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

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Nitrogen generator maximum flow check

We have a N2 PSA unit with following specs Now I have done some calculations as shown in the image. Assuming 0.8% of the air is (N2+inerts) rest being O2 can someone tell me that how 160CFM air ...
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64 views

Kinetic Theory of Gases: Why do gas molecules have translational motion?

The title pretty much asks the question. I was reminded of the Kinetic Theory of Gases recently and I am puzzled as to why gas molecules would have any translational motion. Is it because collisions ...
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57 views

What does a sample of the Sun look like? Does it look like fire or gas?

Suppose that in the future a highly resistant spacecraft went to the Sun and collected three samples of the Sun: one from its surface, one from its core, and one midway. The three samples were put ...
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133 views

Balloon gas temperature experiment in water

In this problem set I have a passage that describes an experiment that looks at the changing temperature as an air filled balloon rises to the surface from the bottom of a water filled tank. The graph ...
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3answers
296 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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74 views

Does QM needs refinement?

Suppose atoms of an ideal gas are represented by non overlapping wave function so that the system can be described classically. As time passes the packets spread. Therefore over a period of time we ...
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7k views

What is the $C_p/C_v$ ratio?

Recently in our chemistry class we read that the $C_p/C_v$ ratio of the inert gases is 1.66 thus they show inert nature. I asked my teacher what was $C_p/C_v$ ratio but he didn't answer me. So I want ...
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24 views

Cylinders of two identical gas composites [closed]

I think the answer is B because gas pressure only changes when the temperature is changed and the volume does not change since this element did not change. The physics concept that is in regard is ...
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1answer
32 views

Coefficient of volume expansion for gases

I often read that at 0 degree (Centigrade), gases expand by 1/273 of its volume at 0 degree for one degree rise in temp. So does this coefficient of expansion ( i.e. 1/273) change with temperature?
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11 views

What are the Correlations for the Super-compressability Z factor?

I am studying the course TPG4145 Reservoir fluids in NTNU and specifically the supercompressability factor $Z=\frac{V_{\text{real volume of the system}}}{V_{\text{ideal volume of the system}}}$ for ...
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1answer
33 views

Thermodynamics - ideal gas [closed]

Question: 1 mol of a monoatomic gas at 298 Kelvin acquires a volume of 3 litres. It is expanded adiabatically and reversibly to a pressure of of 1 atm. It is then compressed isothermally and ...
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26 views

Mean square velocity of an ideal Bose gas

I'm trying to find the mean square velocity of a particle in an ideal Bose gas. The equation is given by: $\langle v^2 \rangle = \dfrac{1}{N}\displaystyle\sum_{\vec{k}}(\hbar ...
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Dielectric constant of gases - constant?

A number of questions related to the topic: Is the dielectric constant actually constant as a function of temperature and frequency (when used in a capacitor)? Is it constant as a function of field ...
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1answer
76 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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2answers
103 views

$E=kT$ or $\frac32kT$?

Basically, which is the correct formula for thermal energy, and is this the same as kinetic energy? My notes are pretty conflicting on this topic, and I'm getting pretty confused.
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Adiabatic Relation in Plasma Invariant and Thermodynamics

In the problem above, I know how to do the 1D part. Basically, you just plug $V_{l\,l} = \frac{J}{L}$ into $\langle \frac{1}{2} m v^2\rangle = \frac{1}{2} k T$. After you get $T$ in terms of $L$, ...
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1answer
118 views

Ideal gas in ensemble

I want to calculate the phase space density for a single ideal gas particle in a microcanonical ensemble. I know that the partition function is given by the well-known expression that you find for ...
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46 views

How does EM heating cause motion?

Similar to how does heating cause motion, I'm trying to understand how a photon imparts motion to an atom, i.e. adds heat to a gas. I'm going to hazard a guess, and suggest this occurs something ...
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36 views

Is collision in ideal gas because of physical collision or due to repulsion force

Is collision in ideal gas because of physical collision or due to repulsion force when they approach close by?
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28 views

Nonlinear constitutive state equation

Between the Tait equation, and the B/A type of equation, which one is better suited to approximate the isentropic equation of state? Why B/A type is mostly used in nonlinear acoustics?
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A model for surface adsorption

I have been trying to model the adsorption of an inert gas on the surface of a clean solid. So far my underlying goal is to express the Gibbs energy as a function of the number $N$ of adsorbed ...
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1answer
36 views

Why do tires need to be inflated when the temperature changes?

Why do you need to add air to your tires when the temperature drops? The temperature inside and outside of the tire is the same (let's assume that you aren't currently driving, and your car has been ...
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53 views

Thermodynamics: Caclulate final temperature with hot metal in gas [closed]

I've been working on this problem for a couple of hours now, and I think that I simply don't understand the basic principles that tie into the problem: (note that I attempted this problem and it was ...
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1answer
614 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
219 views

Work Done in a Thermodynamic System (Cylinder with Piston) [closed]

Heated Piston A cylinder of cross-sectional area 0.0314m^2, filled with argon (a monatomic ideal gas), is sealed with a piston of mass M=25kg that is free to move up and down. The piston is ...
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194 views

How do gas molecules constantly bounce without losing energy?

From a related question (How does pressurized gas constantly push?), i asked myself this: How do gas molecules constantly bounce off each other without losing energy? If you drop a ball, it bounces a ...
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358 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
117 views

How long does it take to equalize pressure of two gas containers?

I'm looking for an equation that will tell me how long it takes for two gases at two different pressures to equalize their pressures. As a more concrete question, Container 1 has gas at pressure P1. ...
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1answer
39 views

Ideal gas law in open volumes

I often find in text books that the ideal gas law given by $p\cdot V=m\cdot R\cdot T$ is applicable in a closed system, still, some use it for open systems (like freezing the system at a given ...
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41 views

What happens to the gas in the container in this picture when the container is tilted

So the test question asked what would happen to the gas if this container were tilted on its side. The piston shown here is 10 kg and moves frictionlessly. I said that the pressure inside the ...
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2answers
95 views

Why Earth's atmosphere behaves like an ideal gas?

In every book I found this sentence like an assumption, without explananions, somebody can help me understand it better?
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1answer
950 views

What happens to the temperature when an ideal gas is compressed?

I am rather confused about this. I know from Charles' law that under constant pressure, the volume of a gas is directly proportional to its absolute temperature i.e. $$\frac{V_1}{T_1} = ...
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45 views

Simple gas in cylinder modeling

I want to do a simple (physically plausible but not physically accurate) simulation of a gas in a cylinder as it works on or is worked on by a piston. Wikipedia gives a good example of an adiabatic ...
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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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156 views

How to calculate the buoyant force on a balloon at different altitudes [duplicate]

For a project into balloon simulation I'd like to know how the force on a balloon changes with altitude: I know that the Buoyant force on a balloon is: $F = (\rho_{air} - \rho_{helium})gV$ Using ...
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Recombination time for ionized atoms in a low pressure gas?

I am looking into some new physics and had the following question come up: You have a neutral gas of let's say, CO atoms at 1 nanoTorr. An electron(s) comes passing through the gas ionizing only 1% ...
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Enthalpy Change in Reversible, Isothermal Expansion of Ideal Gas

For the reversible isothermal expansion of an ideal gas: $${∆H}={∆U}=0 \tag1$$ This is obvious for the case of internal energy because $${∆U} = \frac {3}{2} n R {∆T} = 0 \tag2$$ and $${∆U} = -C_P n ...
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Partial Pressure - Which solution is right?

Question: Carbon dioxide (1.100 g) was introduced into a 1.00 L flask which contained some pure oxygen gas. The flask was warmed to 373 K and the pressure was then found to be 608 mmHg. If CO2 and O2 ...
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51 views

Average ocupancy in an ideal gas at high-temperature

In David Chandler's 'intro to statistical mechanics' he states that for an ideal gas at high-temperature $$ \langle n_j\rangle=\langle N\rangle\frac{e^{-\beta \epsilon_j}}{\sum e^{-\beta \epsilon_j}} ...
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98 views

Simple expression for transitional pressure force

Consider a simple, circular orifice with an upstream, high gas pressure and downstream, normal atmospheric pressure. Consider also a flat circular plate that can be positioned anywhere along the ...
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Is enthalpy also valid for liquids and solids?

The definition of enthalpy is $$H=E+PV,$$ is it only valid for (ideal) gas? As this naturally comes from the first law of thermodynamics, $$dE=dQ+PdV$$ for a enclosed system of gas. Can we talk ...
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logarithm of ideal gas law

This question is about taking the logarithm of the ideal gas law. In a fluids text book the author writes: First recall a couple of ideal gas relationships involving potential temperature, ...
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136 views

Can we apply $pV^\gamma$=const only for quasistatic adiabatic process?

But If this is so, I have often seen people applying this formula for quick processes where no heat exchange is possible. Here is an example from where I am quoting the following: we will assume ...
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114 views

Finding Interatomic Spacing

Here is the problem I am working on For what temperatures are the atoms in an ideal gas at pressure P quantum mechanical ? Hint: use the ideal gas law P V = N kT to deduce the interatomic spacing ...
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156 views

Help with ideal gas law manipulation

Equation 1 represents an improvement over the intial assumption of constant mass velocity (i.e., $\rho v=\rho_o v_o$). We can now improve Eqn. (2) to get to Eqn. (3). My question is: what are the ...
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1answer
53 views

Examples of nearly perfect fluids and gases

When learning for physics (hydrodynamics and gases) I wanted to know what would be examples of nearly perfect fluids (no surface effects and no friction) and perfect gases (only elastic collisions and ...
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127 views

Mass of air inside air balloon

I have an exercise here with a solution. The basic outline of the problem is: Calculate the mass of air inside a hot air balloon, given the mass of the air balloon at rest is $m_b = ...
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1answer
47 views

Thermal expansion coefficient times temperature: under which condition is it unity?

In Landau's Fluid Mechanics p. 8 (2nd edition) he writes for the thermal expansion coefficient $\beta = (1/V) (\partial V/\partial T)_P$: For a column of gas in equilibrium which can be taken as a ...
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Not Quasi-static, yet reversible process? Is this a valid example?

Imagine a gas (at room temp. and pressure) enclosed in a thermally insulating spherical container. At some instant, the container instantly expands symmetrically (radially outward) to, say, twenty ...