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Everything posted by Caver451

  1. When you "create cold", you're really just "pumping heat". That is, moving heat from one place to another. Without moving parts, a peltier cooler is about your best bet, but while they are capable of creating quite a wide temperature differential--and some designs can even get to cryogenic temperatures--they can't generally move very much heat. If your intention is to create an air conditioner, it will work, but it won't be able to move enough heat fast enough to chill a room, for example. So, what are you up to? If you can give a few more details, I am sure we can come up with some hints. For example, you can do it without electricity if you only want cold for an hour or two. Dry ice can be used to cool a liquid which can then be pumped through a radiator. If you want really cold air, that is a good option. If on the other hand, you're just trying to make a simple and inexpensive air conditioner for a room, you can do what "they" did before air conditioners were invented: evaporative cooling. Take a regular fan, a pan of water and some strips of thick cloth. Soak the cloth and put the ends in the pan of water. When the fans blow across the cloth, it will cool the air as the water evaporates. It will also help increase humidity, if you live in a dry climate like I do. If you're just interested in cooling a small space, perhaps the size of a soda cooler, peltier is a great choice. Depending on ambient temperature, you can expect to cool a cubic foot or two down to about 45 F or so. I recommend just going to a department store and buying a premade cooler. I believe "Coleman" makes one. So, what is your application? We know you want to cool air, but to what temperature, on what scale, and for what purpose? -Caver
  2. The rock is a small piece of Uranium ore, which is approximately 2.5 cm long, 1.9 cm wide and 1.0 cm tall. I read around 900cpm at a distance of approximately 1cm. You don't really need the ore--but with such a small chamber, I was only catching one or two cosmic rays a minute, which was like watching paint dry. The 99.953% pure anhydrous isopropyl alcohol was purchased at "Fry's Electronics" in California. They don't ship, as far as I am aware. The manufacturer is MG Chemicals. Catalogue number 824-1 Litre. $7.99/liter. They appear to be a Canadian company. http://www.mgchemicals.com/ My research indicated that pure anhydrous isopropyl alcohol would work the best, and that the typical supermarket 70% "rubbing alcohol" would not. I assume it is because the water would interfere. I also heard that pure ethanol would work, but that is harder to get here. I do have some denatured ethyl alcohol which I am going to try. The dry ice I bought at the local grocery store. It was $1.00/pound. Pengiun brand. Over the next few days, I am going to try a few different configurations, though I admit I won't be using the Starbuck's cup. It was just to see if I could do it. I am going to try store bought 70% rubbing alcohol and denatured alcohol as well. As far as the tracks go, I admit in the pictures it is hard to see anything. It is also hard to pick out the tracks from reflections off the aluminum foil. It is much easier to see them as they happen. I will try to do a short video when I can borrow a video camera. I put arrows near them in the enclosed photo. They collapse pretty fast, so are very difficult to capture with the camera! -Caver
  3. I've always wanted to make a cloud chamber. They look like simple devices, and seemed pretty easy to make. As I usually do when a project like this pops into my cluttered brain, I started making a shopping list. Plexiglass sheets, epoxy, metal plate, ... hold on a second! Why am I making this so complex? This are simple devices. How simple can I make one? At that moment, I decided I was going to make a cloud chamber in a Starbuck's cup. For the uninitiated--and I can't imagine there are many--Starbuck's is a mega-coffee shop chain. Think $5 "gourmet" coffee. Unfortunately, I'm addicted to their black iced tea, and I usually have three or four a week. The iced tea comes in three sizes of cups, the largest 16cm tall with a 9.5cm diameter mouth. They are clear plastic. Could I actually make a cloud chamber in a Starbuck's cup? I stopped by Starbuck's on the way home, bought the largest iced tea, and then ducked into the grocery store to buy a few pounds of dry ice. As I was with my wife, it started the typical conversation: Wife: "Errr, what are you going to do with the dry ice?" Me: "Cloud chamber." Wife: "Oh." *shakes head* After consuming the iced tea, I rinsed the cup and dried it thoroughly. I then folded a small paper towel into a square just large enough to stuff into the bottom of the cup. I taped it in place and then poured in some 99.9% pure anhydrous isopropyl alcohol. The paper towel now saturated, I turned the cup upside down. Was pleasantly surprised that the tape held it in place. Next I cut a circle of aluminum foil slightly larger than the opening of the cup. I folded the edges against the cup and taped it in place, making sure the seal was airtight. Next I crushed some of the dry ice and placed the resulting snow into a small dish. The cup was then placed on the dry ice, aluminum foil side down. I turned off the lights and used a small flashlight to illuminate the bottom of the cup. After a few minutes, I started to get a little discouraged. There WAS a fine mist, but... BANG! A trail, plain as day, zipped along about a centimeter from the foil! A half minute later, another, and then another. You can imagine my excitement. I decided I needed a little more "umph", so I removed the foil, added a bit more alcohol to the paper towel. I then sealed a small sample of uranium ore in the cup, and sealed the foil back up. The effect was almost immediate, and absolutely dramatic. Dozens of small trails sped away from the sample. This continued for over 20 minutes, until the dry ice completely sublimed. I attempted to take pictures, but these trails are really tough to photograph! I did manage to get a few trails to photograph. Please find two attachments enclosed. One is of the completed cloud chamber, and the other is a close up of a few trails. I can't imagine a more simple cloud chamber. It's just a plastic starbucks cup, a paper towel, some aluminum foil, tape, dry ice and isopropyl alcohol. Took about two minutes to make, and worked like a charm! This must put me in the running for some sort of geek award. ;-) -Caver
  4. *chuckles* You can order small samples of uranium ore online. That will get the geiger counter hopping. You can also buy a container of potassium chloride "salt substitute" from the supermarket. That is also mildly radioactive. Remember, just making a geiger counter jump is easy--explaining why it is jumping is the hard part, and that is what is going to get you the grade. How about researching radiometric dating? It's an interesting topic, in my opinion, and since it isn't as "sexy" as other topics--fission reactors and such--it would probably be a pleasant surprise for your instructor. It's especially nice because it is generally non-political. -Caver
  5. My ferrofluid does indeed "blob", and the blob will follow your magnet anywhere. Tip: Put your magnet in a plastic bag when near ferrofluids, even the "blobbing" kind. Truuuust me. It IS possible to create ferrofluid that spikes at home, just not with the "add powdered magnetite to oil and pray" method. You need to actually synthesis the magnetite yourself, and introduce the surfactant (oleic acid, in my case) at the proper step in the synthesis. And you need to have the correct amount of carrier (the kerosene) or it won't spike. Kerosene can be found at any hardware store. Look in the solvent section--at my local Home Depot, it is stored with the paint thinners and other solvents. It is also used as fuel in kerosene heaters. Try to find it without dyes or perfumes. It's only a few dollars for more than you'll ever need. My magnet is a neodymium disk magnet. You can find neodymium magnets at any good science shop. The other thing you'll need is ferric chloride, which is about $8/liter. Again, more than you'll ever need. You can find it at any electronics hobbyist shop. It's used to etch circuit boards. Careful, it is toxic and it stains like crazy. You'll also need some steel wool to synthesis ferrous chloride from the ferric chloride. By at the grocery store (make sure it doesn't have soap already on it) or at the hardware store in the paint department. It's cheap. The finer you can find, the better. I used "#0000" grade wool, which is very fine for furniture refinishing. When you add the wool to the ferric chloride, it is an exothermal reaction which generates a good amount of heat--add a very tiny amount, mix until dissolved, repeat. I measured things out carefully, but ended up adding steel wool until there was no more ferric chloride to react with it. I recommend filtering the resulting ferrous chloride to remove the impurities introduced by the steel wool, as well as any left over steel wool. Ammonia is a cleaning supply which you can buy at the grocery store, drug store, home store, etc. Make sure it is not dyed and has no added perfumes. The cheap brands tend to be better in that regard. Have paper towels on hand, use rubber gloves (really!) and wear proper eye protection. There are other ways to make ferrofluid, but the one I gave the URL for uses the safest and easiest to obtain chemicals. Even so, it is still toxic, so please be careful. This is an "oil based" formula. There are water based formulas, but I wasn't able to find any that didn't use difficult to obtain and insanely toxic surfactants. One last tip: I suggest filtering your finished ferrofluid. Any magnetite which isn't in a death grip with the oleic acid is going to clump, will screw up your ferrofluid, and will make a major mess in your glassware. If you filter it, the clumping magnetite won't get through the filter paper, but the "good stuff" will flow right through. -Caver
  6. Caver451

    Cold liquid

    You know, you can mix dry ice with ethanol (which IS a polar solvent) and the resulting slurry will get you to around 195K. That extra 20K or so too much? Ethanol's melting point is about 160K. -Caver
  7. Hello! I know that beryllium acts as a neutron source when exposed to alpha radiation. What else exhibits this property? Are any other types of neutron reactions possible? For example, beta-neutron? Thank you! -Caver
  8. I don't know whether it HAS TO or not, but supposedly, if it "...has been activated with Silver at over 1500 degrees, and quenched with Copper salts..." it will glow when exposed to alpha. There is an outfit, "United Nuclear", which sells this stuff, among other things. They offer ZnS prepared as described above, $20/5g. http://www.unitednuclear.com/chem.htm Very bottom right corner. -Caver
  9. I have lead sheeting, and I'm in the process of building a proper hot box. With anything even remotely dangerous, I always err on the side of offering more respect than might be required. I would rather know I have more protection than I need, than think I have enough when I really don't. Besides, if anything, the box will be a conversation piece. I'm still debating whether or not I should remove the uranium oxide from the samples and then seal them up nice and secure like jdurg recommended. I'm beginning to lean towards DV8 2XL's advice and not bother removing the oxidation. It seems we've established that unless I seal the sample in a glass ampule under low pressure argon, I'm going to be struggling with the problem anyway. And the less contact with the highly toxic uranium oxide I have, the better. jdurg, I looked at your element collection... VERY nicely done! -Caver
  10. Sorry to bring up a slightly old post, but... First, I would suggest buying the proper supplies. They're pretty inexpensive, and since this is the first time you're doing something like this, you really want to remove as many unknowns as possible. In other words, concentrate on growing your bacteria, instead of wondering if your homemade supermarket agar is good or not. A good place to buy supplies like this is: http://www.hometrainingtools.com/catalog/life-science-biology/cat_microscopic-life.html I've ordered a few things from them in the past (in particular, some oleic acid for what turned out to be a very messy ferrofluid experiment) and they are pretty prompt with the shipping. Second, I strongly suggest, as other have as well, to read up and learn as much of the "why" as you can. We can tell you how to do it, but then you haven't learned anything except how to follow instructions. Knowing "why", instead of just "how", is most of the fun! One fantastic source of information is... your instructor at school! Believe me, nothing thrills a teacher more than a student showing a genuine interest and taking the time to ask them questions after school or after class. Just takes a few minutes, and believe me, asking your teacher for advice will almost certainly affect your grade for the better. Don't just ask your teacher "How do I do this?" Ask specific questions, "I want to use agar as my growing medium. What is the proper way to store, prepare and handle agar?" Your teacher may very well give you some, or help you prepare it. You don't need a big lab to grow bacteria, but you do need to learn the procedures for keeping things--including yourself--as sterile as possible. Washing your hands well, wearing a face mask and latex gloves, and keeping your work area clean go a long way. Give yourself plenty of time to get your equipment, and to run a few tests. Your first few attempts may fail in "amusing" ways, and it might take a few tries to get it right. Your failures are as important as your successes! Keep a log of exactly what you did, what happened, and why you believe it didn't work. I can't stress how important this is! How well you keep records of what you did is more important than bringing in a petri dish full of goop! Finally, there are a lot of different forums on this website. You might be able to get more specific information and advice on the Biology forums. Good luck! -Caver
  11. Wow, lot's of super good information, thanks everyone! DV8 2XL> I noticed, unfortunately! Can "how quickly" be quantified somehow? Would bare metal visibly blacken within seconds, or would it potentially take several minutes before the corrosion becomes visible? YT2095> I am sooo tempted to build a dry box, which would likely make it much easier. Especially when I decide to start swapping around samples! jdurg> Does the type of glass vial matter? If the metal is completely submerged in the mineral oil, what action causes the remaining air above the oil in a closed vial from getting to the metal? It sounds like you talk from some serious experience! I'm a bit new at this. I haven't started collecting the alkali metals yet, but it is definitely my favorite group and I am looking forward to starting. I just couldn't pass up on the uranium--it doesn't strike me as something that just pops up every day. Ironic, since so much of the stuff is produced... I want to get this whole mess of protecting my samples figured out before I start investing in elements I will end up having to replace later due to improper storage. Would building a dry box seem like a good idea? Any good sources of information on the technical "preservation" aspect of element collection available? How about "build your own" drybox design? Perhaps THAT is a separate thread! Thank you again for all of the incredible feedback so far! I think I found a new home! With interests ranging from several disciplines of physics, chemistry, and biology... I think I may well have found heaven! -Caver
  12. This sounds like what you're looking for. http://www.hometrainingtools.com/ Don't just "be careful", be "educated" in what you're doing. Chemistry can be exceptionally dangerous, even when you do know what you're doing. I suggest talking with your chemistry professor privately. He or she may be willing to supply the chemicals and expertise, if you show a genuine interest in learning. -Caver
  13. Hello! I have some samples of depleted uranium for my element collection. When the samples arrived, I became a bit concerned about how they were stored. Supposedly, under argon, but they have a relatively heavy layer of oxidation. I moved one of the two samples to a small glass vial under mineral oil (heavy, USP) to hopefully stop any further oxidation. The samples are each over 2 grams. Uranium oxide is much more toxic than uranium metal, so I'm a bit wary about trying to remove it from the samples. That said, any advice on doing this? Under mineral oil (of course!) with a brass or aluminum brush? I don't want to scratch the uranium metal underneath, so I should probably avoid steel brushes. Any pitfalls I can expect? Is USP grade heavy mineral oil acceptible for storage of the uranium metal? I can't imagine it wouldn't be, but I don't want to make the situation worse! I have no way of getting argon over the oil. Thank you for any advice or hints! I've included a small photo of one of the samples out of the packaging as I was weighing it. Notice the black oxide flaking off on the right side. -Caver
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