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John Cuthber

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Everything posted by John Cuthber

  1. RF heating seems a much better idea to me than light. Also, He is quite a good conductor, could you just heat the container and let the He carry the heat to whatever?
  2. Why mode lock the laser? Anyway, if someone can be bothered to do the arithmetic on the stefan radiation law http://en.wikipedia.org/wiki/Stefan-Boltzmann_law then they can see if a 2 inch square at 800C radiates more than 1KW (I suspect it might). If it does then you have no chance with just 1KW.
  3. Wills get overturned by the courts. The laws of libel, as another example, don't apply to the dead. Anyway if you want the simple moral answer it's easy. There is no reasone why anyone should ask for consent. You have finished with your organs when you are dead; how could you justify not donating them? Of course when the religious issues raisse their ugly heads it's another matter.
  4. I think the simple answer is that legally, when you are dead, you have no rights. It's also fair to say that the surviving family's desire not to use your organs to help others who can be helped (as oposed to you who cannot) may not be rational, but if it is their sincere belief, then you can hardly blame them for acting in accordance with their own beliefs.
  5. Lets face it; it wouldn't be a battery but it might make a decent hand warmer.
  6. Many soft drinks are acid enough to corrode a clean aluminium surface.
  7. Strictly speaking, they proved that the chimps are better at this task than university students rather than humans.
  8. The insides of drinks tins are varnished. Did you clean that off?
  9. Worse; the copper wire would act as the other electrode. The "battery" would be short circuited.
  10. John Cuthber


    Mainly because the cold virus keeps changing and so each time we meet it our imune system needs to lern about the new version so it can destroy it.
  11. Same problems as before.
  12. Remolding wood is called composting and planting seeds. It's not quick, but it's easy. Of couse there's always steaming the stuff and bending it too. Anyway, who needs to mold it to funny shapes? http://www.jthep-antiquities.co.uk/Bespoke%20Work/Examples/Wooden%20chain/Wooden%20chain.htm
  13. Could it be that the Iranian government know that the US and Russians have spy satelites capable of reading the newspaper headlines? perhaps they realise the the US and Russians will know perfectly well whether they have nuclear weapon technology or not. They lie about it, not to mislead the superpowers, nor even the smaller countries (who are likely to find out from ther former superpower allies), They are trying to fool their own people. To me this looks like a good bit of propaganda. "Look! We, your mighty government spit in the eye of the US aggressor- we will not bow to their demands that we don't make these bombs. We make them anyway!. The US says "Bluff! you never have made any." The Iranian Govt says "That's what you think". Everyone ends up believing what they want to. The people of Iran take pride in their country's abillity. The West relaxes thinking it's just those nutters bluffing again. The only way to find out would be to declare a nulcear war on Iran.
  14. "no, alu foil is actually surprisingly Pure, to at least 2 decimal places back! yeah I know, I was quite astonished to find this out too :)" Sure about that? Decimal places of what? http://www.enotes.com/how-products-encyclopedia/aluminum-foil http://www.key-to-metals.com/Article119.htm Also, in my experience it often leaves stuff behind when you dissolve it in alkali. It's possible that the blackening refered too in the first post is bits of other alloy elements trapped in a (mainly KI) matrix. Anyway the 2Cu++ + 4I- --> 2 CuI +I2 reaction is a classic for measuring Cu++ in solution. The problem is that you lose half the I as CuI. Peroxide and acid seems to be the method of choice for the amateur scientist but there are lots of possibilities.
  15. I'm sat on a wooden chair, held up by wooden floorboards. The roof that keeps the rain off me is slate (which is water proof) but held up by wooden bars. Similarly, the walls are stone because it's not going to rot any time soon. The house is a hundred years old and if I'm careful (ie I don't burn it down) it will outlast me.The computer in front of me is on a wooden table. I'm wearing a cotton shirt and jeans. OK, part of the reason that's a whole lot of cellulose is that it's cheap and easy to get, but surely part of it is that it's good at its job. What engineering material would you sugest I made the floor from? (please note Imight want to lift bits of it to lay power cables etc and I might want to fix carpets to it. Even with the carpets, I still want the stuff to be a fairly good thermal insulator. It needs to be strong enough that my book collection doesn't fall through the floor. I can put up with it flexing slightly under my weight but not much more than timber does. This should give it enogh elasticity to cope with thermal expansion as the house heats and cools without trying to bend the walls. Also, I want to be able to repair it if it gets damaged - preferably myself without expensive specialised tools. I think timber is pretty good stuff. BTW, re the question about bending a piece of wood back and to repeatedly. This experiment has been done with trees for thousands of years and with dead wood for hundreds as timber framed buildings have swung in the wind. It seems to do well enough.
  16. I'm sure that many people would agree that experiments on live animals just for the sake of a high school experiment are ethically questionable. That gets you off needing to use a real frog. Then something like this might just be possible. http://cgi.ebay.co.uk/Handmade-Foam-Fridge-Magnet-Frog-Design_W0QQitemZ250119069500QQihZ015QQcategoryZ20644QQcmdZViewItem Though it would still be a challenge.
  17. Copper atoms in a flame emit green light. Copper halide molecules (usually CuCl) emuit blue light. Emisions from S2 and HPO (a couple of unusual molecules- but you often get funny molecules in flames) are used for detecting S and P compounds in chemistry. http://www.shsu.edu/~chemistry/FPD/FPD.html
  18. No. The problem is that other reactions happen instead. Hydrolysis of the ester to the alcohol and acid would occur with both Clemmenson and Wolf Kishner conditions. The strong base conditions of the W-K reaction waould also produce condensation reactions.
  19. Please inform the couple of thousand or so people with references to "ice tyres" on the web.
  20. Iron (eg steel wool) and FeCl3 will also give FeCl2. This might be more use to you since you already have access to FeCl3.
  21. I thought that was where they shipped the "chese mountain" produced by the European common agricultural policy.
  22. I know you can get special tyres for snow and ice. I can't say if they work or not because I have't tried them. I also know that the local council busses use snow tyres in Winter. I presume the council looked at the costs and the savings from reduced accidents or lower insurance payments.
  23. A few metals that are not alkali or alkaline earth metals give colours too, copper is one example. Thalium is another but I don't think you will see that in a school lab. In principle there's no reason why non-metals cant be identified by a flame test. The blue colour of a bunsen flame is due to a bunch of non-metals (excited CO molecules iirc) emiting light. However, it happens that none of the non metals emits much light in the visible region. The blue colour of burning sulphur might be thought of as en exception I guess but I don't think it's very useful. If you are prepared to use some instrument rather than your eye to detect the light then a lot more chemicals can be identified by emision spectra.
  24. You probably want to keep it as sulphate because that isn't likely to interfere with the titration etc. You need to dissolve it in something- water is cheap and will dissolve the iron(II) sulphate but you don't need to use pure water if you think adding something to it would help. Iron (II) salts tend to oxidise in air. They do this slowly in acid conditions but quickly in alkaline conditions. Any thoughts?
  25. http://en.wikipedia.org/wiki/Barbiturates
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