John Cuthber

Congratulations! You have spotted your teacher's mistake. If you add an acid (and ammonium salts are acids, albeit weak ones) to a mixture of bases like carbonate and hydrogencarbonate, the acid will react with the strongest base first. For what it's worth if you did have carbonate and CO2 present they would react to give hydrogencarbonate Na2CO3 + H2O +CO2 --> 2 NaHCO3 A good way to embarrass the teacher would be to ask why nobody saw the bubbles of CO2 they said had been produced, but I'll let you decide if that's a good idea.

It really depends on the gas. In very cold weather you can work with liquid butane in a class if you want (and I've done it). Similarly in very hot weather (over about 35C) ether boils as soon as you open the bottle. For nitrogen and oxygen (and lots of others) you need to understand critical temperatures and pressures (above the critical temperature the gas will never condense to form a liquid no matter how high the pressure). For nitrogen you need to cool it below -147.1 and compress it to at least 33.5 atmospheres. Not really home experiment territory.

I don't see how a vacuum can, so to speak, "know" that it is moving in order to change its impedance accordingly. If I am running and I hit a tree I will become acutely aware of the relative velocity of the tree and me. How can I measure my speed with respect to a vacuum in order to allow for this when measuring its impedance, permittivity or permeability ?

Saryctos, you say "I think it would have been fine if it had not been played up so much." Er, maybe it's just me but I think that detaining people, many of whom have done no wrong and none of whom is technically guilty; without trial; indefinitely; at the whim of a bunch of soldiers and denying them any prospect of redress isn't "fine" in any set of circumstances, anywhere, ever. Playing it up, down or sideways really isn't the point. There is a very simple way to deal with this mess; find the people who did this and prosecute them for false arrest, false imprisonment, common assault, and so on. If it can be shown that the people who did this were strictly "only obeying orders" (there's a phrase nobody likes to hear) then prosecute whoever gave that order. If that means G.W. Bush does time in jail, good- at least he will have had a fair trial. That would restore the reputation of the law and it might persuade politicians to pay some heed to decent behaviour in future. As for "Just let them back into the country once the war is over?" When, exactly, will the "war on terror" be over, and who signs the armistice?

What's a FIFA? "Cricket, by the way, is a stupid sport, which doesn't hold a candle to baseball." That's a point open to debate. I understand that baseball is a variation on rounders- a game that, here in the UK, kids grow out of when they leave primary school at about 10 years old. However, to be fair, it didn't derive from rounders, we invented baseball first, then rounders. For those unfamiliar with cricket, an explanation the rules can be found here. http://en.wikipedia.org/wiki/Tea_towel_explanation_of_cricket So far as I am aware, there is no explanation of baseball.

I think it says a lot that the the "general stuff" topic is the only one with more posts than the "If you're planning on posting a message insulting us but don't want to bother with any thought or content, please do it in here. " topic. It may be a bit juvenile, but it's probably harmless.

It depends on what you mean by colour. Is "silver" a colour? If you put zinc, which is silver coloured ,into HCl it will dissolve to give zinc chloride, which is colourless (and hydrogen).

There's not any point bothering with a trial. Since the trial would be by millitary personel and their commander in chief has already stated that these are evil men, for the trial to find the poor sods anything but guilty would be insubordination. There's also a potential advantage to permitting evidence gained under torture. (just stay with me here for a minute) You can get anyone to say anything by torture so you can clearly get exactly the evidence you need to convict someone. It's easy, you just pick someone up and beat the s*** out of them until they say what you want them to. Then you get that "evidence" and use it in court. That means that the outcome of the trial will be exactly what the "authorities" want. Since we know all that, those who think evidence gained under torture has any validity must see that the authority is always right. If that's the case then you don't need the trial and you don't need the evidence. If you don't need the evidence you don't need to torture people to get it. In the long run, the acceptance of torture, and those things that follow from that acceptance, means that you don't need to torture anyone any more. I'm suprised Amnesty International are not campaigning for it right now. Of course there's the slight downside of the total lack of any sort of freedom and also of any accountabillity but surely that's a small price to pay for ensuring that torture is redundant. On the other hand you could accept that evidence gained by torture is not only a debasement of any legal process, but logically invalid. How did the US population get suckered into accepting this?

Sweet, or so I'm told; like methanol, chloroform, beryllium salts and lead salts. Of course, all of theses are poisonous so don't bother to try the experiment. No chemicals are harmless- it's always just a question of how harmful. I really wouldn't literally get hold of it since it will burn your fingers.

I'm not entirely sure but I seem to remember that, thanks to Mr Maxwell, you can calculate c from the permittivity and permeabillity of free space. I think it's the square root of 1/epsilon o Mu o (sorry I have't got the hang of Greek characters or subscript zeros here) Since these are porperties of a vacuum and a vaccum can't move it's not suprising that c is constant whether you are moving or not.

Do you mean this? http://en.wikipedia.org/wiki/Space_Shuttle_Columbia#Final_mission

Phenol stinks so I don't advise breathing in the vapour, it also burns the skin and you really don't want it in your eyes. However it's quite commonly used in industry and fairly dilute solutions of it are no worse to work with than lots of other laboratory chemicals. Why do you ask?

"is it possible " No.

"would the shiny side of tin foil work? " Yes.

You could measure the aluminium and work out how much sulphate the aluminium sulphate contributed. A titration using a pH meter as the "indicator" would, I think, give breakpoints corresponding to the titre of H2SO4, HSO4 and Al+++ so that would give quite a lot of information.

Heat gets transfered by convection, conduction and radiation. The first 2 need something to carry the heat so if you can trap a layer of vacuum (OK, I know that's an odd way of putting it) around the thing you want to keep cool you wil prevent heat reacching it by convection and conduction- that only leaves radiation to carry heat to the ice. If you wrap a mirror round it the radiant heat will be reflected away. You might want to look at the wiki article on vacuum flasks. OTOH, I don't think you are going to build a vacuum flask as a school project so I would concentrate on good insulation. I guess that insolent stuff is some sort of aerosol can full of foam. If so it's probably very good for this sort of thing. A couple of boxes, one inside the other and with the gap between them filled with foam (styrofoam works too) would be a very good start. (You need a "foam" lid too- obviously).

If this http://www.detectors.saint-gobain.com/Media/Documents/S0000000000000001004/SGC_SodiumIodideDataSheet_1005.pdf is typical (and I think it is) then the problem with NaI is that it emits lighht at about 415nm, that's only just visible so the eye won't be very sensitive to it. Even to get that you need to dope the NaI with thalium and that's not stuff you want to play with.

I'd really recommend that you look at some other metals too. Some small iron nails might be a good idea. Since it's a school science project you could ask them for advice on getting some other metals to try- zinc would be next on my list. It might also be interesting to try other drinks etc. I'm not sure I know anyone who drinks neat lemon juice, but I think it might give an interesting result. I will let you decide what your parents / school would think about wine and beer, but it would be perfectly valid science to test them too. A possible compromise would be to use low alcohol versions.

A blade is a good thing if it is a surgeon's scalpel and a bad thing if it is a murderer's dagger. There's nothing new about the fact that new discoveries can be used for good or bad things. Societies generally enact laws to prohibit daggers and permit scalpels. The same thing will happen with this technology.

It's OK, nobody ever looks at stuff posted on the net. You are just as safe as the person who posted about getting away with murder.

I don't seem to be the only one who thinks autocorrelation is a test for randomness. http://www.itl.nist.gov/div898/handbook/eda/section3/autocopl.htm You seem to have forgotten that what I originally wrote was "And, at the risk of arguing against myself, pi is random in a rather obscure sense. " Did you miss the last clause there? You wrote "I fail to see the distinction between a "clear" pattern and "no clear pattern". " Apparently, however many of us would see them as distinct. And you wrote "Making a new word and using it as an already existing work is bad for clarity." I presume that I shouldn't use the word random for anything non random. The trouble is that (arguably) nothing is random. "Pi has not been calculated, nor has it been proven to be infinite" True, three and a bit hasn't been proved to be infinite; probably because, since it's less than 4, it is clearly finite. It has been (I understand) proved to be transcendental so its decimal (or any other rational base) expansion is infinite. The proof is effectively the same as the impossibillity of squaring the circle. http://en.wikipedia.org/wiki/Squaring_the_circle From that I deduce that if you are looking for any finite series of digits in pi and you don't find it, it's because you have not finished looking yet. You asked "how do you know it simply doesn't go 77777777 at some point, having a finite number of fours?" I'm perfectly certain that it does go 77777777, not just at some point, but at an infinite number of points. It also has an infinite number of 4s (but not an infinite sequence of 4s because, to be infinite that bunch of 4s would need to be at the end, which would make pi rational which it isn't). At the risk of being really petty I should probably point out that you wrote "The first 4 will ALWAYS be followed by 1." and you objected to one of my comments because it would only be true in base 10. Dear Pot, thank you for you comment, best wishes Kettle. And btw, strictly, what I wrote would also be true in any finite, integer, base greater than 10. Personally, I like numerology; it's one of my favourite jokes. Anyway, the original posting 's idea sucks for any or all of the reasons put forward.

I'd start by thinking about how heat is transfered and what I could do to stop it.

Is it just me or does the idea that "I don't think the tendancy for scientists to lean towards the left has ANYTHING to due with natural philosophy. Simply stated, the left seems to put a lot more funding into non-military research than the right." misses the point that the right wing put a lot more money into research (military research) than the left wing puts into any research. If, as a scientist, I just want a government that spends lots on research, my best bet is to vote for the right wing and get a job working in military research. This could be taken as evidence that scientists are even more left wing than they look but some of us have been "paid off" by military research work. Personally I understand the efficiency of a free market for goods; Adam Smith worked out the basics of it a long time ago. However, being quite clever- which may be related to the fact that I'm a scientist or it may not, I can also see that, for example the care of the mentally ill is not something that the market can be expected to do well. There are other things (I gather the economists call them "public goods") which capitalism simply can't handle properly. That's why I'm not rabidly left wing or right wing; it's why I can take some sort of place in a debate on the matter, and it's also why I can see fault in either side getting too powerful- total freedom can be freedom to oppress

Just a thought, There's no question that there are differences between "black people" and "white people" whatever those terms mean. There is a question over the idea that one group (no matter how it is defined) is "superior" to another group. In my (undoccumented, unscientific and limited) experience ,colour of skin is a rather poor predictor of general inteligence however racist beliefs seem to be negatively correlated with inteligence.

I just wondered if liver with Chianti counts as meat and acid; but that's probably just my weird way of thinking.