hermanntrude

here's a useful link

that atmosphere would certainly kill any multi-celled organism on earth. Probably anything single-celled too. I think (but i'm not sure) that there are some bacteria that can handle methane, but probably not any that could handle the temperature that far from the sun. I think you chose a bad planet. I don't think you'll be able to describe this creature very easily unless you start just making stuff up. Hydrogen is highly flammable but you can breathe it if you're mad enough to try. it still wont give you oxygen, though, which you will need to stay alive. A few lungfuls and you'd start to pass out... although you'd die with a very amusingly squeaky voice. the same is true of helium except helium isnt flammable.

did you even read the other posts? I just offered a perfectly good way of predicting this behaviour.

reminds me of the whole liger/tigon thing

if you use it that frequently, you should have read the MSDS which would explain the hazards involved.

nice one. I was going to do the calculation too but decided against it. miles deep is still techinically correct... and i imagine the layer would be less thick as the hippos at the bottom (and the earth itself) would be crushed smaller by the weight of the hippos on top.

theo, the way to deal with ancient-minded idiots like the teachers who prohibit the use of wikipedia is to use wikipedia to get the original picture, and use the references cited in the articles as the quoted sources of information. I suspect that there might be a slight misunderstanding between you and your teachers, though. It's quite common for teachers to say something like "and don't go copying and pasting stuff from wikipedia", which makes the students think the teacher said "wikipedia is awful and must not be used for anything at all, ever". Now of course it probably isn't as distinct as that as you're not an idiot. My personal opinion is that as long as the article is properly referenced it's probably an excellent source of information and that anyone who doesn't understand that probably never wrote a decent research paper in their life and doesn't understand the very thing they're trying to forbid. Having said that i'd have a long careful think about it before using it for any political information, for instance.

A mole can be of anything. It could be a number of atoms or it could be a number of any other particle or even a number of hippopotamuses (although the earth would probably be coated miles deep in hippos if there were a mole of them). Anything can be made into a gas if you get them hot enough or put them in the right pressure environment. Many street lights contain gaseous sodium. You can tell because of the orange colour.

both answers are acceptable. the first answer shows the electronic configuration in the order the shells are filled up. The second shows the configuration in order of the values of n and l (not n plus l), which in this case is also the same as the order in which iron LOSES electrons. Weirdly, once the 4s subshell is full it becomes the outer subshell and when transition metals ionize, they lose their s electrons first. It's probably best to use whichever one your book uses to avoid confusion.

X diegone, This thread is OLD, and there are multiple threads already written about sulfuric acid. please only answer questions which actually NEED answering

X Diegone, the last response to this thread was in 2005. Back then I wasnt married and my baby wasnt even a glint in my eye. Please take note of what you're replying to. I imagine the sulfuric acid in question has been either disposed of or forgotten at the back of a cupboard somewhere by now.

weirdly, most teachers don't teach the n+l rule and just expect students to memorize the order of the subshells. It's a personal crusade of mine to show the n+l rule to the world.

OK but i was desperate. I had to smoke something!

the rule for which energy level gets filled first is called the "n + l" rule. I think you know that the "n" is just the number of the shell. "l" is the second quantum number, related to the subshell... s subshells have l=0, p have l=1, d have l=2 and so on. For any subshell, add up the values of n and l,then put them in the order you see them listed and you will find they go in order: 1s : n = 1, l = 0, n+l = 1 2s : n = 2, l = 0, n+l = 2 2p : n = 2, l = 1, n+l = 3 3s : n = 3, l = 0, n+l = 3 Notice that the 3s and 2p subshells both have the same value of n+l, but the 2p goes first because it has a lower value of n. This rule is important as a tie-breaker when subshells have the same values of n+l. 3p: n = 3, l = 1, n+l = 4 4s: n = 4, l = 0, n+l = 4 3d: n = 3, l = 2, n+l = 5 4p: n = 4, l = 1, n+l = 5 5s: n = 5, l = 0, n+l = 5 4d: n = 4, l = 2, n+l = 6 5p: n = 5, l = 1, n+l = 6 6s: n = 6, l = 0, n+l = 6 4f: n = 4, l = 3, n+l = 7 5d: n = 5, l = 2, n+l = 7 6p: n = 6, l = 1, n+l = 7 7s: n = 7, l = 0, n+l = 7 5f: n = 5, l = 3, n+l = 8 6d: n = 6, l = 2, n+l = 8 7p: n = 7, l = 1, n+l = 8 8s: n = 8, l = 0, n+l = 8 5g: n = 5, l = 4, n+l = 9 etc etc etc

bonds can be formed in two ways (for non-metallic substances). Particularly, in a molecule, bonding occurs by the sharing of electrons, as you said (known as a covalent bond). However, the electrons are still only on two atoms and still not moving around the entire molecule. In benzene, there are six atoms in a ring, and some of the electrons can move all the way around the ring as many times as they like. This is what makes benzene so unusual.

cameron I have to say i really commend your curiosity. You're asking some questions which can't be easily answered. The answer to this one would take at least a page, and a full answer would take an entire degree. How old are you? perhaps you're going to college or university soon? you might want to think about taking a chemistry course or even an entire program

you're going about this all wrong. MgSO4 and Cu are quite happy the way they are, and electrolysis isn't magic. it can be quite complex. I'd guess that what you made was copper sulfate but you also probably generated a lot of hydrogen and oxygen and perhaps also changed the pH of the solution. Copper salts often change colour depending on what else is around. copper sulfate is surprisingly difficult to make, but the easiest (although certainly not a safe method) involves the use of both nitric and sulfuric acids and copper. You will only be able to use this method if you have a fume hood, and a proper laboratory method. there may be a viable electrochemical method but sticking some copper and "something with a sulfate ion in it" in a beaker and ramming it with as many volts as possible is going to be complicated

benzene is the most common example of a molecule of a type known as aromatic. This doesnt really mean they're smelly, although many of them are. they have an unusual way of keeping their electrons. In most molecules, the electrons of one atom always stay on that atom. In benzene, some of the atoms are able to move from atom to atom. This gives it a higher-than-expected stability, and some other quite interesting properties.

well for a start, you need to write the equation. Also remember that Kw is simply Kc for that particular equation. Also remember that the concentration of water doesn't appear in the equilibrium expression because it's a pure liquid. The perfect answer would include your first sentence (which is very correct), followed by the equation for the equilibrium, with the Kw beside it. You can then say that Kw = [H3O+][OH-] = 1 x 10^-14, and that since the [H3O+] and [OH-] should be equal, you can say that the [H3O+] is equal to 1 x 10^-7 and therefore the pH is 7. You should also add a note that the above is only true at 25°C. Kw, like any equilibrium constant, is dependant on temperature. In fact, the pH AND the pOH of water at higher temperatures are BOTH less than 7, because the autoionization is endothermic.

NO. it doesn't always work out the same. You have to follow these steps: -draw out the equation -draw out the ICE table -write out the Ka expression in terms of x -check to see if the assumption is likely to work, if it is, make the assumption, get x and check to see if the assumption gave an error of less than 5% -if the assumption doesnt work, check to see if it's a perfect square, and if not, use the quadratic formula. There is no quick way around this, but if you learn the method it can be quite easy with practice.

Well, there's not always a simple way, but sometimes there's an easier way than solving a quadratic, although you'll need to be able to do both, and both methods involve the ICE table. For instance, if you're asked to find the pH of a 1M solution of a weak acid with a Ka of 1 x 10^-10, you can plug into your ice table like this: Acid + Water <=> Hydronium + base I 1M - 0 0 C -x - +x +x E 1-x - x x Notice we ignore the water because it is a pure liquid and has an activity of 1. Now you can plug in your algebraic values for concentrations at equilibrium into your equilibrium constant expression: [math]Ka = 1 \times 10^{-10}[/math] = [math]\frac{x^2}{1-x}[/math] Now you can see that since our Ka is so tiny (one ten billionth), the chances are that subtracting it from 1 is going to give us approximately 1. This means we can make a simplification: [math]Ka = 1 \times 10^{-10}[/math] = [math]\frac{x^2}{1-x}\approx \frac{x^2}{1}[/math] And so in this case we can simply take the square root of the Ka and that will give us a value for x, from which we can calculate the pH. [math] x = \sqrt{1 \times 10^{-10}} = 1 \times 10^{-5}[/math] This approximation only works when the value of Ka is very small compared to the initial concentration (in this case 1M). You must ALWAYS plug your value of x BACK into the equilibrium expression to check how close it comes to the real value of Ka: Assumption check: [math]\frac{x^2}{1-x} = \frac{(1 \times 10^{-5})^2}{1-(1 \times 10^{-5})} = 1.00001 \times 10^{-10}[/math] So you see our value for Ka calculated using the assumption is within 0.001% of the actual value, which means the assumption is valid. The rule is that it should be within 5% of the actual value. If it isn't, then you MUST solve the quadratic. It doesn't always mean you have to use the quadratic formula, though. Sometimes, although not usually when working with acids and bases, you'll get a perfect square, ie something like this: Ka = [math]\frac{x^2}{(x-0.1)^2}[/math], in which case you can safely take the square root of both sides. In some cases (perhaps not in your course), you'll find even higher order equations, cubic, quartic or worse. In those cases you will usually either get a perfect cube or something like that, or you'll get a simplification made obvious to you, although there are methods for solving cubics and higher using successive approximations (feel free to look them up if you think you might need them, but it's rare). Bear in mind, though, that most courses DO require you to be able to solve quadratics using the quadratic formula, so get used to it. practice practice practice :0) PS sorry about the ICE table... it didn't work out as planned. Anyone know how to insert a table?

well OK but last night I accidentally burned some parsley and wondered where the hell that weed smell was coming from

libavius, please dont try these reactions. it'd be a very dumb thing to do.

I can only really speak for the first year of a chemistry degree. group theory used to be required but not any more in my courses. differential equations might be slightly useful so that you'd recognise one when you're given one, but not really needed.

moved to a new thread (don't be lazy) in answer to your question, most of the math is fairly simple but it needs to be right, of course. You should be confident in your math skills. Off the top of my head we generally use (I teach first year): - algebra (linear, quadratic, and occasionally polynomial) - conversion factors - dimensional analysis (we use this a lot) - exponentials and logarithms base 10 and natural (log, ln, and e) - simultaneous equations - some very basic calculus