hermanntrude

buy a chemistry set. If you can't get to a store, order it online.

it's a general rule of thumb that when you combine the most reactive elements they form the most stable compounds. hence sodium (catches fire in water and sometimes explodes) and fluorine (burns the crap out of skin and reacts even with noble gases) forms sodium fluoride (boring white stuff). And cesium (explodes in air) and iodine (fairly reactive) forms cesium iodide (boring white stuff)

vibration might increase the speed at which transpiration can occur. Most of the process relies upon capillary action. Capillary action is slowed somewhat by the surface tension on the water, which often creates extra friction. If the capillary were shaken, though, it might help overcome the friction?

It seems i can imagine this fairly well but can't describe it too well. Perhaps someone else has the jargon needed

the molecule NH4OH does not exist in aqueous solution. It is entirely dissociated into NH4+ and OH-

It's kind of semantics really but in this case the ionic attraction is intermolecular rather than intra molecular since the two ions are both molecular but not part of the same molecule. However, it's traditional not to refer to ionic bonds as intermolecular, since they're actually a bond, even when in the temporary state we find in a solution of an ionic compound.

Hydrogen bonding is also in there along with london dispersive forces. Hydrogen bonding is of course the strongest by far. You could say that there are dipole-dipole interactions but in fact that's what the hydrogen bond is. it's just a REALLY strong dipole-dipole interaction.

nifty stuff.

well done.

Also, the RSC have a font, which is useful when word processing with chemistry.

link to RSC font

- I think it still is, although I'm not so sure now!

That would be the uncertainty principle

kind of depends on what OTHER ions you have in the solution. you dont have a solution of only Cl- ions do you? if it's H+ Cl-, you'll get a concentrated solution until the HCl starts evaporating. If it's NaCl you've got, you'll end up with a bunch of salt.

All depends on the counter ions

a more specific question:

Has anyone here ever added rubidium to water? Most chemistry instructors only go as far as potassium when demonstrating alkali metals with water. i want to try rubidium but want to stay safe. how much is safe to add at any one time? I know that it's not safe to store so i dont want to buy more than i can use at one time

much more in detail than you need, but there's a website with ALL of the regular polyhedra (not just the platonic ones):

http://www.mathconsult.ch/showroom/unipoly/index.html

which contains a clickable map:

http://www.mathconsult.ch/showroom/unipoly/list-graph.html

it sounds a bit like a musk rat, but i dont think we have them in the UK.

At first I didn't think an otter would be big enough to be mistaken for a cat; but I looked it up and the only otters found in Europe, the European Otter Lutra lutra, reach an adult height of 12 inches and a length of 2 -3 feet. You could probably mistake that for a cat.

 

 

They don't look that different from weasels, though, and if it looked nothing like a weasel then it may not have been an otter. The only other rodent-like animals that are that size that might be found in the UK that I can think of are raccoons, but it's hard to mistake a raccoon for something else. Other than that, all the bigger rodents aren't found in Europe.

weasels are MUCH smaller than stoats and otters and cats

if you want some sodium, just buy it. But be careful.

azides are pesky buggers and have a tendency to explode. At least with sodium you generally know when it will explode and why

I can recomend "Chemical Demonstrations: A handbook for teachers of Chemistry" v.1 and v.2 written by Bassam Z. Shakhashiri

 

ISBN 0-299-08890-1 (v.1)

ISBN 0-299-10130-4 (v.2)

 

A must for any Chemistry teacher

thanks. I'll see about getting it

true, good point. Unfortunately, that'd take about a year :0)

I'm grateful for your ideas so far. keep them coming and i'll eventually have a list of good'uns.

I remember the sulphuric and sugar demo from high school. I'll have to do that some time.

bump (is that forbidden here?)

hahaha good point TD

you should also include the oort cloud and the nearest galaxy. that way everything else just becomes a dot :0)

I think the universe can do what the hell it likes. It's bigger than me

When people get all stupid and loud-mouthed about Genetic modification, sometimes i like to let them get up a real good head of steam about it, and then point out that for about 15 years i was entirely dependant upon the secretions of genetically modified bacteria and i havent grown any weird protrusions or died of cancer or anything.

genetic modification isnt a frankenstein science. give it a chance

IMO it's probably worth hanging onto DVD for a while and waiting for the NEXT next level.

They're going to develop something bigger, and they're bound to want to make some extra cash meanwhile. If it's feasible, i'll wait till we have ulra-DVDs or whatever dumb name they come up with for them.

By the way my flash drive holds 2 Gb and doesnt get scratched to buggery every time i move it. It works nicely for me, since my computer is my only entertainment source (i dont own a TV and dont want to, since i download all my entertainment, commercial-free) and my computer is fairly old anyway.

yes i was considering luminol, although the courses are fairly basic. It might fit somewhere although i don't think they actually cover luminescence... it's fun anyway, but i am trying my best to demonstrations for reasons, rather than for fun.

Not come across glycerol/KMnO4 before... redox, i suppose? flames or just spitting and smoke?

I've heard of the jelly baby one before. I'll probably do that sometime but might have to be next year. I came into the position in the middle of term so some topics were already covered before i got my chance.

I'm also going to do an oscillating reaction but we didn't have any malonic acid in the stores so i've ordered some. and some fresh H2O2 to make a better elephant toothpaste... Perhaps if i can buy a small enough quantity i'll get some potassium for next year's alkali metal demo.

I am a new chemistry instructor at a college. I teach first year university transfer courses in chemistry and science.

I've been developing a list of demonstrations to provide throughout the year. So far i've got

• elephant toothpaste (decomposition of H2O2 in presence of a catalyst and some dish detergent)-- requires a laboratory because of the mess
  
• nitrogen triiodide-explosive decomposition. good demonstration of exothermic reaction and unstable compound. Also requires a laboratory since it gives off a large cloud of iodine and a bang loud enough to leave your ears ringing
  
• barium hydroxide octahydrate and ammonium thiocyanate. Two solids mixed together create a lot of water which dissolves the other products of the reaction. Entropy driven and very endothermic. Requires a laboratory due to toxicity of barium hydroxide and the smell of the thiocyanate
  
• ammonium dichromate combustion. Good fun but already included in the labs part of the course.
  
• cobalt chloride equilibrium with complex ion. Also included in lab section of the course. good demo of le chatelier principle
  

Can anyone list any more? they need to be fairly safe and demonstrate something that's covered at first year level.

I'd be particularly interested in anything that could be done in a lecture theatre safely.

sounds like an otter to me. where do you live? by a river or near the coast? wales, maybe, or scotland, somewhere rural? otters are on the increase, and although they're fairly reclusive this one may have just been going crazy, perhaps it had been hit by a car or was guarding young ones or something

Assume everything is false.

 

Chemkid

including chemkid's answer :0)

looks to me like three or so small peices of a crystalline mineral, stuck together by bits of fibre, possibly belly-button fluff mixed with sweat (or some similar combination of fibre and goo).

the lever-action you speak of is caused by the flexibility of the fibres which are glueing the crystalline parts together.

Seriously, go do something useful. Don't get obsessed by this object. Go out and get some bits of sand and other minerals and examine them under microscopes and you'll see that a lot of stuff looks really freaky at high magnification. Just because you never saw it before doesn't mean its weird.

coloured gases, nasty

coloured smoke... possible. I'm not sure what they use to make the smoke trails they use in stunt planes but i suspect it's just particulate matter scattered widely with some colourant in it. Probably wouldn't even need to be hot. Try talcum powder with some food colouring.