What is Argon: Definition and 50 Discussions

Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv). Argon is the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust.
Nearly all of the argon in the Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most easily produced by stellar nucleosynthesis in supernovas.
The name "argon" is derived from the Greek word ἀργόν, neuter singular form of ἀργός meaning "lazy" or "inactive", as a reference to the fact that the element undergoes almost no chemical reactions. The complete octet (eight electrons) in the outer atomic shell makes argon stable and resistant to bonding with other elements. Its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990.
Argon is extracted industrially by the fractional distillation of liquid air. Argon is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily unreactive substances become reactive; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning. Argon is also used in incandescent, fluorescent lighting, and other gas-discharge tubes. Argon makes a distinctive blue-green gas laser. Argon is also used in fluorescent glow starters.

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  1. P

    Someone stole an argon cylinder today

    It is my fault. The cage/cabinet where all the cylinders are stored on the side of the building all have dial locks and I know it sounds really bad but my success rate with dial locks is close to zero. I was trying to swap out the 3/4 full argon cylinder for nitrogen but couldn't unlock it so I...
  2. R

    Get the mass of an argon atom and its molecular weight from Cv

    I don't see how isolate m or M. That is, how to get rid of <v^2> which is how I wrote the average of v2
  3. dreens

    I Argon or Dry N2 for venting a small Ultra High Vacuum chamber

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  4. Kathhhriine

    Thermal physics -- Converting the internal energy of argon atoms to temperature

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  5. Indula

    A Does molybdenum react with an Argon plasma powered by RF power?

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  6. P

    Boiling off Liquid Argon Using A High Powered Resistor

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  7. N

    Cubic Feet of Argon required to fill a tank under vacuum

    I have a tank that is 250 Cubic Feet. The tank is under vacuum (1x10-5 Torr).. which is actually 1.93368e-7 psia. How much Argon, in cubic feet, does it take to back-fill to atmosphere or 14.7 psia? Ambient temperature in tank is 90 degrees.
  8. S

    Pressurizing Argon Gas: Pump or Compressor Options?

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  9. doctor_cat

    Electrical conductivity of liquid argon

    Dear friends, does anyone know if there exists any study about electrical conductivity of liquid argon? Thank you in advance for any suggestion.
  10. P

    Why does liquid argon stop boiling after a while in dewar?

    When we fill a dewar or any other container with liquid argon (or liquid nitrogen), if I am correct, it sizzles because it is boiling. However, after we leave it inside for a few minutes, it stops. Does this happen because when you first pour it inside, the environment is of the liquid is much...
  11. S

    Thermodynamics - Temperature change of Argon

    Homework Statement The temperature of n = 19 mol of argon gas is increased from T1 = 21 oC by Q = 4.4 kJ heat transfer, while the gas pressure is kept constant. What is the new gas temperature in Celsius degrees? Homework Equations and as its a monoatomic gas I think this means that the...
  12. patric44

    Discharging argon gas with a homemade tesla coil

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  13. A

    I What is the type of field is exerted by argon plasma?

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  14. A

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  15. G

    A Paschen notation for electronic states of Argon atom

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  16. B

    [PoM] Cohesive energy in an argon crystal

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  17. M

    I What equations can help me understand Convectron gauges?

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  18. P

    Density computation for high temperature, low pressure argon

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  19. Stephanus

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    Dear PF Forum, Perhaps just yes/no answer would suffice. It's just out of curiosity and I can't find it on web. Or there are no answers :smile: Are there no noble gas compound? There are CH4, CO2, H2, O2 even O3 What about Helium, Argon, Neon? Are there really no compound with noble gas? If...
  20. R

    Helium vs Argon: Cost as shielding gases

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  21. G

    Fluorescent lamp: who emits UV?

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  22. F

    Flowmeter Impact from Changing Pressure

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  23. R

    Saha equation partition function for Argon?

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  24. Z

    Neutrino changes chlorine to argon

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  25. N

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  26. mesa

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  27. K

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  28. J

    Specific heat capacity of Argon dependence on temperature

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  29. L

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  30. A

    How does the radius of K+ compare to that of Ar?

    How is it that these two have the same electron level array (1s^22s^22p^63s^23p^6), but K+ has bigger radius than Ar? K+ has one more proton in its nuclei than Ar, so I would expect that if both have the same electron configuration - the one with more protons in its nuclei would have the...
  31. E

    Atomic density of argon in liquid and gas form

    Homework Statement Argon (atomic weight 40) exists as a monatomic gas at room temperature and pressure. The density of liquid argon is 1784 kg m−3. (a) Calculate the atomic density (atoms m−3) in liquid argon. (b) Calculate the atomic density (atoms m−3) in gaseous argon at a pressure...
  32. L

    Purify Argon gas by feeding it through heated titanium chips

    If a titanium heat treatment process is to be performed in argon that has been passed over heated Ti chips prior to entering the furnace, should the gettering Ti (the ones used for purifying the argon) be at a higher or lower temperature that the parts being heat treated? I know that a higher...
  33. O

    Help! 50% Helium and 50% Argon in a Sealed Container

    Hi all. Just got a question to ask, I'm slightly puzzled by it. Q. Say that you have a sealed container and you put in it 50% helium and 50% argon and you leave it for a few days. Because argon is heavier than helium, would the most of the helium rise to the top part of the container...
  34. M

    Calculating Thermal Conductivity & Mean Free Path of Argon

    Homework Statement obtain an expression for the thermal conductivity of a gas at ordinary pressures. The thermal conductivity of Argon (atomic weight 40) at STP (standard temp and pressure) is 1.6e-2 W/mK. Use this to calculate the mean free path in Argon at STP. Express the mean free path...
  35. E

    Why is argon better than a vacuum?

    Argon gas is used in a lightbulb because it's not reactive, whereas air is. But why is it better than a vacuum?
  36. B

    Argon radioactive decay dating

    Homework Statement The technique known as potassium-argon dating is used to date old lava flows. The potassium isotope 40K has a 1.28 billion year half-life and is naturally present as very low levels. 40K decays by beta emission into 40Ar. Argon is a gas, and there is no argon in flowing...
  37. L

    Why Do Argon Atoms in a Toroidal Box Show Unusually Large Positional Values?

    So I'm working on a problem where you have 100 argon atoms in a box that obey the Lennard Jones potential. We're using the Verlet method to calculate the position of each particle at the next time step. The issue I'm having has to do with our boundary conditions. We assume that atoms are on a...
  38. B

    The Entropy Change Argon in a non-isothermal process expansion.

    Homework Statement a) Calculate the entropy change when Argon, at 25oC and 0.101 MPa pressure, in a container of volume 0.5 litre is allowed to expand to 1.0 litre and is simultaneously heated to 100oC. b) Calculate the entropy change when the same initial sample is compressed to 0.05 litre and...
  39. H

    Calculating the Mean Free Path of Argon Atom

    Homework Statement Hi, I am not sure about the following question: (Q) Argon (atomic weight 40) exists as a monatomic gas at room temperature and pressure. The density of liquid argon is 1784kg/m^3. (a) Calculate the atomic density (atoms/m^3) in liquid argon *Done* (b) Hence...
  40. C

    Finding the number of atoms in 0.500 mol of Argon

    Question: How many atoms are there in 0.500 mol of Argon? No relevant equations do you take atomic molar mass (39.95) divided by 0.500 mol?
  41. M

    Argon sputtering onto Al(111)

    I'm attempting to research information on Ar+ sputtering on a sample of Al(111) in UHV (10-10mbar region) for the purpose of sample cleaning in conjunction with annealing, however I've hit a bit of a block. My main method of research has been to trawl through journal after journal to get...
  42. K

    What is the final pressure of argon gas after isochoric heating?

    Homework Statement 0.54 mol of argon gas is admitted to an evacuated 90 cm3 container at 10 o C. The gas then undergoes an isochoric heating to a temperature of 400 oC. What is the final pressure of the gas (in kPa)?Homework Equations PV = nRTThe Attempt at a Solution P(9.0x10-5 m3) = (.54...
  43. C

    Calculate Entropy of 1 mol of Argon (thermondynamics)

    Homework Statement Let the system be 1 mol or Argon at room temperature and atmospheric pressure. Calculate the entropy. Homework Equations The Attempt at a Solution
  44. T

    RMS speeds of helium and argon atoms

    i am having a bit of trouble with this question, and its not explained very clearly in our textbook... "what are the RMS speeds of helium an dargon in a gas at 1000 degrees C" any help would be greatly appreciated. physics is definitely not one of my strengths... =D cheers. KC
  45. B

    Radioactive Dating with Potassium Argon

    [SOLVED] Radioactive Dating with Potassium Argon Homework Statement The technique known as potassium-argon dating is used to date old lava flows. The potassium isotope ^{40}{\rm K} has a 1.28 billion year half-life and is naturally present at very low levels. ^{40}{\rm K} decays by beta...
  46. F

    Atom of Argon Charge: Help with Electron Work

    A little help with electron work Hi, I'm new and I was wondering if anyone could help me with this An atom of argon 37 Ar 18 is ionised by the removal of 2 orbiting electons. In the ion...
  47. Facial

    Exploring the Uses of Helium, Krypton, Argon & Neon in Incandescent Bulbs

    I have a question about helium : If it is the most inert substance, why isn't it used more than krypton or argon for high-temperature incandescent bulbs? I don't see neon in light bulbs too often either.
  48. S

    Calculating Weight of Argon in a Cylinder

    HI, Here's the question : A cylinder is fill with Argon (Ar) at 25 °C and 102,4 kPa with a total weight of 312,50 g. The dimension of the cylinder is 32,4 mm of diameter and 1,2162 m long. We remove Argon with a vacuum pump. What will be the total weight of the cylinder if the inside...
  49. E

    Adiabatic expansion of argon gas

    argon enters a turbine at a rate of 800 kg/min, a temp of 800C and a pressure of 1.5MPa. It expands adiabatically as it pushes on the turbine blades and exits at a pressure 300KPa. Calculate its temperature at exit. The equations I am working with are PV^(gamma)=constant and...
  50. P

    Argon vs. Helium for Window Insulation: Which is Better?

    We have to to a report in our chemisty class on heating houses. One aspect is the window. Our teacher says that good windows are filled with argon becuase they have a high specific heat. but looking on the internet I seem to find the specific heat of argon to be about 520 J/kgC which is...
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