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John Cuthber

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Everything posted by John Cuthber

  1. A practical relalisation of putting it an a spring and measurng the peiod of oscillation is given here. http://en.wikipedia.org/wiki/Quartz_crystal_microbalance These things are used in vacuo as often as not.
  2. "I talked to my professor " It might have been more helpful and more polite to do that before posting.
  3. Actually you could get repulsion if you were to use an alternating magnetic field. This would work for any conductive bullet. On the other hand the electromagetic coils and power supply would weigh so much that you would be better off hiding behind them.
  4. "CuFeS2 is a single compound a mixture of compounds." Pardon?
  5. Well, shadowact, you are half right. It is 10 vol, not 5. On the other hand have a look at eqn 5 in this http://www.ic.sunysb.edu/Class/che133/susb/susb035.pdf
  6. "it's an chromatography assay." Oh no it isn't.
  7. OK, 3% peroxide will generate about 5 times it's own volume of oxygen. That's plenty to see the reaction, even if it's a bit low for making the bulk gas. H2O2 is relatively stable in acid conditions so adding an acid won't do much to decompose it. Adding the peroxide solution to dried yeast will decompose it nicely. Adding it to potassium permanganate will do even better- you get twice as much oxygen gas for the same amount of peroxide. On the other hand, permanganates stain everything in sight and are relatively toxic. I'm not sure what Mr Sandman feels he has added to the thread.
  8. I think FeCuSO4 should be written as (Cu/Fe)SO4 ie a mixed Fe and Cu sulphate (both as 2+ ions). Made by oxidation of the similar mixed sulphide/ pyrites mineral. The most likely oxidising agent is a mixture of water and air. If I'm right about that then it's soluble in water. The sulphide isn't.
  9. Since the noble gases are perfectly able to form plasmas where they have less than the full complement of electrons that's not a reason for mentioning them here. On the other hand, they are as good an example of a plasma as any. "Does a gas become a plasma when an electrical current passes through it, or at a certain temperature? Both?" Well, both is probably the best answer. Any atom or molecule on its own in a gas might get ionised. It might be hit by another atom (or whatever) and lose an electron . It might get pulled apart by an electric field or it might get hit by radiation of some sort. In a flame some of the molecules are hot enough to be moving fast enough to chip electrons of molecules and atoms. Some of the maolecules in a candle flame are ionised so it is a plasma. On the other hand, most of the molecules are neutral, only a small frraction are ionised. A candle flame is, therefore, a weak plasma. In a neon lamp the initial ionisation can be caused by the electric field but it's sometimes caused by radiation. The normal background levels of radiation can sometimes do this. Whatever produces the first pair of charged particles- say an electron and a Ne+ ion, they are atracted to the electrodes in the lamp. The elelctron is drawn to the + electrode and the Ne+ ion to the - electrode. Usually, before they get to their destinations they plough into another atom of neon. If they are going fast enough they ionise this atom too. In this way you can readily ionise a lot of gas. After a while many of the atoms are ionised. Some of the ions get hit again and lose a second electron to give Ne++. Of course this is rarer than hitting an unionised atom so there are usually fewer Ne++ ions than Ne+ ions. Higher charged ions are also made, but these are rarer still. The atoms that get hit might not get ionised. They may just have the electrons knocked away from the nucleus into a higher orbital. When these electrons fall back they give out the excess energy as light. PPS you won't get Mg from Li that way, but you might get Be.
  10. Pioneer is talking nonsense saying "Gold has an almost a perfect balance between the proton's in the nucleus and the electrons in its orbitals, which makes gold very inert.". Every metal has exactly the same number of electrons round the nucleus as protons in it. Sodium for example has 11 protons and 11 electrons. It is hardly inert. I think the essence of the reason is very simple. Gold is soft so it can be peeled off easily and it's generally pretty inert so it doesn't bond to substrates like glass. IIRC silicone grease is also used for this sort of thing but it clearly depends on the context. What are you hoping to release from what?
  11. Everything is toxic, to some extent. Copper and iron compounds are unusual in that they are needed by the body in relatively large amounts ( a few grams of iron and a few centigrams of copper) but are quite toxic when present in excess. Anyway, you are right in thinking that the oxidation state of the copper and iron son't change, but look at the sulphur. As for the effect on the environment it will depend greatly on how the stuff is worked with. Obviously, if it's transported carefully in sealed trucks then there's less of a problem than if it's left to blow about the place.
  12. Perhaps we have different versions of the idea of floating, but "tied up with a bit of string" doesn't feature in mine.
  13. As far as I know lactose is only produced by female mammals to feed their young. That is its function. Bowels generally work just fine without it (except in the case of young mammals). Also lactose intolerance is rare where I live (in the UK) so I stand by my assertion.
  14. "Teachers have a professional responsibility to be respectful of their students beliefs. But firing over that is just lame." Imagine this scenario. OK Johnny, I think that 2+2 is 4 but if you want to believe that it's 5 that's just fine. I may have missed something but I thought the whole point of having a teacher was that the teacher knows stuff which is factually correct and teaches it to the kids.
  15. Am I missing some profound point, or is stuff like this "When we start to retranslate the life science data, if one assumes the H is essentially on its own, trying to its lower it electrophilic potential, in a world of highly electronegative atoms, who will try to shift the burden back, we end up with life molecules maintaining electrophilic potential. " the sort of gibberish I normally only see in shampoo adverts ("Here's the science bit"). Stuff like this "Water is a poor conductor of electrons. The O is too electronegative. The way water conducts potential is through the potential in the H. " leaves me wondering if Pioneer knows anything about ionic conduction as opposed to electron bands. I mean, sure water is a poor conductor of electrons but, since hydrogen is too, it can't be down to electronegativity. At the other end of the scale; silver is one of the least electropositive metals but it's the best conductor. Oh, and by the way, lightning is driven by the sun. Plenty of power there without invoking new exciting theories based on very little.
  16. That's not what usually happens where I'm from. Lactose is split into its 2 component monosaccarides and these are absorbed by the body and used as an energy source. Try lactulose http://en.wikipedia.org/wiki/Lactulose
  17. Can you supply any evidence for the claim that "This is due to the magnetic contributions having more of an impact than the charge"? As far as I'm aware the magnetic effects of H, H+ , Cl and Cl- can all generally be ignored. OK there's NMR spectroscopy but you need a magnetic feild that will just about pull your fillings out to get an energy difference that's markedly less than the typical thermal energy at room temperature. From the point of view of a positice test charge the H in HCl is at a higher electric potential than the Cl. From an equally arbitrarily chosen negative test charge's point of view the reverse is true.
  18. I think the problem is how do we know it's not, for example, NiCl3. That's not a trivial question so I don't think you are being stupid. The old answer was to make lots of compounds like chlorides, sulphates, oxides and whatever then analyse them to see how much of each component there was in each compound then try to work out how they could agree with each-other and with things like how much they depressed the freezing point of water when you made solutions of them and which ones crystalised in the same shapes. The current way is just to learn the valencies of the elements. This "if Ni has to 2 electrons to give away, it`ll need to Chlorines two accept them, one each." is a question rather than an answer. Why 2? why not 1 or 3? The answer is to do with things like lattice energy and ionisation potential.
  19. You might want to dilute the solution first. IIRC silver fluoride is soluble so titration with AgNO3 might work for HCl. Not sure if sulphate would interfere. You could try to ppt it with Ba(NO3)2 first but I think BaF2 is insoluble so that migt be tricky. The best way if you have access to the right equipment is to neutralise the stuff and measure the ions chromatographically. That way you don't need to drive off the HF as the vapour (and that's not a nice experiment btw). I think there's probably a way to do this by precipitations and or titrations on the stuff without making the nasty fumes. A titration against standard alkali will get the total acidity (and the H2SO4 concn if you are careful and lucky, the bisulphate ion should be distinguishable from the other acids if you use a pH meter while you titrate.) I think that MgF2 could be precipitated by adding MgNO3 and this could be filtered washed dried and weighed to give the HF concn. Then you could add Ba(NO3)2 to ppt BaSO4 to measure the H2SO4. Finally you could measure HCl by difference or by titrating with AgNO3. Good luck, and be careful with the HF.
  20. In order to secrete water and sebum.
  21. Hang on. Have a look at the part of the original post that I described as bollocks. This bit "Researchers at the Albert Einstein College of Medicine (AEC) have found evidence that certain fungi possess another talent beyond their ability to decompose matter: the capacity to use radioactivity as an energy source for making food and spurring their growth. " So I went on to point out that, "Firstly there is no evidence to support the idea that nuclear radiation is being used by the fungus as an energy source. This is a problem since that's what they are claiming. " and I get told "No, what they actually claimed was "Melanized fungal cells manifested increased growth relative to non-melanized cells after exposure to ionizing radiation, raising intriguing questions about a potential role for melanin in energy capture and utilization." What I should have said was that there was no plausible mechanism proposed. Extraordinary claims require extraordinary evidence. The plosone article says nothing about catalysis. It does say "Irradiated melanin manifested a 4-fold increase in its capacity to reduce NADH relative to non-irradiated melanin" which might just mean that radiation damaged melanin is more reactive. Big deal.
  22. Just as soon as you define what you mean by potential we might be able to answer the original question. "The H end needs to go outside the original molecule's electrons to lower its potential." doesn't seem to me to mean anything. OTOH Sayonara's point is valid enough that defining what you mean by potential may not contribute greatly to the world of chemistry.
  23. What would you expect to get by treating a primary alcohol, for example ethanol , with KMnO4 in acid?
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