# Gaseous Oxygen = Paramagnetic?

#### Hessam

Ok, so i know that liquid oxygen is paramagnetic....

so is oxygen as well paramagnetic? (seems like a stupid question)

if yes/no... would then for instance a flame burn better if i were to hold a magnet next to it?

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#### Gokul43201

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Hessam said:
Ok, so i know that liquid oxygen is paramagnetic....

so is oxygen as well paramagnetic? (seems like a stupid question)
Yes, gaseous oxygen is paramagnetic too, for the same reason that liquid oxygen is - unpaired electrons.

However, you will not be able to observe this paramagnetism at anything but the highest possible fields (I'm only guessing that the required magnetic field is even achievable...but I'll have to do a calculation to make sure). The reason for this is that the kinetic energy of the gas molecules is so large that the effect of a magnetic field will be negligible in comparison. This is the reason why the popular demo is conducted with liquid oxygen - molecules in the liquid have much lower speeds (kinetic energies).

if yes/no... would then for instance a flame burn better if i were to hold a magnet next to it?
No, there really would be no effect. For one thing, I've explained that normal magnetic field will have little effect on molecules of gaseous oxygen. Even otherwise,why do you think that aligning the spins of the unpaired electrons should enhance the reaction rate with some hydrocarbon ?

#### Gokul43201

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Calculation :

1 Bohr magneton ~ $10^{-23}$ J/T
At 10T (which is really quite a huge magnetic field, typically requiring a superconducting magnet that costs tens of thousands of dollars), this gives an energy of ~ $10^{-22}$ J.

Typical thermal energies at room temperature are about kT ~ $4*10^{-21}$ J or about 40 times more than the magnetic energy.

#### umbrios

the only to see the effect would be to use a magnet similar to the ones that are used to confine/control plasma. but the power requiered and the cost of such a magnet are both extreamly high.

#### Gokul43201

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umbrios said:
the only to see the effect would be to use a magnet similar to the ones that are used to confine/control plasma. but the power requiered and the cost of such a magnet are both extreamly high.
Actually, I think plasma containment fields are only a few Tesla strong. The big magnet being built for MIT (supposedly hundreds of tons in weight) goes up to 13T or so. The more important quantity there is the total energy, not just the energy density.

My lab has a 16T magnet. Most NMR magnets are around 10T or so. The strongest persistent magnets are about 20 or 21T. Pulsed magnets get to much higher fields but for really short times. The National High Magnetic Field Labs in Florida and New Mexico have destructive pulsed magnets that go up to hendreds of Tesla but only for a couple of microseconds. But since this time is much larger than the typical relaxation time for air at STP, it should be possible to see an accumulation effect over this short time...just takes a camera with a really high shutter speed.

#### umbrios

Gokul43201 said:
Actually, I think plasma containment fields are only a few Tesla strong. The big magnet being built for MIT (supposedly hundreds of tons in weight) goes up to 13T or so. The more important quantity there is the total energy, not just the energy density.

My lab has a 16T magnet. Most NMR magnets are around 10T or so. The strongest persistent magnets are about 20 or 21T. Pulsed magnets get to much higher fields but for really short times. The National High Magnetic Field Labs in Florida and New Mexico have destructive pulsed magnets that go up to hendreds of Tesla but only for a couple of microseconds. But since this time is much larger than the typical relaxation time for air at STP, it should be possible to see an accumulation effect over this short time...just takes a camera with a really high shutter speed.
really? i thought it would have been much stronger than that. but i think that makes sense.

#### Hessam

No, there really would be no effect. For one thing, I've explained that normal magnetic field will have little effect on molecules of gaseous oxygen. Even otherwise,why do you think that aligning the spins of the unpaired electrons should enhance the reaction rate with some hydrocarbon ?
i meant this in terms of that air isnt 100% oxygen... thus if it is attracted to a magnet, then when i hold a magnet to a flame wouldnt the increased presence of the oxygen cause the flame to burn "better"?

however you answered that in regards to the previous question, thankyou

#### Gokul43201

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Gold Member
Okay, that may be possible (I thought you were thinking about electronic spins, for some reason) at extremely high fields, like I explained before (since nitrogen is diamagnetic). But even a powerful (NdFeB or SmCo5 type) magnet wont cut it.

#### osskall

liquid oxygen

hey, this is one thing I didn't think of: what about liquid oxygen, is it possible to attract O2(l) by magnets? Your answers almost seem to imply that...

#### Gokul43201

Staff Emeritus
Gold Member
osskall said:
hey, this is one thing I didn't think of: what about liquid oxygen, is it possible to attract O2(l) by magnets? Your answers almost seem to imply that...
Yes it is. In fact, this is commonly performed to demonstrate dia- and paramagnetism.

LN2 is diamgnetic, and will be repelled by a strong magnet. LO2 will be attracted.

#### Belipo

In short, can gaseous oxygen be removed from a particular area with the use of magnets?

For example: Could a magnet remove the oxygen from a 1X1X1 cube?

#### barkman

Another Question: I'm preparing density gradient columns (isopropanol/water). I am sonicating the two mixtures to get rid of dissolved gases. However, I notice that when I am mixing the solutions together to make the gradient, bubbles are forming on the magnetic stirbar. Is this an effect of paramegnetism or just ineffective sonication? If so, could I sonicate the solutions with magnets to elute more dissolved oxygen?

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No......

#### Tim_tx

Paramagnetism is the basis for the prefered oxygen sensing used in internal combustion engine emissions testing amoung other applications.

The sensor operates by applying a magnetic field transverse to the flow of room temperature gas in a capilary tube and measuring the restriction in flow versus a duplicate tube without the field applied. A heated thermistor or similar device is used for sensing the differential flow which is related to the concentration of oxygen in the sample flow.

An example of such a system is the Siemens Oxymat 5M.

Variations on this method are described in an article by RMA Kocache on page 199 of the book Techniques and Mechanisms in Gas Sensing Edited by PT Moseley, Jow Norris, and DE Williams. Published by Adam Hilger (IOP), NY, Copyright 1991.

#### BSE1808

"would then for instance a flame burn better if i were to hold a magnet next to it"?[/I]

Italian reports of a flame being affected by magnetism led Michael Faraday to discover in 1847 that a soap bubble filled with oxygen is attracted into a magnetic field whereas a soap bubble filled with nitrogen tends to move away from the field.

http://www.uh.edu/engines/epi1613.htm

This was only two years after Faraday had discovered the phenomena of diamagnetism and paramagnetism.

Whether the flame will burn better is another matter.

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