Jump to content

John Cuthber

Resident Experts
  • Content Count

    17146
  • Joined

  • Last visited

  • Days Won

    30

Everything posted by John Cuthber

  1. The insides of drinks tins are varnished. Did you clean that off?
  2. Worse; the copper wire would act as the other electrode. The "battery" would be short circuited.
  3. John Cuthber

    immunity

    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.
  4. Same problems as before.
  5. 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
  6. 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.
  7. "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.
  8. 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.
  9. 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.
  10. 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
  11. 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.
  12. Please inform the couple of thousand or so people with references to "ice tyres" on the web.
  13. Iron (eg steel wool) and FeCl3 will also give FeCl2. This might be more use to you since you already have access to FeCl3.
  14. I thought that was where they shipped the "chese mountain" produced by the European common agricultural policy.
  15. 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.
  16. 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.
  17. 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?
  18. http://en.wikipedia.org/wiki/Barbiturates
  19. "But I think this particular person is trolling as in throwing your hook in the water while the boat is moving to try and snag something. " So, it's more trawling than trolling. Thanks for that; I suspect it will be the most useful aspect of this thread.
  20. "Perhaps it's just me that is missing something, but how come the conservation of matter is not followed in the equation?" It should be once the equation is balanced, that's the point. However, the equation given above simply doesn't make sense. If you react those starting materials you simply cannot get those products. There's nowhere for the chlorine to have come from. I guess it was just a hastilly made up example. There is a helpful fact. If you look at reactions like this you can sometimes balance them by looking at where the electrons go.
  21. I'm trying to enhance my knowledge of "netiquette" and internet terminology. Could someone let me know if this thread is an example of what they call "drive-by trolling" also known as, (so I understand) "troll and run"? As I see it, the other posibillity is that the original poster is a racist fool (which is probably tautology). Thanks in advance.
  22. In a way, its very easy. Take a mixture of, for example, copper sulphate and iron sulphate in water. Put a couple of platinum electrodes in it and put a current through the solution with a constant voltage. Initially copper (practically pure) will come out of solution until the concentration is so low that the potential needed to keep it plating out is higher than that needed to plate out iron. Then a mixture of the 2 will come out. (I think people who like Nernst's equation can put some numbers to this). What is much more difficult is to get any control over the relative amounts of copper and iron in the alloy.
  23. OK, but OH doesn't add to propene; it adds to the propyl cation which doesn't have any double bonds. The proton adds to the alkene to give this isopropyl cation (which is the more stable of the 2 possible cations). And that's why I was being condescending.
  24. I think he's more interested in diamagnetic levitation than those spinning toys. I have seen a web page with silver bullion bars being used to levitate a magnet (with the help of another magnet too). I'd sooner have to buy enough bismuth than buy enough silver. Also, it's fiddly with bismuth and silver is a lot less diamagnetic. I think you might want to practice with bismuth first.
  25. I don't hate religions particularly; I just dislike things that seem to lie to me.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.