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  1. TeethWhitener

    Information on Sulfur hexafluoride?

    I’ve heard this is a myth perpetuated by more senior grad students to get their juniors to stand on their heads to remove residual SF6, but I really wouldn’t know anything about that.....:wink:
  2. TeethWhitener

    Information on Sulfur hexafluoride?

    SF6 is a low conductivity, inert gas used as a gas insulator in a lot of large-scale electrical applications. Maybe @anorlunda knows more about it. Fun fact about SF6: it’s much much heavier than air and non-toxic. As a result, if a large quantity is inhaled (NB—I AM NOT RECOMMENDING THIS), it...
  3. TeethWhitener

    A Two Particles on a Sphere

    https://arxiv.org/abs/1004.3641 If anyone’s interested in the state of the problem.
  4. TeethWhitener

    A Two Particles on a Sphere

    So write it out and show us where you get stuck. The reason I’m doing this is because it isn’t clear from your descriptions what, exactly, you’re having trouble with. If you can write out the Schrödinger equation for the problem but are having trouble understanding which terms make an...
  5. TeethWhitener

    A Two Particles on a Sphere

    Can you write down the Hamiltonian for two non-interacting particles on a sphere?
  6. TeethWhitener

    A Two Particles on a Sphere

    Have you tried to write down the Hamiltonian for either of the problems? Where are you getting stuck?
  7. TeethWhitener

    Chemical/Paint DIY Sabatier Reactor

    ...it almost sounds like you’re asking us not to help you. If all you want to do is fix carbon, just do it electrochemically. You can use a 9V battery and a platinum wire. If you want to do it efficiently, well...take a look at the work of the thousands of researchers trying to do just that. I...
  8. TeethWhitener

    Movie Classics that totally escape me

    I'll throw my hat in the ring and say that I just DID. NOT. GET. Rebel Without a Cause.
  9. TeethWhitener

    Chemical/Paint DIY Sabatier Reactor

    Also there's a ton of work being done on artificial photosynthesis/photoelectrochemical reduction of CO2 for fuel synthesis.
  10. TeethWhitener

    Chemical/Paint DIY Sabatier Reactor

    FYI Stuart Licht at GWU has done a lot of work in this direction: https://blogs.gwu.edu/slicht/solar-research/ They use molten carbonate cells to reduce CO2 to useful carbon products.
  11. TeethWhitener

    Worm Hole light years away and look at Earth through a giant telescope

    With an earth albedo of 0.3 in full sunlight, I get a photon per m2 (from the sun, reflected off earth) every 10 seconds or so at 100 light years. These are really crude approximations, though, so don't start building that telescope just yet.
  12. TeethWhitener

    Why does an alkoxide steal H from water?

    Yes, roughly. A better way to think about it might be to say that, for an alkoxide like tert-butyl, with a bunch of electron donating groups, the CO-H bond formed is stronger than the HO-H bond in water; thus the proton transfer process is energetically favorable. Again, there are secondary...
  13. TeethWhitener

    Worm Hole light years away and look at Earth through a giant telescope

    This is a fun little exercise. Given a blackbody temperature of the Earth of ~300K and the Earth's radius expressed in light years, you can calculate the number of photons from the earth impinging on a 1m2 telescope mirror per second at different distances. I calculate that at 100 light years...
  14. TeethWhitener

    Why does an alkoxide steal H from water?

    I'm assuming you mean hydroxide here. The equilibrium concentrations will be determined by 1) the initial concentrations, and 2) the equilibrium constant. You seem to be asking why the equilibrium constant should favor hydroxide and alcohol over alkoxide and water. It doesn't always, but...
  15. TeethWhitener

    B Hurricane physics

    Another reason it's more difficult to see the outflow than the inflow is that the outflowing air is much drier than the inflowing air (the warm humid surface air leaves most of its moisture behind in the storm as it cools and rises), so the outflow contains fewer clouds to show wind motion.
  16. TeethWhitener

    B Hurricane physics

    Does the gif in post 5 not work? The thick cumulonimbus layer is the false color portion of that image, whereas the cirrus outflow can be seen as the wispy black and white portion on the outer edges of the false color portion. The video you posted actually shows the same thing. At the very...
  17. TeethWhitener

    Why does an alkoxide steal H from water?

    Because alkoxides have somewhat higher pKa than water and usually you’re adding water to the reaction in a much much higher concentration than the alcohol. The equilibrium will favor the formation of alcohol over alkoxide.
  18. TeethWhitener

    Why does an alkoxide steal H from water?

    I’m not seeing what you’re talking about. The alkoxide in the video only abstracts one proton from the water, leaving a hydroxide ion. Edit: I’m talking about the events that happen at ~5:45 in the video.
  19. TeethWhitener

    B Hurricane physics

    Yes, the inflow is CCW and the outflow is CW (in the Northern Hemisphere). Here’s a gif of Dorian where it’s relatively easy to see the CCW rotation of the main body of the storm and the CW rotation of the upper level cirrus clouds...
  20. TeethWhitener

    Why does an alkoxide steal H from water?

    No, it’s an alkoxide. Alkoxides are quite basic, and if they’re in a fairly low concentration in water, they’ll end up being mostly protonated to form the alcohol as the conjugate acid product. That said, your intuition is right. Normally, a reduction like this would involve an acid workup...
  21. TeethWhitener

    Do these half-reactions have electrode potential that depends on pH?

    Ok, yes for the Cl2/Cl- couple specifically, there is no dependence on pH. You can see this on the Pourbaix diagram for chlorine as a horizontal line at low pH and high voltage (it's easier to see in the bromine diagram): But it's kind of a weird statement to make, because aqueous Cl2 is not...
  22. TeethWhitener

    Studying Why do I consistently receive low marks in basic science quizzes?

    Six months is not long enough to master anything. Six years is barely long enough to master anything. First, cut the self-pity. As long as you work hard and seek quality guidance, you'll be fine. Second, what makes you think learning QM will help you on a middle school biology quiz?
  23. TeethWhitener

    Do these half-reactions have electrode potential that depends on pH?

    Yes. You can google the Pourbaix diagrams for these species to find the dependence. This isn't quite true. At least for the halides, in water one of the stable species that is formed in highly oxidizing conditions is hypohalite, which entails reaction between the halide and water.
  24. TeethWhitener

    I Lattice specific heat, help understanding a passage in Ziman's book

    Energy is extensive (varies with system size), and dividing by another extensive quantity (volume) gives an intensive quantity. In this case, it’s volumetric heat capacity. Mass or molar heat capacity (where you divide the derivative of heat wrt temperature by mass or amount of substance) are...
  25. TeethWhitener

    A Electronic band structure of iron superconductor BaFe2As2

    Roald Hoffman wrote a phenomenal book on solid state physics starting from the point of view of atomic and molecular chemistry that helped me wrap my head around some of the concepts mentioned by other posters: https://www.amazon.com/dp/0471187100/?tag=pfamazon01-20
  26. TeethWhitener

    Specific Heat at High Temperatures

    JANAF tables are also good: https://janaf.nist.gov/
  27. TeethWhitener

    Studying How can I acquire physics and mathematics knowledge effectively?

    Practice practice practice practice practice. Get math and science books. Do the problems. All of them. If you get stumped, you can ask questions here. You're young, so you have lots of time that you can devote to this project. If this is something you really want to do, now is the best time to...
  28. TeethWhitener

    I Molecular vibrations

    Any N-particle system in 3 dimensions has 3N degrees of freedom. 3 are pure translations and 3 are pure rotations; hence the typical formula for molecules as having 3N-6 internal (vibrational) degrees of freedom. For a macroscopic solid, N is huge (a solid weighing a few grams will have nearly...
  29. TeethWhitener

    Ancient production of sulfuric acid

    This would depend on what you want to know. How would you test it?
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