jowrose

Hey Woelen, what kind of disposable battery are you talking about? And how would I go about getting one...

Yeah, I'm learning about both of these theories in a chemistry class right now and am a little confused, particularly by the molecular theory. The whole bonding and antibonding, sigma, pi, sigma-star, all that stuff can be a little intimidating. Well, to me at least...

Yeah, I'm not ever going to do that again. Sorry about the describing in too much detail, it never crossed my mind.

That last sentence, in retrospect, is extremely ironic. Here's a not-so-nice story... Once upon a time (about 2 hours ago), me and my friend went to the middle of the street with our knex/rocket car. I was videotaping (though I didn't get any very good footage), and my friend was watching. I lit the fuse, and we both backed up about 20 feet. The car moved forward a bit, and then with a massive BOOOOM it blew up. We only found about 10 percent of the knex car, along with a completely inside-out piece of copper piping. Industrial copper piping. Now, in true scientific fashion, I will analyze the results of my highly unscientific experiment. My rocket was composed of a piece of copper pipe (one end was sealed in the factory into a bullet-esque shape) and an end cap that had three very small holes drilled into it. The holes were I think 1/16 inch diameter (just a wee bit too small, methinks...). The cap was secured to the pipe fitting with nails. I drilled 2 holes into both the cap and pipe, and pounded a nail into each corresponding hole, securing the cap. When the pressure built up to, oh, a few hundred psi, the copper ruptured and let out all the gases with tremendous force. The knex car did not survive. Now, I know I'm a "kewl" or whatever you people like to call idiots like me who do stupid things. And I can say with certainty that I will never try what I did today ever again. It scared the hell out of me. I'll stick to smoke bombs and REAL scientific experiments.

I've always melted the mixture before, and have only had one accident (given it was with about 300 grams, and indoor no less...). What i'm thinking about now is trying to create a rocket with copper piping. I found this special piece at the home depot, and i'm going to fill it with the fuel and then secure a cap to the end. I'll drill a hole at the end, insert a wick, and see if it flies... I did a little testing by placing a rocket on this car made of Knex (yeah, it's not very scientific) and shooting it down my street, but the cap blew off with all the pressure so I'm going to find a better way to secure it.

All instructions for creating rocket fuel from KNO3 and sucrose call for the ingredients to be mixed in a ratio of 3:2 (KNO3:sucrose). Doing molar mass calcs, I found the molar ratio to be 9 mol KNO3 to 4 mol sucrose. Does that create different products from the equation you came up with, or just much messier products? If I was to mix the ingredients in the ratio given by your equation, would I get a better reaction (for rocket fuel, at least)?

Biochemistry would probably still be important, as genetic engineering does require a knowledge of the atomic structure of DNA, RNA, mRNA, proteins, etc.

Ok I was trying to come up with a balanced equation for the reaction between KNO3 and sucrose, C12H22O11. I think I figured out the relative amounts of reactants by using the generally accepted ratio (by weight) of 3 KNO3 to 2 Sucrose. 4 C12H22O11 + 9 KNO3 --> ? Or, if this is better; 8 C12H22O11 + 18 KNO3 --> ? I did some thinking as to possible products, and here's my best guess: 8 C12H22O11 + 18 KNO3 --> 87 C + 88 H2O + 18 KNO2 + 9CO2 My idea was that the H and O atoms from sucrose form water, leaving elemental carbon, some of which combines with oxygen from the decomposition of the KNO3, leaving KNO2. I considered NO2 as a product, but dismissed it because I didn't think K2O would form. I really don't know much about chemistry, so this is really just a somewhat educated guess. Any help is appreciated; I'm not asking anyone to come up with the whole reaction, just maybe a few hints as to what the products are. Thanks, john

Hey Augment, I'm a junior in high school as well, and facing a similar dilemma. I want to major in science, as you do (but maybe no biochem), and have been looking around for colleges with good science programs. I'm heading over to the east coast (I live near Chicago) to go take a look at colleges over spring break; I think we're looking at Dartmouth, Harvard, MIT, Rensselaer, Boston U and maybe one more. Rensselaer looks really nice, especially from a scientific viewpoint (they're really big on science, much like MIT). I'll try to remember to post anything interesting I find out in 2 weeks after I get back. -john

thanks.

Is there any way to get only the ions of a metal into a solution? Say you have a solution of CuCl2. Is there a way to remove the chloride ions, leaving aqueous Cu2+ without reducing the copper to copper metal?

Well it's really warm here in Chicago. Which is good in the sense that I'm not freezing whenever I walk outside, but bad in the sense that we'll never have a snow day. Man we haven't had one in a really long time.

Ok, I remember learning about partial fraction decomposition a while ago, and how it involved separating a fraction into the 2 fractions that existed before they were multiplied by a fraction of 1 to obtain identical denominators. However, I have forgotten how to do this, and I was wondering if someone could refresh my memory on how it's done. Thanks, john

Zeff can be crudely designated as the number of electrons in an atom minus the number of "core" electrons (aka all electrons except the valence ones). When using this calculation, it can be seen that Zeff (written as Z subscript "eff") increases along a period (not taking into acount transition metals). This means that atomic radius decreases along a period, and also makes the ionization energy (and electronegativity) a lot higher. However, there are some exceptions. Take O and N, for example. The I.E. of O is smaller than that of N because with N you are removing an electron from a half-filled p subshell, which is somewhat stable.

Then why, after pulling an all-nighter, will someone collapse physically? Are they lacking energy, or is it a symptom of mental exhaustion?

Perhaps we are just storing up a surplus of energy (ATP or whatnot) to use for the next day. Our digestive systems and metabolism and all that fun stuff is working all night, the energy has to go somewhere. The body, when functioning normally, uses more energy than it creates, so sleep is just catch-up time.

Rush Limbaugh states in his book "See, I Told You So," "-Despite the hysterics of a few pseudo-scientists, there is no reason to believe in global warming. -Mankind is not responsible for depleting the ozone layer. -The earth's ecosystem is not fragile, and humans are not capable of destroying it." Ok, this guy just cracks me up. But back to the question of whether we can save ourselves or not. As to the whole ozone problem, popular science did an article several months ago presenting several possible solutions to getting rid of the carbon dioxide. Several of them seemed like they would work well, but were very expensive. One of the most interesting (to me at least) ideas involved dumping tons of powdered iron into the anemic waters near antartica. The iron would spawn huge colonies of creatures (I'm not sure whether it was plankton, or krill, or what) that would "eat" tons and tons of carbon dioxide. The reason that this alternative is not being pursued is nobody knows what kinds of environmental ramifications such a strategy would create. So, yes, we are definitely capable of saving the earth, the dilemma is whether we will ever take the initiative. And people like Limbaugh will continue to live in their pleasantly utopian imaginary universes.

Ok I'm just wondering what the color of Cu(OH)2 is. I tried the experiment with CuCl2 and NaOH, and got a dark blue PPT. I tried it with CuSO4 and NaOH (excess of CuSO4), and I got a pale light blue PPT.

Depending on the teacher, you might get into some derivatives of functions, but that wouldn't be until the very end of the course. Basically it's just a review of algebra, geometry, and trig.

ah ok. I wondered what that meant. thanks.

So sulfuric acid has the structure H-O-O-S-O-O-H ?

Freethinker, not only does the group number tell the number of electrons in the outer shell, but it also tells you the element's outer subshell. The skinny rectangle at the far left of the periodic table (with the alkali and alkaline earth metals) has elements that end in the s subshell. Their period tells which level the subshell belongs to. e.g. magnesium ends in 3s2. Cross over the transition metals, and you get to the square box containing the metalloids and nonmetals. You'll notice that this section is 6 spaces wide, and it corresponds with all the p orbitals (with the exception of helium, which is 1s2). Again, the period of the element gives its element, so you can tell that chlorine ends in 3p5. The transition metals contain the d subshell, but the d subshell doesn't occur in level 3, as it should. This is because the 4s subshell is slightly less energetic than the 3d, so the electrons fill it first. You must remember this detail, and infer that Iron ends in 3d6 (not 4d6, as the period of iron would imply), but is preceded by 4s2. The f subshells don't begin in the periodic table until the 6th level, when they, in theory, should begin in the 4th. You can use the same method as in observing the d subshells of the transition metals. What is odd about determining the charges of the transition metals is that electrons are not most easily removed from their last energy shell (the d shell). Rather, they are drawn from the shell with the highest level number, which would be the preceding s subshell. So Iron doesn't have a charge of +6, but rather one of + 2 (as it loses the 4s electrons). Of course, most of the transition metals have several possible charges, but as a general rule the +2 is most common. I hope I got all that right, somebody correct me if I'm wrong.

Ok, I am frustratingly un-knowledgeable (is that a word?) when it comes to chemistry, but it all just fascinates me. So I decided to pick up a good book and hopefully learn some stuff (my high school class is dumb, we spent the whole 1st semester learning how to do calorimetry, rxn equations, simple stuff like that). I went to Barnes and Noble, and looked around their extensive sciences division (there were probably, oh, 5 different books) and picked up Linus Pauling's "General Chemistry." 300 or so pages into it, I have decided that it is an excellent text for anyone just getting into chemistry. Some of the stuff is WAY over my head (some of the equations are really out there), but for the most part the information is displayed in a logical and easy-to-understand manner. So my question is this: Does anyone else have any great chem books that they would recommend for students? Whether it be general chemistry, or in-depth analysis (I'm trying to find a good one on quantum theory), what are some of the best?

I know this post is somewhat going off on a tangent, but I figure this is the best place for it. I am currently without sulfuric acid, because I cannot find it anywhere. Every store I'm in, I check all the drain cleaners and household products for something with h2so4, to no avail. So I figured I'd make it myself, albeit in small quantities. I added some HCl to CuS04 (aq) and got a green solution (which I'm assuming is CuCl2 and H2SO4). I was trying to figure out a way to remove the CuCl2 from the solution. I think I could use a piece of lead, because lead chloride is insoluble, and then I could just filter out the acid, but I seem to have misplaced my lead supply (obtained from an airsoft gun...). Is there another way to do this? Could I just distill the solution?

So it's all about the Pauli exclusion principle? But since electrons fill all the way across a sublevel, and then double up, wouldn't they be magnetic if their last shell was, say, 3d5? or 4d5? or 4f7? Or is there something i'm missing?