Gas Definition and 1000 Threads

  1. R

    Thermodynamics Gas Mixture - Dew Point Temperature

    Homework Statement Only Number 1, not number 2 Homework Equations Dew Point Temperature T = Saturated Temperated at Vapor Pressure Partial Pressure = (mole fraction) x (Mixture Pressure) The Attempt at a Solution The dew point temperature is only dependent on the pressure of the water...
  2. Delta Force

    Helium Scarcity and Gas Cooled Reactors

    How much helium would a gas cooled reactor require for startup and loss replacement? Would helium's scarcity pose a major obstacle to widespread or long term adoption of it as a coolant for nuclear reactors?
  3. J

    Canister Ignition Protection: How Do Gas Containers Keep Flames from Spreading?

    So, this is just a simple question that crossed my mind. When say, a blowtorch or propane tank is ignited, how does the entire canister not go up in flames? How does the flame only stay on the outside and not burn through to the inside where the gas supply is? Will whatever principle this works...
  4. C

    Gas work -- Heating the gas in a cylinder with a weighted piston on top

    Homework Statement In the open cylindrical chamber is the piston of the total mass m. The initial air pressure inside the container is pa, the initial temperature T0. The initial height of the piston above the bottom h0. Now we start the gas supply heat to the moment when the piston reaches the...
  5. M

    MHB Which Gas Behaves Closest to an Ideal Gas?

    out of the gasses hydrogen,nitrogen,chlorine, and helium which shows behviour closest to an ideal gas.? ive been told the answer is helium because there is no attractive forces between helium atoms. would there not be van der waal forces though.? also would hydrogen just have as little...
  6. Robert James Liguori

    I Why does the Dry Air Gas Constant vary?

    I'm confused on why the dry air gas constant varies: Dry Air Gas Constant of 286.9 from The Engineering Toolbox Dry Air Gas Constant of 287.22 from https://www.physicsforums.com/ttp://www.peacesoftware.de/einigewerte/luft_e.html Dry Air Gas Constant of 287.05 from Brisbane Hot Air Ballooning...
  7. K

    Thermal expansion of liquid into gas void

    I have a question about thermal expansion of liquid into a gas void. Imagine a closed upright cylinder filled mostly with water – say 99%, and the remaining 1% is gas. Now imagine that you heat the cylinder and its contents. The water will expand by ΔV owing to thermal expansion. The gas...
  8. M

    Thermodynamics: Compression of an Adiabatic Gas

    Homework Statement Assume 1.500 mol of a monatomic ideal gas is compressed from 3.00 L to 1.00 L. a. If the initial and final temperature is 10.0 °C, what are the initial and final pressures (in atm)? b. How much work input (in kJ) is required if a reversible isothermal path at 10.0 °C is...
  9. F

    Gas Laws -- why calculate the mean square speed at 273K?

    Homework Statement Why is the formula ##p = \frac{1}{3}\rho<c^2>## used to calculate the mean square speed at 273K? Why 273K?
  10. M

    I Dissolved gas concentration in undersaturated liquid column

    Hi, In an enclosed system - of say Methane & water - in which the water column is sufficiently large to have significant pressure and some modest temperature difference due to gravity and geothermal effects, how would one calculate / predict the changing methane concentration (or partial...
  11. Weld Engineer

    Is the Flow Rate Across a Split Gas System Additive?

    If I have a 1/2" source hose with 60PSI and a Flow sensor then split to four 3/8" hoses with a flow rate limited to 30SCFH. Should I expect to have a 120SCFH flow rate across my flow sensor? The gas will be 90% Argon/10%CO2, but we could assume an Ideal Gas for this... Right? I understand...
  12. P

    Thermal motion of an ionised gas molecule in an electric field

    What I want to discuss here is what happens to the thermal velocity when an ionised gas molecule has been put into an electric field. Due to the charge (e) and potential difference (V), how much velocity has been gained by the ion can be calculated easily.eV = ½mv2 Where e is the charge of the...
  13. A

    How Does Changing Temperature and Pressure Affect Gas Density?

    Homework Statement In temperature 273 kelvin and pressure 1.013*10^5 Pa, the density of nitrogen is 1,25 kg/m3. Find the density of this gas in temperature 330 kelvin and pressure 1.40*10^5 Pa. T1=273 K; p1=1.013*10^5Pa; d1=1.25 kg/m3 T2=330 K; p2 =1.4*10^5 Pa. d2=? Homework Equations...
  14. rodv92

    Decreasing gas breakdown distance in a spark gap with UV

    Hello ! I am currently investigating a technique that would allow several spark gaps to breakdown synchronously in an enclosed but not hermetical cavity, flushed with N2 at 1atm and ~25°C My idea was to use "indirect" photoionization (basically a synthetic fused quartz UV flash discharge inside...
  15. Bonapartist

    Thermal energy problem: Gas expansion in cylinder

    Homework Statement A vertical heat-insulated cylinder is divided into two parts by a movable piston of mass m. Initially, the piston is held at rest. The top part is evacuated and the bottom part is filled with 1 mol of monatomic gas at temperature 300 K. After the piston is released and the...
  16. Z

    Pressure Equalization of X & Y Gas Bottles

    Homework Statement X and Y are two gas bottles that are connected by a tube that has negligible volume compared with the volume of each bottle. There is a valve in the tube that is initially closed. X has a volume of 2V and contains hydrogen at a pressure of p, Y has a volume V and contains...
  17. Z

    RMS speed in kinetic energy equation for gas

    I have been pondering. Why is it that we use the rms speed in the equation Ek = 1/2 m vrms2, as opposed to just the mean speed2
  18. S

    I Explain Graphs -- adiabatic Expansion of mono- di- and poly- gas

    "How it can be explained mathematically by dP/dV = -gammaP/V
  19. J

    Understanding the Different Forms of the Ideal Gas Law and Their Applications

    Hey I was hoping someone could be me a succinct method of knowing what form of the Ideal gas law I need to use and in particular the different R's associated with each form. Form my Thermodynamics class we use PV = nRT Pv = RT PV = mRT Little v being the specific volume (which changes the R...
  20. Lacplesis

    I Why Does Fire Not Travel Backwards in a Gas Hose During Ignition?

    Hi , a simple question arose in my head , why is that every time I have seen a hose attached to a gas tank being set on fire the fire always burns out of the end of he hose but the fire never travels backwards inside the hose back to the tank to explode it. the same I suppose happens to a...
  21. D

    Kinetic Theory - Mass on a piston

    Homework Statement A cylinder containing an ideal gas is in vertical position and has a piston of mass ##M## that is able to move up or down without friction (Fig. 13.2). If the temperature is increases, ...Fig (13.2) (a) both ##p## and ##V## of the gas will change. (b) only ##p## will...
  22. L

    Final temperature real gas behaving ideally

    Homework Statement Please consider a mixture of oxygen (1 mole), nitrogen (4 mole), and carbon dioxide (3 mole). The mixture was heated in a well - insulated vessel with 753 kJ. Determine the final temperature if the mixture is composed of real gases behaving ideally as described by Eq. 3.48...
  23. HethensEnd25

    An ideal gas closed system reversible process

    Homework Statement an Ideal gas at T = 70 C and 1 bar undergoes following reversible processes: a: Adiabatically compressed to 150 C b: then, cooled from 150 to 70 C at constant pressure c: finally, expanded isothermally to the original state (T=70 C and P = 1 bar) Homework Equations...
  24. S

    Entropy Change in Reversible vs Irreversible Gas Expansions

    Hello! I have this GRE question: In process 1, a monoatomic ideal gas is heated from temperature T to temperature 2T reversibly and at constant temperature. In process 2, a monoatomic ideal gas freely expands from V to 2V. Which is the correct relationship between the change in entropy ##\Delta...
  25. DaynaClarke

    Gas Compression Temperature Change

    Homework Statement "One way to heat a gas is to compress it. A gas at 1.00 atm at 25.0°C is compressed to one tenth of its original volume, and it reaches 40.0 atm pressure. What is its new temperature?" So, I have: P1 = 1 V1 = 1 T1 = 25 P2 = 40 V2 = 0.1 And I'm looking for T2 The question was...
  26. T

    Maximum temperature reached by gas in expansion

    Homework Statement 1 mole of ideal gas with internal energy U= 3/2 RT , expands from initial volume Vi = 1/10 Vo following the equation p=(− po / Vo ) V +po . Find (a) the highest temperature reached by the gas during the expansion and (b) the maximum amount of heat taken in by the gas...
  27. W

    What Is the Highest Temperature Reached in the Ideal Gas Cycle?

    Question (see attached diagram): PV diagram with 7.5 moles of ideal diatomic gas through cycle a, b and c. What is the highest temperature reached by the gas during the cycle? (multiple choice answers 180, 325, 208 and 100 C, i know answer is 208 C but I'm not getting it!) It is a PV diagram...
  28. D

    How to calculate the gas enthelpy in a particular pressure and temperatur?

    Hi All, Is there anybody who can help me with this question? Example: What is the enthalpy of CO2 in 200psig and 80deg.F? I have a software, but I'd like to see the calculation steps. Thanks Ding
  29. ervays

    Temperature, humidity and gas sealed box

    Hi, I'm working on my thesis and I need to calibrate some gas sensors that I'm building. I need controlled conditions(temp, RH and a known gas concentration) in order to calibrate the sensors. I'd love to know some idea to make a sealed box in which I trace and vary those parameter. I've...
  30. snoopies622

    Blackbody and gas molecule speed graphs look similar. Why?

    The graphs of intensity versus wavelength of blackbody radiation and of number of molecules versus speed in a gas look very similar to me. Is this just a coincidence? They seem like quite different phenomena.
  31. S

    I What is the formula for gas propane conversion?

    Is this answer is proper? Propane is a natural component of natural gas and is removed during the refining process. Most gas appliances can be converted from one fuel to the other by changing the burners on a stove or changing or adjusting a gas regulator located inside the appliance according...
  32. P

    Angular Frequency of a Piston with Ideal Gas

    Homework Statement A frictionless piston of mass m is a precise fit in the vertical cylindrical neck of a large container of volume V. The container is filled with an ideal gas and there is a vacuum above the piston. The cross-sectional area of the neck is A. Assuming that the pressure and...
  33. P

    How Fast Does Air Escape from a Pressurized Container?

    Suppose there is an enclosed container having air inside at say 4 barA pressure. Now, a hole has been made at one of the walls of the container and by another hole, air is continuously injecting inside so that the pressure wouldn't fall. Now, with what speed the air from the container will come...
  34. G

    Entropy of ideal gas: Volume it *has* or is *allowed* to have?

    Hi. If an ideal gas of ##N## particles is allowed to expand isothermically to double its initial volume, the entropy increase is $$\Delta S=N\cdot k_B \cdot \log\left(\frac{V_f}{V_i}\right)=N\cdot k_B \cdot \log\left(\frac{2V}{V}\right)=N\cdot k_B \cdot \log\left(2\right)\enspace .$$ This can...
  35. ScottAllenRauch

    Fluid Flow Loss Analysis Using Real Gas Properties

    I am trying to model fluid flow and losses through a component (e.g., pipe) using REAL GAS properties since 1) I have access to RefProp from NIST, and 2) I am dealing with refrigerants, which are far from ideal. I have seen nowhere an analysis of fluid flow losses (e.g., drag, friction...
  36. C

    Selecting a Valve for Natural Gas Flow

    Homework Statement A valve is required to regulate the flow of natural gas. Details of the gas are given in table below. It can be assumed that the pipe size and the valve size are the same [i.e. piping geometry does not have to be allowed for]. The chosen valve type is the V250 rotary ball...
  37. B

    Illuminating a Thyratron (mercury gas discharge)

    I found a thyratron tube at a yard sale recently and I want to build a circuit to heat the filament and illuminate the mercury vapor for purposes of building a novelty lamp. The filament is just 2.5VDC at 7 amps and I have a transformer for that. To light the vapor I will apply DC rectified...
  38. Ian Baughman

    Density of an ideal gas as a function of height

    Homework Statement If air has a density of ρ0 on the surface, calculate its density as a function of the height y for two scenarios: (a) the temperature is constant at T0; (b) the temperature decreases linearly T(y) = T0 − ay. Express your results using the given variables together the...
  39. D

    How might I liquefy small quantities of natural gas?

    Several undergraduate and graduate students and I are building a small engine powered by Compressed Natural Gas (CNG). It is a small and straightforward affair, similar to what is found in small equipment such as chainsaws and lawn mowers. I wanted to experiment with Liquefied Natural Gas (LNG)...
  40. G

    Gas Distribution: Temperature, MFP & More

    Diffusion of gases seems to follow normal distribution. I imagine deviations from the mean would depend on temperature, mean free path and speed of gas molecules. Any other? Cheers, Glenn
  41. R

    Terminology, pressure of gas in fluid (quick question)

    Would it be correct to say the following... CO2 for example can change the surface tension of water from 72 mN m−1 to 57 mN m−1 as its pressure changes from 1 to 11 bar. I'm used to dealing with concentrations, in fact I would like to change bar to volume percent if anyone has a free moment...
  42. BrainMan

    How can I calculate the work done in a gas compression problem?

    Homework Statement Homework Equations ΔEth = nCvΔT W = -∫ p dV pV = nRT The Attempt at a Solution I tried to find the total change in thermal energy by finding the temperature change. I first found the initial pressure P1 = nRT/V = 32464.4 Pa Then I solved for the final pressure...
  43. bluejay27

    I Ideal Gas Equation: Pressure not Proportional to Moles

    how is pressure not proportional to the number of moles?
  44. GabrieleCitossi

    B Solubility of Gases: Questions & Answers

    Hello. How are you my friends? Is there a gas that is completely not soluble in a liquid ? Thank you
  45. B

    B Energy of Ideal Gas: Internal E & Kinetic E

    Hi, When calculating the energy of an ideal gas we neglect the potential energy and calculate the kinetic energy using: K.E = 3 /2 n R T My question is why do we not consider the electrostatic energy of the gas? If I am trying to work out the internal energy of 1 mol of Radon, why do I...
  46. Siddharth Rajvanshi

    I Ideal Gas Law and Differentiation

    Is it possible to calculate the rate of change of n with respect to rate of change of Pressure and rate of change of Temperature with V unknown but constant by PV = nRT? Rate of change of Pressure and rate of change of temperature can be measured. R and V are constants.
  47. B

    Effect of an Inert Gas on Equilibrium

    Homework Statement N2O4(g) + energy <---> 2NO2(g) How are Keq and [N2O4] affected by the addition of Ne, an inert gas, in a container at constant volume and temperature. Keq [N2O4] a) no change/no change b) no change/ increases c) increases/decreases d) decreases/increases Homework...
  48. M

    What are the units for the Universal Gas Constant?

    Homework Statement Hello, I am not asking for the answer to an example, rather how the book got some numbers. The problem is an example from the book and shows me the solution but does not show the steps. Given: The compressed air tank has a volume of .84 ft^3. The temperature is 70 F and the...
  49. N

    Calculating Internal Energy & Temperature Change of Ideal Gas

    Homework Statement What is the change in internal energy (in Joules) of an ideal gas that does 4.675x10^5J of work, while 2.95x10^6J of heat is transferred into the system and 7.95x10^6J of heat is transferred from the system to the environment? Calculate the change in temperature of the two...
  50. ChloeYip

    Calculating Hydrogen Mass from Ideal Gas Law

    Homework Statement (introduction course of university physics) A 25- L container holds ideal hydrogen (H2) gas at a gauge pressure of 0.25 atm and a temperature of 0°C. What mass of hydrogen gas is in this container? The ATOMIC mass of hydrogen is 1.0 g/mol, the ideal gas constant is R =...
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