Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide). A gas mixture, such as air, contains a variety of pure gases. What distinguishes a gas from liquids and solids is the vast separation of the individual gas particles. This separation usually makes a colorless gas invisible to the human observer. The interaction of gas particles in the presence of electric and gravitational fields are considered negligible, as indicated by the constant velocity vectors in the image.
The gaseous state of matter occurs between the liquid and plasma states, the latter of which provides the upper temperature boundary for gases. Bounding the lower end of the temperature scale lie degenerative quantum gases which are gaining increasing attention.
High-density atomic gases super-cooled to very low temperatures are classified by their statistical behavior as either Bose gases or Fermi gases. For a comprehensive listing of these exotic states of matter see list of states of matter.
Hi all,
A happy 2018 for all PF members.
I have a question. I am trying to understand some basic principle of thermodynamics. My book tells me tge following:
"Heating of a gas at a constant pressure uses more heat as when heating the same gas a constant volume"
How do i interpret this? I...
We consider a monoatomic gas in a closed box.
A textbook says :
Since the assumption is that the particles move in random directions, the average value of velocity squared along each direction must be same.
Why the assumption is that the particles move in random directions implies that the...
In the first volume of his lectures' books, Feynman tries to mathematically describe that in a particular gas ( particular because in this case is the sum of 2 monoatomic gasses with different masses) as a result of the collisions beetween atoms it will be equally likely to find any pair moving...
Homework Statement Homework EquationsThe Attempt at a Solution
## \frac 1 2 m<v_x^2> =\frac 1 2 k_BT ,
\\ \sqrt{ <v_x^2>} = 556~ m/s ## So, I guess that the standard deviation should be less than rms speed.
So, the option is (a)
## \left< ax + b \right> = a\left<x\right> + b...
Homework Statement
Re-arranging the equations of potential (internal) energy in a monoatomic gas, i get this differential equation:
\gamma (dV/V ) + (dP/P) = 0.
where V is volume and P is pressure.
I have to integrate it.
Homework EquationsThe Attempt at a Solution
I tried, but i wasnt able...
Homework Statement
Homework EquationsThe Attempt at a Solution
e) I know the temperature is lower in the transparent container but how do you represent this
Homework Statement
Homework EquationsThe Attempt at a Solution
[/B]
I am taking the free energy as the internal energy of the ideal gas.
Then the average internal energy per unit volume is ## \frac { 3 nk_B T } {2 } ##.
So, the correct option is (c).
Is this correct?
I could not find an easy or believable source on this question on the internet. Anyway, if I had a box (volume V) in space full of gas (density N) and a hole suddenly appeared, how long would it take all of the air to completely leave the box out into space? I would assume the air would be at...
In statistical mehcanics(pathria, 3rd edition), I have some questions for ideal fermi and bose gases. The textbook handles the approximation for z(=e^βµ) and nλ^3 (n=N/V, λ : thermal de Broglie wavelength). It considers the cases that z<<1, z~1, nλ^3~1,<<1,→0 and so on. In here, I am confused...
I was wondering and this might be a stupid question... I have approx. 200+ armatures with a GAS number stamped on them Like "GAS 3237". There are probably 20 different numbers or so. Where can I find a list of what these numbers are or mean?
I am using a Micromeretics ASAP2020 machine. The sample is ~25mg of reduced graphene oxide based film.
The problem is I am getting adsorption isotherms showing negative volumes of adsorbate (N2) entering the tube as P/P0 increases.
The sample was degassed prior to testing at 250°C for 3...
I'm currently studying Thermodynamic properties of a Fermi gas at the absolute zero temperature.
I get how the internal energy, pressure... etc of the gas are derived. For example, in computing the internal energy, one sums up all the energy of states weighted by its average occupation...
Homework Statement
A closed, thermally-insulated box contains one mole of an ideal monatomic gas G in thermodynamic equilibrium with blackbody radiation B. The total internal energy of the system is ##U=U_{G}+U_{B}##, where ##U_{G}## and ##U_{B} (\propto T^4)## are the energies of the ideal gas...
Homework Statement
The work done W by an expanding gas is calculated using W = pΔV. What must remain constant for this equation to be used?
a. The pressure of the expanding gas
b. The pressure of the surroundings
c. The temperature of the expanding gas
d. The temperature of the surroundings
e...
Homework Statement
Gas A at 125KPa (abs) is compressed isothermally and gas B at 100kPa(abs) is compressed isentropically (Y = 1.4). Which gas is more compressible?[/B]Homework Equations
Compressibilty = 1/bulk's modulus
Bulk's modulus = F/A/V/v or volume stress/volume strain
The Attempt at...
I have question regarding the (W = ∫Pdv) formula for the work done during the expansion of an ideal gas and the change in internal energy during the process. If we were to have a gas enclosed inside an insulated cylinder with a movable piston at one end with cross sectional area "a", I...
Homework Statement
Consider an ideal gas at 25.0 degrees Celsius and with a pressure of 1.00 atm.
a) What is the "number density" of the molecules, expressed as molecules per unit volume? (Cubic meter, cubic centimeter or liter)
b) What is the typical spacing between molecules in the gas? Of...
1. Two equal glass bulbs are connected by a narrow tube and the whole is initially filled with a gas at a temperature of T0 and pressure of P0. Then, one of the bulbs is immersed in a bath at a temperature, T1 and the other in a bath at a different temperature, T2. Show that in this problem, the...
Homework Statement
A gas effuses into a vacuum though a small hole of area A. Show that if the particles effused into an evacuated sphere and the particles condensed where they collided that there would be a uniform coating. (7.6 of Blundell and Blundell)
Homework Equations
Angular...
I am reading about gas discharge tubes and can't work out the types of energy and energy conversion that occurs in a gas discharge tube.
Initially before the tube is switched on you have an inert gas with kinetic energy.
As soon as the tube is switched on there is an an electric field between...
I've previously studied and used the k-epsilon turbulence model within Ansys to model water in a small stirred vessel. I am now interested in CFD models appropriate for modeling flue gas dispersion.
I'd like to know:
What additional considerations are required for modeling a gas as opposed to...
hello guys
i made a small crude tesla coil ( slayer exiter ) and i tried it on multiple gas tubes that i had
and i have been able to discharge neon , argon
but i have a question : how strong the electric field needed to discharge argon gas ?
During a thermodynamic process, the state variables of an ideal gas, measured in kPa, m3, and oC, varied in the following way:
P2 = 2P1
V2 = 3V1
T2 = 8T1
What is the temperature increase of the gas, T2 −T1 ?
I've been given an answer of 4780 and I'm not sure how to get there?
I'm currently in the process of selecting gas mixtures to calibrate a gas chromatograph. One of the gas mixtures I'm interested in has the following composition by percent volume:
methane (CH4): 95%
carbon dioxide (CO2): 1%
butane (C4H10): 1%
acetylene (C2H2): 1%
nitrogen (N2): 2%
The gas...
Assuming all gases in the combustion reaction of benzoic acid (C6H5COOH) behave ideally, what is the "exact" change in internal energy?
The context in which this question is being asked is after a calorimetry experiment. For all the intents and purposes of calorimetry, the change in internal...
Dear all,
I want to calculate thermodynamical properties of my molecule which I am calculating its thermodynamical properties of non-ideal part using Molecular dynamics. I need ideal gas state total energy, Cp, and Cv in several different temperatures. I am using opt+freq at B3lyp/6-311++G(d,p)...
The internal energy of monoatomic ideal gas is due to the kinetic energy of the molecules.
Using Boltzmann Maxwell distribution, it is calculated that the kinetic energy due to translational motion of gas molecules of an ideal gas depends only on the temperature.
In case of monoatomic gas, since...
Question:
The multiplicity of an ideal gas is given by g(U) = A.U3N/2, where U is the energy of the gas, A is a constant and N is the number of particles in the gas.
Prove that the energy of the gas given a temperature T is U = (3/2).N.kb.T
Attempts:
My first thought was to...
Homework Statement
The molar energy of a monatomic gas that obeys van der Waals' equation is given by
E=\frac{3}{2}RT - \frac{a}{V}
where V is the molar volume at temperature T and a is a constant.
Initially, one mole of such a gas is at temperature T_1 and occupies a volume V_1. The gas is...
Hi everyone,
I would like to know how to calculate the diameter of a pipe when we know the desired mass flow, the gas type, and the pressure at both end.
I have these requirements :
Gas : O2
Molecular weight : 0.032 [kg / mol]
Desired mass flow : 0.32 [kg / s]
Pressure in the gas tank : p1 =...
A few months ago there used to be some kind of gas leakage in the bedroom. Gas was almost odourless. I could detect the presence of gas only by aftereffects. They were :
1: I used to feel very sleepy. ( as if it was some anasthetic gas or chloroform)
2. Sometimes it used to feel like a breath...
Before anything, my apologies for offering such an elementary question about gas pressure. Any help would be appreciated.
1. Homework Statement
There are two chambers. One is 100 L, containing air at a pressure of 200 kPa. The other, joined to it, is 10 L and contains air at a pressure of 20...
Hi all,
maybe this is a silly question but I am a newbie in this particular design field. I'm working on a gas analysis system and I'm facing a mechanical design issue. The overall system is made of the electronic board (PCB) with a gas sensors array plus the signal conditioning electronics, a...
In the ideal gas law, the symbol n represents the number of moles of gas. My question is how, given a volume of a certain gas, one determines how many moles one has. My understanding is that a mole in this case denotes a quantity of particles. How does one determine how many moles one has...
Homework Statement
A mixture of hydrogen, carbon monoxide and carbon dioxide is being fed to a compressor at 2.0 bar and 25 C. The overall flow rate is 17.47 SCMS and its composition is 73.5 mol% H2, 13.7 mol% CO and the balance CO2 The compressor operates adiabatically and reversibly with a...
Hello Forum,
I'm looking to install a new chemical storage tank at my site. The tank itself is not rated for vacuum. We will have proper ventilation and nitrogen pumping into the tank to compensate when we are pumping out of the bottom.
However, I do want to include a pressure transmitter on...
Homework Statement
A constant volume gas thermometer contains a gas whose equation of state is
(p+\frac{a}{V^2_m})(V_m-b)=RT
and another, of identical construction, contains a different gas which obeys the ideal gas law, pV_m = RT. The thermometers are calibrated at the ice and steam points...
I am stuck on this concept in my physics book where the author claims that in a low density ionic gas the average of the time between collision and average of the time taken from last collision in ions is same. He further states that the average time to the next collision is same as the average...
Homework Statement
Two containers hold an ideal gas at the same temperature and pressure. Both containers hold the same type of gas but container B has twice the volume of container A.
The internal energy of the gas in container B is
(a) twice that for container A
(b) the same as that for...
Its generally a established that ammonia is present under the ice of many moons of gas giants. I guess many in the astronomy/astrobiologists community don't spend much time at home, as they would have noticed that ammonia is a household disinfectant. I understand we don't have any idea of the...
I can't understand why a gas passing through a porous plug experiences change in its pressure and why does the cooling or heating process depends upon the initial temperature
A 2 stage compressor has a final delivery/discharge pressure of 250 bar.
hydrogen is been compressed and stored in vessels.
The pressure in the storage vessel reaches the delivery pressure(i.e.250 bar) and the compressor is still running ( vessel has a safety pressure of 450 bar) and the...
Homework Statement
Argo, in its gas form, is insterted into a spinner, with a rhythm of 80.0 kg/min = 1.33 kg/s, temperature 800 C (= 1073.15 K), and pressure 1.50 MPa. It's decompressed adiabatically, and "escapes" the spinner with pressure 300 kPa.
a) Temperature when it "escapes" ?
b)...
Homework Statement
A cylinder is fitted with a piston, and the cylinder contains helium gas. The sides of the cylinder are adiabatic, impermeable, and rigid, but the bottom of the cylinder is thermally conductive, permeable to helium, and rigid. Through this permeable wall the system is in...
Homework Statement
A cylinder with a heavy ram/piston contains air at T = 300 K. Pi = 2.00 * 105 Pa, Vi = 0.350 m3, Mr = 28.9 g/mol & Cv = 5R/2
(a) What's the Molecular Specific Heat of an Ideal Gas, with a constant volume, computed at J/KgC ? (Cv)
(b) What's the mass of the air inside the...
Homework Statement
given:-fuel and air mass flow, measured mole ratios of exhaust composition y_i. Let's assume stoichiometric combustion so we have only CO2, H20 and N2 as products.
Homework Equations
Can EGR ratio be calculated from available data?
The Attempt at a Solution
I get result...
Something that routinely comes up as a problem at work is when we size flow projects for piping systems. We calculate pressure drop across a length of fixed diameter for compressible gasses, but we do not calculate pressure changes through an expansion or contraction with gas (for example...
How plausible would it be to store energy in the form of ionized gas? The idea is that a gas (I am assuming a noble gas would work best) would be ionized so that some outer electrons are removed from the atoms and then a positively charged Van de Graaff generator (or something that can fulfill...