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rthmjohn

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Everything posted by rthmjohn

  1. could you be a little more clear, like include the reaction equation?
  2. well, as yggdrasil said, there are many types of catalysts, but one example is in the formation of NH3 from N2 and H2. The catalyst used is platinum and rhodium. The catalyst in this instance causes the N2 and H2 to bind to it, weakening the bonds in each molecule. This either lowers the energy required to separate individual atoms or separates them entirely. The highly reactive H and N atoms are then form NH3 which leaves the catalyst.
  3. my bad, I didn't bother to look at his reasoning, just went straight to his answer
  4. Sounds like some of the other ones I 've heard which is why I didn't feel bad posting it...
  5. First off, here are the steps to balancing redox reactions in ACIDIC solution (apply each of the following steps to both the reduction and oxidation half reactions): 1. Balance the REACTING species (basically balance the ELEMENTS that undergo oxidation state change). 2. Balance the OXYGEN with H2O. 3. Balance HYDROGEN with PROTONS (H+) 4. Balance CHARGE with ELECTRONS (by charge I mean the net charge of each side of the reaction) 5. Find the Least Common Multiple of the number of ELECTRONS for both halves of the reaction. Combine the two half reactions, and the ELECTRONS MUST CANCEL OUT. Here's what I get for your reaction (and I'm pretty sure this is correct): Ox: CH3CH2OH + H2O --> CH3COOH + 4(H+) + 4e- Re: Cr2O7(2-) + 14(H+) + 6e- --> 2Cr(3+) + 7H2O The LCM of the number of electrons for the two half-reactions is 12, right? So we multiple the Ox: by 3 and the Re: by 2 to get: 3CH3CH2OH + 3H2O + 2Cr2O7(2-) + 28(H+) + 12e- --> 3CH3OOH + 12(H+) + 12e- + 4Cr(3+) + 14H2O Which can be simplified to: 3CH3CH2OH + 2Cr2O7(2-) + 16(H+) --> 3CH3OOH + 4Cr(3+) + 11H2O Hope this helps. Don't mean to be rude, but I think qwerty and neo are incorrect.
  6. My bad... Could you perhaps use something like lead bicarbonate or nitrate? The lead would form solid lead chloride, right?
  7. Interesting, I remember studying propogated growth in bio, but I never knew there were so many species that could do it. I think I read that there's a forest somewhere in the world that consists entirely of clones of the same tree or something to that effect.
  8. hmm... I don't think that'll work considering that both of the reactants are ionic and completely soluble in water. Basically, if you mix the two, you'll just have a solution of H+, Cl-, K+, and NO3- ions floating around so to speak. And I don't think that there's a way to separate both the Cl- AND K+ ions from the solution either. I suppose you could remove the Cl- by adding AgNO3 which would form a solid AgCl which could then be filtered, but I don't think there's an effective way of removing potassium ions.
  9. Well, air in a container can expand quite a bit. Using PV=nRT, which I'm sure you already know, I can give an example. So let's say you had a closed plastic bottle of capacity 20 mL and a fuse protruding from the top. You fill only 15 mL with flash powder so that the other 5 is just air (and close the container obviously). Let's say the initial T is around 24 degreesC (297 K) and the moles all the gasses in the container is about .05 mol. After we light the powder, the T almost instantaneously rises to, say, 260 degrees C (533 K, or 500 F, wich is about as hot as a household kitchen oven gets). Using PV=nRT (and using atm as the unit of P) we get P=[(.05 mol)(.082052)(533 K)]/.005L which means that P would equal 437 atm (437 times standard atmospheric pressure)! This very sharp rise to such an incredibly high pressure (combined with the high heat of reaction) creates a structural failure of the bottle which suddenly releases air (regardless of the small volume) molecules of very high KE creating pressure waves that translate into the loud report that you hear. Well, obviously, if you let the air in the vessel cool to thermal equilibrium, the pressure will also be the same as the pressure outside the vessel, thus, the air in the container won't want to rush out of the vessel
  10. So technically, if we were to create an ideal artificial environment with adequate sunlight, climate, nutrients, oxygen/carbon dioxide, and one free of harmful microbes, a particular species of a tree could live to be tens of thousands of years old (which, relative to the human lifespan, is pretty much like living forever)?
  11. I was trying to point out that humans are the only species that teach their population on the subject. But I guess the answers to my questions were quite obvious...
  12. I see. But don't many school systems include a sex ed course sometime in the late elementary/early middle school years? I know that at my elementary school, we had to learn ABOUT it and were taught not to do it simultaneously. In my highschool health class my teacher doesn't just say "DON'T HAVE SEX UNTIL YOU'RE MARRIED!!!" and neither does the health textbook. They teach about both abstinence and contraception keeping in mind that a large number of adolescents won't abstain until they're married. But that's aside from my point. If reproduction is innate in most species then wouldn't that mean that there may be a gene that can govern one's subliminal knowledge of HOW to reproduce? Is it possible that, regardless of how few instances there may be of this occurring, some few individuals of a species may not be able reproduce simply because of their lack of the instinctive knowledge of how? By teaching our children how or not to have sex (and I'm looking at this from a complete biological, not religious, standpoint) we are then negating the requirement for an inherent knowledge of how to reproduce because people are able to learn how externally. I'm also trying to point out that humans are the ONLY ones, as far as I know, who educate their population on sex/reproduction and that other species have to possess the instinct in order to reproduce.
  13. I don't think you understood me correctly. What I meant was that most people, regardless of their religious beliefs and whether they are discouraged from having sex, are taught about the physiology of sex at an early age (usually in the 5th grade). I'm asking whether the humans' knowledge of how to have sex is innate or if it has to be taught. Please read my thread clearly.
  14. i'm sorry, jdurg. I guess i must have misunderstood this site. http://members.aol.com/profchm/saltout.html There I was trying to sound all smart but really just making a fool out of myself
  15. Here's an interesting question, albeit a little obscure. I was wondering since people today are educated on the topic of human sexual reproduction/intercourse, either by their parents, school, or other source, if people today could even figure out how to reproduce on their own. I mean, I'm sure everyone registered at this forum was taught about sex/reproduction (either by a person or by a reference source) and didn't just figure it out on their own, right? I find it interesting because Neanderthals and Cro-Magnons and every other species before us obviously had to either figure it out on their own or instinctively possessed the knowledge (the latter being most plausable), but since most people today are taught about how to reproduce before they reach sexual maturity, do we even know if humans would figure it out on their own anymore? If you were to completely isolate a population of humans from any knowledge of sexual intercourse/reproduction, would they eventually figure it out on their own? Is it possible that there exists a gene that endows a person with the subliminal knowledge of how to reproduce? Is it possible that this gene is slowly being lost from the gene pool due to the human's ability to socially learn how to reproduce, thus allowing the people without the gene to still produce offspring? Any thoughts, anybody?
  16. As silly as it may sound, I had always thought that trees never die for some reason. Maybe it's because I would always hear about how many hundreds of years old the trees in the redwood forest are. My bio teacher told me that they do age, however, and that they do die eventually, even though it can take hundreds of years. Do trees also succumb to free radicals? Or is there some other cause? What gives them such an extensive lifespan?
  17. Does the powder itself go off with a loud report? I believe that in order to produce a report, the powder has to be confined to a closed container (preferably a tiny plastic bottle). The reaction of the powder itself releases LOTS of heat. This rapid change in heat in such a small container creates a tremendous rise in pressure that's almost instantaneous. Like RyanJ said, it is the air in the container that creates the blast.
  18. Wood's metal is a fascinating alloy composed of Bismuth, Cadmium, Tin and Lead with a melting temperature of only 158 degrees F... it melts in hot water... and solidifies as quickly at room temperature. It's also pretty light. An eight inch stick weighs only about a quarter of a pound!
  19. yup, on an equal mass basis the spiders thread is stronger than steel. It also depends on the species of spider. Some threads can even be twice as strong as steel. Check out this link: http://abcnews.go.com/Technology/story?id=97539&page=1
  20. yup, nothing... Have you heard it before?
  21. Are both testicles used for the same function? I was told once that one produces sperm and the other produces hormones, but that's probably wrong.
  22. Seeing as most of the threads here aren't all too entertaining, I don't feel so bad posting this one. I'm sure some of you have heard it before. It's more powerful than God, more evil than the devil, the poor have it, the rich need it, and if you eat it you die. WHAT IS IT?
  23. Ha ha... my teachers' teachers played this trick on them. Quite an old one... I will admit that the first time my teacher played this one on me, I did about half of the instructions before catching on.
  24. I figured nobody would want to attempt this problem. Our chemistry teacher gave it to us as a challenge, but no one in the class actually solved it. I was just hoping someone could explain the steps to answering it.
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