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John Cuthber

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Posts posted by John Cuthber

  1. Nevermind the rate of heat conduction of the metal and your hand. A thermometer reading the air temperature would read 30C and one reading the temperature of the metal would read 60C. The metal feels hotter because it is hotter. As DrP says, it's because the metal absorbs the radiation, but the air doesn't.

  2. How authentic does the story need to be?

    Does it matter if he kills himself with some poison with a made-up name? If so then you might want to use that idea- it avoids any question of you getting sued later when some dimwit tops themself and their distraught parents say that it's your fault.

    Also made-up poisons can have any set of symptoms and speed of action you like.

  3. But Xenon is inert. How does it react? I was under the (quite possibly mistaken) impression that the euphoria was simply due to the displacement of oxygen, much like asphyxiation/hypoxic euphoria.

     

    Good question. It's not just oxygen displacement or poeple wouldn't use N2O which is expensive when they could use N2 which is cheap.

    Last theory I heard was that it interacts with one of the gaba receptors. Since the receptors don't form covalent bonds it doesn't matter that the stuff is inert. Also that receptor must be about the most promiscuous receptor know. It accepts xenon, N2O, alcohol, chloroform - just about anything.

    SF6 is as potent greenhouse gas so there may be rules about what you can do with it and who you can sell it to.

  4. HCN may well be completely miscible with benzaldehyde in which case there's nothing much to force it into the water layer. It might work, or it might not.

    Sodium bicarbonate isn't a strong enough base to deprotonate HCN- it's a very weak acid.

    Sodium cyanide (if it's formed will react with benzaldehyde to form the cyanohydrin.

  5. I'd sooner work with SF6 than with just about any compound made from chlorine, bromine oxygen and selenium.

    Incidentally, it's not that potent an anaesthetic

    from

    http://linkinghub.elsevier.com/retrieve/pii/S152168960190179X

     

    "Although nitrous oxide (N2O) has been used routinely since the beginning of the modern era of anaesthesia, some of its adverse effects have only been discovered during the last decades. Thus there are some who advocate abandoning the use of N2O for anaesthesia. However, if the use of N2O is stopped, the anaesthetic regimen will have to be changed in order to substitute for a loss in potency. Thus, xenon has been suggested as a replacement for N2O. N2O and xenon share some clinical and physicochemical properties. For example, both of them are only weak anaesthetics but are potent analgesics. "

  6. I doubt you will find something that will record when you are exposed to an electromagnetic field that could be "harmful", because it is debatable whether they even are harmful -- nobody knows at what strength they might be.

     

    One simple experiment would be to build a large Faraday cage out of thick aluminum foil (preferably several layers) or fine metal mesh. All you do is build a wood box and wrap it in the foil (leaving a door to get in, of course), then step inside and seal it up. You would receive much reduced electromagnetic radiation inside the box, and you can then see if you actually feel better.

     

    Note that if you actually follow this advice you will suffocate.

    Mesh screened holes would be a good idea.

  7. They wouldn't get a chance due to the increased security there would be on board. i.e. under cover security guards with low velocity firearms. They would be shot as soon as they tried anything.

     

    As for crashing - well you could house the reactor in a larger version of the black box on flight recorder.

     

    You could put a nuclear reactor's worth of security on each flight, but I still think it would be easier to leave the reactor on the ground and have it generate energy to make "fuel" that could then be used to fly several conventional planes.

    I'm also a bit suprised that the "we need more guns to make it safer" idea came from the UK rather than the US.

  8. I Gues this may have been covered before, but if the earth expanded then, either by some miracle something would add exactly enough air to balance the expansion, or the atmosphere would get spread out thinner. It would therefore exert less pressure.

    However we know that atmospheric pressure has remained the same since it was first measured in about 1643.

    A 1% change in the earth's radius would give rise to a 2% change in the pressure (to a first order approximation) and we know that the pressure change has been much smaller- probably less than 0.1mmHg over the last couple of hundred years so the change is less than about 0.05 parts in 760 over 200 years. That's less than about 3 parts in ten million per year. How big an expansion is "happycoder" pretending there is?

  9. Uranium Thermite would be impossible since Uranium bonds so readily with oxygen that the heat created when it was formed would cause it to bind with atmospheric oxygen immediately. Plus, I'm not sure it would be thermondynamically favorable.

     

    What's the difference between very hot iron reacting with oxygen and very hot uranium reacting with oxygen? Since one works the other might.

    Also nobody said which uranium oxide to use I think this might work, though perhaps not to the metal.

    http://en.wikipedia.org/wiki/Uranyl_peroxide

    Of course there's the problem with spreading a nasty poison about the place too so I doubt anyone will do this.

  10. The advantage of using nuclear power for a military plane is that you don't need to refuel it often -it's just like a nulear powered aircraft carrier.

    However, even when we run out of fossil fuels, it's a dumb idea for a civilian plane.

    The shielding you need to make a reactor safe to be near is essentially too heavy to fly.

    It simply doesn't make sense to try.

    If you want to use nuclear power to run a plane, run the plane on hydrogen or methanol or some other "conventional" fuel made by using nuclear energy from a ground based reactor.

  11. No, they could equally well have said something like the eldest child is at the doctor's today or celebrated their birthday last week.

    You might need to know something about mathematicians. They only think it's a proper problem (ie worth asking) if there's a unique solution.

  12. I doubt that you can make vegetable dyes into the same sort of indicator paper that is made commercially. However you can use a number of comonly available materials to indicate acidity and alkalinity. Lots of berry like fruits have juices that change colour with pH. Grapes and blackberries work quite well. So does red cabbage. If I remember rightly onion skins go green in alkaline conditions. Turmeric contains curcumin which goes from yellowish to red when you add alkali.

    I think the best advice I can give is to try things.

  13. If I put my mind to it I could extract MSG from cheese. Probably the easiest way would be to leach it with water then extract the Na and the glutamate by ion chromatography- then recombine them.

  14. The machines convert one form of energy to another.

     

    It should be easy to explain why the machines will not work

     

    It is easy to explain why it won't work; it's a perpetual motion machine and they never work- it would break the law of conservation of energy.

     

     

    Incidentally, Am I right in thinking that a lot of houses in the US are made from timber rather than brick?

    If so might the "war on hurricanes" usefully be replaced by a "war on houses that blow down easily"?

  15. It's a fine answer and a good explanation.

    But is it right?

     

    I2 is more soluble in ethanol (about 21%) than in benzene (about 14%).

    I can't find the data for methanol, can anyone else?

     

    Incidentally, what colour is the solution of iodine in the 2 solvents?

    What colour is iodine vapour?

  16. Not entirely accurate. MSG is manufactured and added to food products. "Glutamate" is the carboxylate anion of glutamic acid, and while it's true that this is one of the products of MSG dissolving in water, there are other sources of glutamate, which is where the confusion arises. MSG is a sodium salt of glutamic acid, produced by fermentation of carbohydrate sources.

     

    To summarise MSG specifically is not found "naturally occurring" in food products, but glutamate (or glutamic acid) is.

     

    The idea of MSG being "bad" does not come just from the fact that it's an additive, but from a strange public resistance to the results of various studies linked to the MSG Controversy.

     

    It's not the sodium that gets the blame, its the glutamate. If it were ammonium or potassium glutamate the effect would be very much the same.

     

    If someone is affected by MSG they would be ill advised to eat parmesan cheese or soy sauce because the glutamate would get them without worrying what counter ion it had once had.

     

    For this assertion "MSG specifically is not found "naturally occurring" in food " to be true there would need to be some mechanism in food that prevented ion pair formation. Is there one?

     

    Incidentally, not everything that gets added to food has an E number. Only the things that have been tested and found to be "safe" (whatever that may mean) get E numbers.

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