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Tetrahedrite

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Everything posted by Tetrahedrite

  1. Where HA is a weak acid, pKa = pH +([A-]/[HA])
  2. Simple: get calculator, enter -log(1), answer = 0 A pH of ten would require a hydrogen ion concentration of 0.0000000001M
  3. A quote pertinant to the discussion at hand: "We have become, by the power of a glorious evolutionary accident called intelligence, the steward of life's continutity on earth. We did not ask for this role, but we cannot abjure it. We may not be suited to it, but here we are." Stephen Jay Gould (1941 - 2002)
  4. I thought exactly the same thing when I saw the pictures on the news! The amount of water dropping from that height also seems like it would further undermine the levies.
  5. The cyan blue colour you formed was an amorphous form of basic copper carbonate Cu2CO3(OH)2; this occassionally forms in nature and is called georgeite. Georgeite is, however, thermodynamically unstable with respect to the mineral malachite, and if left in solution all the georgeite will revert to malachite. Malachite has exactly the same formula, but is not amorphous (ie crystalline) and is green rather than blue. You may not of realised it but you just did a nice little experiment in something we call the Ostwald Step rule!!!!
  6. Imagine that...an ex-Democrat president being partisan when making comments about a Republican administration. *off-topic rant* I've really got to say something that has been bugging me for a while. PARTISAN is a Weasel Word! There seems to be a perception by certain learned fellow posters that if your views lean towards one political party or another, then it is a "partisan view" and therefore not legitimate. HOGWASH! An absolute obsession with "being in the middle" or "centrist" or "non-partisan" just serves to limit your ability to make reasonable judgements. Just because it is a policy of a political party, doesn't automatically make it wrong or bad. Those who sit "in the middle" of US politics would be considered horribly right wing in most other countries. I guess what I'm saying is that I detect a bias towards anyone who's opinions diverge from the percieved middle ground, and that the obsession with being non-partisan is sometimes misguided (and often annoying).
  7. I am not completely up on US political matters, but didn't the Federal Reserve chairman (Allan Greenspan?) come out and say explicitly that he "got it wrong" supporting the tax cuts for the rich, and that the policy had contributed to some of the current problems re the deficit?
  8. There really should be an IQ test for people posting on this site!
  9. Ok, if I was a lab teacher (which I am), I would be looking at four sources of error for each piece of wood. 1/ Error in height 2/ Error in length 3/ Error in width 4/ Error in mass I will go through an example to show how we would arrive at an absolute error. Eg for ease of calculation I will assume that the piece of wood is 10.00 x 10.00 x 10.00 cm and weighs 500.00g. Now errors in measuring lengths is usually given by half the smallest division on your ruler ie probably 0.05 cms, and, the error on a balance with two decimal places is usually 0.01 grams. So now what we do is work out the percentage error in each of the measurements. So % error in height = 0.05/10*100 = 0.5% % error in length = 0.05/10*100 = 0.5% % error in width = 0.05/10*100 = 0.5% % Error in mass = 0.01/500*100 = 0.002% _______ Therefore, total % uncertainty = 1.502% I assume you were calculating something such as density, which in this case would be 0.5000 g/cm^3. Thus the absolute uncertainty is 1.502% of 0.5000 = 0.00751 g/cm^3 Overall answer therefore is 0.5000 +/- 0.008 g/cm^3
  10. Not quite, glass is amorphous, having no regular repeating unit cell. Graphite, on the other hand, is in fact crystalline (it falls into the hexagonal xtal system from memory). What gives graphite the ability to conduct electricity is that it has layers of delocalised electrons in between the graphene sheets.
  11. All good points, IMO. Just to further pick up on the response, I heard on the news that the head of FEMA (can't remember his name) says he didn't even know about the people trapped in the superdome (now dubbed the terror dome) and the convention centre until nearly three days after the hurricane. Does anyone else think this is just ridiculous? I live in Australia and I knew before the hurrricane hit from news reports that people were going to be sheltering in these facilities. To say he didn't know about them seems very strange. This may be a media beat-up again, however. Picking up on what Pangloss was saying about aid being given to the USA, Australia has pledged $10 Million. The thing is nearly everybody I've talked to (this is a big talking point here) thinks that it is outrageous that we've pledged any money at all. I must admit that when I first heard about the money I was also suprised. The thinking is that if a similar thing happened here, the USA would not come to our aid at all, and that the richest country in the world does not need our help. Whether or not this is true, I don't know. On another note, the Australian Government and the Department of Foreign Affairs and Trade has been copping a huge amount of criticism about it's response to the Australian citizens trapped in NO. Australians coming out of the disaster zone have had a go at both the US authorities and the Australian Government for a perceived lack of action. This just illustrates that the political "fall out" may not be limited to the US.
  12. Over the last couple of days I have been watching the situation unfold on the Gulf Coast in the USA. It seems to be a very serious situation with potentially thousands of fatalities. The media is reporting (in Australia) that both the initial evacuation and the subsequent response were seriously inept. Some commentators here are suggesting that a third world country would have handled the situation better than it has been dealt with by both federal and state administrations (I do not necessarily agree). What is the US media reporting? Do you think the response was adequate? I have no first hand knowledge of the situation and I am wary of pre-judging those in charge with only second hand news reports. I think when things get back to normal, some serious questions will have to be asked, for example: -Is it resonable to "shoot to kill" looters who are stealing to survive? -Why was there no evacuation of those who could not evacuate themselves, the poor and the disabled? -Is there an element of racism in the response? -Was money diverted from a program to strengthen the levy to the "War on Terror (war on Iraq)"? -Was the National Guard's ability to respond hampered by a lack of personnel and resources due to the war on Iraq? When all's said and done, I think this situation is likely to seriously hurt those in charge, at all levels of government.
  13. If you mean CaCl2, then it is possible that some CO2 is evolved: CaCl2 + NaHCO3 --> CaCO3 + NaCl + H+ + Cl- (because CaCO3 is much more stable than Na or Ca bicarbonate) Then, because some protons are produced, they react with the carbonate to give CO2: 2H+ + CO3(2-) --> H2O + CO2 This is just an educated guess, I don't know the exact reaction mechanism.
  14. This should be in the religion section....... See also this thread relating to creationist posting here.........
  15. This is only true if the concentration of both the ammonia and the phosphoric acid are the same. At any rate the simple equation above is more correct than the equation given by qwerty which contains two acids on the same side of the equation
  16. I'm an extremist, apparently......
  17. Interesting research, does the US Navy have units specifically aimed at specific areas of R&D? Do you have to get security clearances to publish any of your work, no matter what the subject?
  18. Just a thought inspired by a thread asking how scientific journals work: Although there are many amatuer scientists who frequent this site, there are also quite a number of researchers, university graduates/postgraduates and professionals who are members here (myself included). These people may have a number of scientific publications, journal articles, research interests etc that are of interest to the various areas in the forum. I was thinking that if some of these people were to post some of their research articles (links) or simply tell others about what their research involves and why it is important, it may be a way of promoting real applied science to those amatuers as a university or career option. I know many of the members here are high school students, and I think that something like this would be a benefit to the members as well as promoting science forums as a credible arena for science discussion. What does everyone else think? Just a thought anyways........
  19. For strawmanning, Revprez has to take the cake.
  20. .......will the real conservatives please stand up, please stand up............
  21. My thoughts exactly........I just see this as trying to find hypocrisy where there is none. Just because 99% of the USA's foreign policy is based on Iraq, doesn't mean the rest of the thinking world needs to ignore the plight of those in Africa.
  22. Why exactly did you have the impression that people in the "lower left quadrant" (the overwhelming majority at this forum) would be any more favourable to sex offenders than people from the "oh so righteous" right? As one of the 76% of people who fall in that quadrant I find that comment quite condescending, and I believe some other people would as well. edit: just to clarify, I find that comment condescending because it implies that anybody who is left of centre (or Pangloss) is somehow morally inferior to those on the right, which is patently untrue.
  23. The term "kangaroo court" comes to mind when I hear how the commissions are being run....
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