John Cuthber

The clue is in the question. It's empty so ...

There's the punch line of the old joke... "Three freshman-engineering students were sitting around talking between classes, when one brought up the question of who designed the human body. One of the students insisted that the human body must have been designed by an electrical engineer because of the perfection of the nerves and synapses. Another disagreed, and exclaimed that it had to have been a mechanical engineer who designed the human body. The system of levers and pulleys is ingenious. "No", the third student said, "you're both wrong. The human body was designed by an architect. Who else but an architect would have put a toxic waste line through a recreation area?"

Barely; that reaction usually goes the other way and there's a lot more water in the stomach than there is acid. I suspect that drinking enough alcohol to poison the bugs would poison the patient.

The heat needed to boil the water is the latent heat of vapourisation. There's a graph of how it varies with temperature here. http://en.wikipedia.org/wiki/File:Heat_of_Vaporization_(Benzene%2BAcetone%2BMethanol%2BWater).png The heat needed falls as the temperature is raised. If you raise the temperature to the critical point the heat needed to evaporate the water is zero because there's no difference between the "gas" and "liguid" phases.

Formic acid also exists and it can be made from insects. It's also rather more dangerous than most people expect- it burns skin rather better than conc HCl does.

If it works with tap water from a cup in a pan that's been used in any normak kitchen then there's goung to be enough dust to nucleate boiling; there's no superheating to speak of. It's a well known effect and has been for many years http://en.wikipedia.org/wiki/Leidenfrost_effect Incidentally I have seen lots of references to the idea that you can put a wet finger into molten lead without injury because of this effect. I have never seen anyone dumb enough to try it and I don't want to.

That's not fair! It's only the slow ones that can't escape.

"But wait! It "bends space!" " So do I.

Since it has already been proved that it cannot work the only outcome of challenging him to "prove it works" will be that he wastes more time and bandwidth. Trurl I can construct two totally different triangles with two sides of lengths 3 and 5. There isn't a unique solution so you cannot sensibly claim to have found "it". I'm beginning to wonder if Trurl can't spell "troll".

I think the traditional reply is "thank you for sharing that". ;-)

I'm not actually sure I explained anything, but I'd like to think I helped.

"If the whole world would just use the SI units, which need no conversion, we wouldn't have this discussion." With the information given you would not be able to answer the question in SI units. You can answer it if you use calories as the unit of energy. Incidentally, are you aware that plenty of us learned how to do this sort of thing using Joules or calories and because of that, could redo the calculations in foot poundals if needs be? Is this the forum for "people who can only do calculations if they are set out in exactly the right format and units"? Still you will be pleased to know that I won't be designing any bridges any time soon, though the last time I did it (a table really, but the maths is similar) I used SI units. Sadly, (this was in the days before Google) I only had a list of maximum permissible stresses and Young's moduli in PSI so I had to redo the calculation. I try to leave that sort of thing to civil engineers. BTW, is a civil engineer one who asks politely before building a bridge? Also, do you look forward to the day that McDonalds sell a "hectagrammer" or are you holding out for a Newtonner (with cheese)?

The heat radiated off into space was originally stored in the "moon" when you made it. Imagine I have a moon with a big rock on a table. A passing meteor knocks the rock off the table. The energy released is lost as heat by radiation (over time). No violation of anything- it just lost the energy I put in to lifting the rock onto the table in the first place. Imagine doing this with so many rocks that they wedged one-another up and didn't need the table.

Would you know how to answer this if they asked about ethanethiol rather than than cysteine? It's essentially the same problem.

Acetone does not mix with strong solutions of NaCl or MgSO4. I don't know about CoCl2 solution, because I have not tried it, but I would not expect them to mix. If there are two layers- one with a lot of water and one with a lot of acetone the experimental observations (a blue layer floating on a pink one) make sense.

I will use any unit of energy I like, including the barn yard atmosphere on a bad day. Converting to Joules just so you can divide by the same number again might be good pedantry, but I'm not sure it's helpful here. It's a pity that the Calorie and calorie get abused on food packaging but it's rare that the distinction actually troubles anyone. (Does anyone really think that a bar of chocolate might be only 1/10000 of a day's energy needs, or about enough energy for 100 days?) People use units that suit their personal experience and the work they are doing. There's not a lot of point trying to stop that so perhaps it's better to teach people how to convert from one unit to another and also to think about the magnitude of the answer and see if it's "just plain silly".

There really needs to be a fourth option in that poll called gobledygook or word salad or some such.

IIRC the first synthesis of anhydrous Cu(NO3)2 was from copper and liquid NO2 / N2O4 in ethyl acetate. Personally I'd rather not be there when someone made that mixture- it looks like aliquid explosive to me.

You don't need to do anything to oxygen to make a free radical. The triplet ground state has unpaired electrons, is paramagnetic, and reacts readily with other radicals. It already is a free radical. You can buy free radicals from chemical suppliers- galvinoxyl is one of the better known ones. https://www.sigmaaldrich.com/catalog/ProductDetail.do?N4=G307%7CALDRICH&N5=SEARCH_CONCAT_PNO%7CBRAND_KEY&F=SPEC〈=en_US

The oxidation of alcohols by permanganate or dichromate only works properly in the presence of a strong acid so that's not a very usefull way of making an acid. Lactic acid from sour milk is probably one of the easiest ones.

Re "The scalp stretches across the temples inside the skull." See a doctor (physician) urgently! Your head is inside out. The temples are (more or less) part of the skull and the scalp is definitely meant to be outside it.

We know that CFCs make it into the stratosphere so we know that, in the real world, such mixing does occur, albeit slowly.

It's a moot point if you you can kill a virus- depending on your definition of "life" viruses are not alive in the first place. On the other hand, even in popular scientific papers the word "kills" is used because it's quicker than "inactivates". TiO2 has some low lying electronic states into which electrons can be promoted by exposure to (near UV) light. These excited states can be used to degrade organic matter so, in the right circumstances, TiO2 in sunlight will kill the virus. What the advertisers seem to have overlooked is. It will also "kill" the fabric of the suit (I love built-in obsolescence) Sunlight kills viruses anyway. Any virus in lodged in the (black) fabric of the suit won't see any UV so it won't get killed. Ordinarilly, TiO2 is white- its biggest use is as a white pigment in paints etc. In order to get it to not look like your suit is covered in chalk dust the TiO2 must be in very small particles. I think the jury is still out on the scientific evidence for the safety of nonoparticulate TiO2 (though it is quite widely used in sunblock products and we haven't had an epidemic of deaths from it). I'd sooner take the risk of saving my money and still probably not getting 'flu.

121C is used because it's the boiling point of water at 1 atmosphere gauge pressure. It's an arbitrary choice, but that's where the funny looking number comes from.

You can buy alcoholic drinks with up to about 80% ABV without much difficulty (as long as you are over 18 of course)