held at temperatures $T_1$ and $T_2$ with ...
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463 views

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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2answers
988 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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77 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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2answers
5k views

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: ...