Paramagnetism of Oxygen

Oxygen gas is condensed into liquid form and then poured between the poles of a strong magnet so we can observe its paramagnetic properties.

We send O2 gas through a copper coil, which is then immersed in about 2 liters of liquid nitrogen (77 Kelvin, or minus 196 degrees Celsius). As the O2 travels through the coil it loses enough heat to change from a gas to a liquid, and that liquid is collected in a small pre-cooled Dewar. Liquid nitrogen is poured between the poles of the permanent magnet, but since its diamagnetic properties lead to only a very weak interaction with the field, it just sloshes through as if it were water. The liquid oxygen, on the other hand, sticks between the poles of the magnet until it boils away.

Because the oxygen molecule has an electronic structure that favors the non-cancellation of two of the electron spins, its net magnetic moment is free to point in the direction of an external magnetic field (just as a compass needle does). When enough of these moments are aligned, the material as a whole behaves like a single magnet. At room temperature only a small fraction of the moments are able to line up perfectly with the external field, but when oxygen is cooled and condensed into a liquid the effect is more noticeable.

For more details on our setup see:

[sheesulhassan]

Thank you for this cool demo... I was studying Molecular Orbital theory for my tomorrow's lecture and found this video... Gonna show this video to my students
thanks again <3 <3

[brainiac]

Nice magnet and nice video. The color of oxygen is just such a beautiful blue color...

[NickRoman]

I also liked seeing that liquid oxygen is blue.

[abdulmajeed-jbfg]

Who came here just after studying molecular orbital theory?

[Petrov]

BRAVO !!!'
• Molecular oxygen in the ground state is a bi-radical, containing two unpaired electrons in the outer shell (also known as a triplet state).
• Since the two single electrons have the same spin, oxygen can only react with one electron at a time and therefore it is not very reactive with the two electrons in a chemical bond

All organic compounds, including those that compose our body tissues, should react rapidly with air to form H2O, CO2, and N2 in an exothermic reaction.
Fortunately for us, however, this reaction is very, very slow.
• The reason for the unexpected stability of organic compounds in an oxygen atmosphere is that virtually all organic compounds, as well as H2O, CO2, and N2, have only paired electrons,
• whereas oxygen has two unpaired electrons.
Thus the reaction of O2 with organic compounds to give H2O, CO2, and N2 would require that at least one of the electrons on O2 change its spin during the reaction. This would require a large input of energy, an obstacle that chemists call a spin barrier.

Without the quantum rules that govern the predominantly two-electron chemistry of carbon, versus the one-electron behavior of oxygen, the world that we know and love could NOT exist.

[namir]

great video... it is one of my favorite demos. Note, If you used a white background you could really show off the pretty blue color of liquid oxygen.

[MhB]

I love how Echoes Live at Pompei is in the related videos. I highly suggest anyone who hasn't seen it to watch it now.

[johmcg]

The liquid nitrogen cooled the oxygen gas below its boiling point creating the liquid oxygen, so cool. That liquid nitrogen has a termperature of -320.4 degrees F. The liquid oxygen has a boiling point of -297.3 degrees F so it is liquid at -297.4 and degrees and lower. This is how the oxygen gas became a liquid. Very cool! Thank you.

[grandexandi]

I love these videos, but it frustrates me that they don't include any explanations at all for us who don't know anything about what's going on...

[waseebderang]

This is also done because Molecular orbital leaves two unpaired electrons in each of π• orbitals Hence, electronic configuration of molecular orbital accounts admirably for paramagnetic properties

[antaress]

I love this experiment. I'm so glad I found this channel. I watched all the uploaded videos for 1 afternoon. I studied in low budget university and we had only few experiments. Thank you so much for making these videos. This Universe never stops to amaze me.

And btw why the oxygen is blue in its liquid form?

[NatSciDemos]

@TehCthulhu combustion requires fuel, oxygen, and ignition, so by itself the liquid oxygen isn't flammable. on the other hand, because the oxygen is highly concentrated in liquid form, it will make any combustion happen more quickly (and violently).

[NatSciDemos]

@FTSinclair yes the induced magnetic moment is inversely proportional to the temperature.

[TheEmerhh]

I had been listening to some radio station and they played dubstep while I was watching this video. It sounds awesome!

[NatSciDemos]

the LN2 is 77 Kelvin. the "--" in the description is meant as an em-dash not a minus symbol.

[aravindaakash]

Watching with earphones, so satisfying

[Rayfer]

How amazing explanation. Very instructive. Helpfull for my job. Thanks you Very much.

[Indian-from-India]

Well done.  Thanks for uploading.  
Beautiful & powerful magnet.

[proggR]

The last scene really helped me see the 2D physics, thrown against a 3D space, vs a 4D model of time that I tbh believe relies on a 5+D model of perceptual/interactable time to make any sense. Each magnetic pole even in 2D creates the field that then interacts which each dimension above. Though forever I find myself asking... what would the 1D/monopole model look like? And could we ever surmise an experiment like this that so clearly presents it? Or at least a way to visualize it in a way that then helps underwrite broader physics?

Unanswered questions aside, thanks for this vid. Its great :)

[SmittenKitten]

Saw a picture in my textbook and had to look it up. Really cool 🤙