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hermanntrude

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Everything posted by hermanntrude

  1. the aufbau principle is a little less detailed than the n+l rule. The aufbau principle is usually only taught up to an including the 4p elements, since after that it gets a bit confusing. Also it's only taught that the 4s elements come before the 3d, but not why, whereas the n+l rule is a simple way of deciding which subshell to fill up next all the way through the periodic table. It still doesn't cover the exceptions like copper and chromium, though.
  2. the book introduces something I've never seen before, and it refers to it as being a hydrogen bond. That is, the bond between the triply-bonded acetylene and acetone. Now I could be prepared to believe that the Carbon in acetylene is more electronegative than most carbon atoms, but whether it counts as a hydrogen bond is another question... I guess that's a matter of semantics. Anyway thanks for showing me the exception to the rule. Note, though that even though the acetylene has a strong dipole on the C-H bond, even that book doesn't claim it has hydrogen bonds on its own. Therefore my original statement holds true, with one addendum: "no hydrocarbon on its own has hydrogen bonds"
  3. amit, water is [ce]H2O[/ce] NOT [ce]O2H[/ce]!
  4. the book isn't wrong. The book never said these things were hydrocarbons. You did that.
  5. these are all cheap materials. I might try this one day. After the end of the financial year :0)
  6. i'm still suspicious of both. But the throwing-into-the-air one has more chance of working, since the high surface area would increase the rate of evaporation which would reduce the temperature massively, and of course the high surface area would also cool it quickly too.
  7. winter tyres with little studs in them helps a lot. Also most cars are large four-wheel drive beasties. Also snowploughs. Salt and grit isn't very helpful in deep snow.
  8. I'm english originally, but been living in canada for 2 years and newfoundland for 1 year. Not sure what that makes me... But canada isnt the only place to do half-hour time zones and as i said before, some places even do 20 minutes
  9. ha yes I know. I was laughing the whole time. we're due to get 5-10cm of snow tonight and then another 15-20 on saturday followed by a few more on sunday. Life will continue as if nothing had happened. I probably won't even get a day off work tomorrow :0( One day last year in a nearby town (on an island) had 63cm of snow and winds of 147km/h in a single night.
  10. it's newfoundland, which is part of canada. I've experienced -40°C (without the windchill) before when I lived in northern alberta. I never tried throwing boiling water into the air... it might have worked but I am suspicious of claims about that. And i'm certain that pouring it straight from the kettle wouldn't work. You'd need to throw it into the air to give it a bigger surface area.
  11. yes the common example of carbon participating in hydrogen bonding is when Chloroform and acetone are mixed. A hydrogen bond is formed between the C=O bond and the C-H bond. This happens due to the inductive effect of the three highly electronegative Cl atoms. However, neither of these compounds is a hydrocarbon. As to whether carbon has any electronegativity, it depends how you define it. Personally i think of anything with a Pauling electronegativity of 2 or lower as being electropositive. In a hydrocarbon, the dipole is miniscule, and almost negligible. You are correct in saying carbon has some electronegativity, but you are labouring a useless point since it's such a small electronegativity difference when compared to hydrogen, that essentially no dipole exists, and certainly nothing remotely close to a hydrogen bond.
  12. neither of those is true. Time zones are not all one hour different from each other. Canada uses mostly time zones which ARE one hour different. PST, MST, CST, EST and AST are all one hour apart, but NST is a half hour different to AST, and 3:30 different to UST. As for St John, I'm assuming you mean either Saint John in new brunswick, which is on AST, or St John's in newfoundland, which is on NST.
  13. I tell my students "google is your friend" ALL the time. I'm not sure if I picked it up here or introduced it, but i've always believed it. I also tell them (politely) to stop being so stupid about wikipedia. If there's no good reason for someone to falsify information, it's trustworthy, and even if there is a good reason there are people checking it all the time.
  14. hermanntrude

    brrrrr

    it's been stupid-cold here the last few days. yesterday the windchill temperature was -27°C (246K). today it's a balmy -16°C! the snow is so deep that they're picking it up with backhoes, filling up trucks and dumping it outside town to prepare for the next snowfall.
  15. manking? i'm sorry i don't understand your question.
  16. you'll need a salt of the precious metal too.
  17. the last part of your answer is wrong. You are assuming that every time zone is exactly one hour different from the next. that is simply not true. Newfoundland is 3:30 behind GMT, whereas labrador is 4:00 behind. There are some areas in the world where time zones differ have 15 minute or 30 minute differences. here is a good time zone map
  18. is diethyl phthalate your solvent for the vials above?
  19. hydrogen bonding does not exist in hydrocarbons. Your book was wrong, or you misinterpreted it. Hydrogen bonding only occurs in molecules with a bond between a hydrogen atom and a very electronegative atom such as F, O or N, and sometimes Cl. Carbon isn't electronegative at all and so any molecules containing only hydrogen and carbon cannot contain hydrogen bonding.
  20. which is why you put it in a dessicator
  21. orbital viewer chemputer simchemistry
  22. please read the posts in a thread before supplying your own information. it avoids repetition.
  23. hydrogen bonding does not exist AT ALL in hydrocarbons.
  24. do you have details for the synthesis of TCPO? I can make TCP or buy it and i have oxalic acid... would those be good starting materials?
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