John Cuthber

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.

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.

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.

Do you mean something like this? http://en.wikipedia.org/wiki/Dinorwig_power_station

I think most snake venoms are proteins, if you swallowed them you would digest them.

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.

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. "

Note that if you actually follow this advice you will suffocate. Mesh screened holes would be a good idea.

Melt it and electrolyse it is a fairly common school experiment.

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.

No, SO2 is denser than air.

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?

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.

I guess this arose from a different use of the word "homework".

Try adding a reducing agent. If you don't want Br2 formed you have to keep the solution alkaline.

Why bother to take the risk? You can leave the reactor on the ground.

Over mercury, by upward displacement of air or in a cylinder under pressure. Any more details?

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.

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.

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.

No, about a tenth of that. http://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/faq/lhc-energy-consumption.htm I'm still glad I don't have to pay the electricity bill.

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.

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"?

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?

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.