John Cuthber

You can often get round this. I doubt that lemurs can fly, but I want to formulate a hypothesis that is positive (not least because proving a negative is "troublesome").

I therefore postulate that a thrown lemur will crash.

Sulphuric acid is a good electrolyte (if rather corrosive). The sulphate ion is very stable and the sulphur all stays in solution.

Also, as I answered earlier, washing soda works too.

With a good electrolyte like those and reasonable sized electrodes you should be able to see the bubbles of H2 and O2 with a 1.5V cell. A couple of cells should be plenty but, while it's less efficient, using more voltage won't do any harm.

Since you don't want AC and using the mains is dangerous anyway I wouldn't recommend it.

What does the "E" stand for in PEM?

Absurd as this sounds I think you need to add more water. Just enough to dissolve most of the solid at room temp. Then warm it up slightly to get the remaining solid into solution. Cool and add the seed crystal (that I forgot to mention earlier)- any speck of the solid. That should give you some crystals. If you let the stuff evaporate slowly you should net nice big crystals.

"I got this to work really well once with tap water a nine volt battery and some wire when I was a kid. For electrodes I basically opened up a couple batteries carefully enough not to break anything"

OK so you got a current to flow by using about 7 times the voltage that you need. My idea of " work really well" doesn't include something that inefficient.

Think about it, if you only need about 1.2V and you end up using 12V then you are throwing away 90% of the energy. Is adding an electrolyte that difficult?

Someone studying chemistry as the major part of their degree (ie a chemistry major) is not expected to be fully conversant with the subject- that's why they are still studying it so I don't see what Geneks is on about.

I think finding a deffinition of linear algebra and seeing how it applies to chemistry might be a good start. I had a look at wiki and it seems to give some good ideas.

Allmee, did you not understand my explanation that this does not, and can not, work?

If you go to university and study biochemistry then it's a safe bet that, while you are there, you will make the sorts of connections that could lead to a research career. Of course, you still need to be good at the subject and you still need to work hard.

Solutions of Rochell's salt are syrupy so you probably have the right stuff. Because these solutions are viscous the process of crystalisation can be rather slow (the molecules have to move through the solution to get to the right places to crystalise).

I'd try putting the stuff in the fridge overnight then, when it's cold, taking it and stirring vigorously (classically with a glass rod if you have one).

Trying to do this without an electrolyte will probably give rather disapointing results. While there are impurties in tap water that will make it a better conductor than pure water (which, btw, does conduct but rather badly) there are not many.

Bicarbonate of soda would work well but it isn't very soluble.

Turning it into the carbonate would improve the solubility.

Of course, you could just use washing soda too start with or you could heat the bicarbonate to decompose it.

If I didn't have any carbonate I would put a tablespoon full of bicarbonate in a teacup and add boiling water fairly slowly while stiring the stuff. The bicarbonate decomposes to carbonate and gives off CO2 (which is why ou add the water slowly).

The solution of carbonate (and some bicarbonate) will do as an electrolyte.

It would be interesting to compare this with just tap water using the same setup.

The remaining 0.27V or so will go into heating the stuff, but even if you get a few amps of current flowing ( which would be good going with a simple set up) you are only talking about a watt or so of power- nothing to worry about.

Pencil lead electodes work well enough. Welding carbons or the carbon rods from old zinc/ carbon cells work better. Of course, you can always ask father Christmas for some platinum.

No, there are roughly 100 strikes a second across the whole earth so it's an average power. It is sustained practically indefinitely. (Did you think lightning strikes lasted a whole second?)

If the used power is only half the installed power it hardly matters. Ther's still no point looking at lightning to solve the energy crisis.

(I should probably add that those figures are a few years out of date.)

I'm pretty sure that chlorine is a stronger oxidant than sulphur so that reaction is, if anything, less likely than H2S blackening PbCL2.

Burning octane isn't a reaction, it's lots, probably hundreds of reactions. Each of them IS reversible. Did you imagine that there was some sort of concerted attack by a dozen or so oxygen molecules?

Every step in the free radical chain reactions that occur in burning octane is reversible. Getting the whole sequence to run backwards is energetically possible but entropically disfavoured.

I think that the problem is that I don't understand some of the things there and I'm fluent in English. I think it's not a coincidence that they have marked with a §.

Those phrases are certainly not standard English.

For example, what does vegetal mean in

"Related Coursework : Vegetal Improvement and Genetics of the Populations "

I have some idea what

"§ Analyses and interpretations of gel on the chromatograph " means but I'm not sure, I think a biochemist or molecular biologist would be able to help.

Thigs like

"§ Castration of corn

§ Dating of female flowering " will get through a spell check without any problem - all the words are correct, but I doubt that they mean quite what was intended.

A typical bolt is (from wiki) about 500MJ. On average it hits about 100 times a second. That's quite a bit of power- 50 GW or so. The world uses about 3600 GW of electricity at the moment. (from this site http://www.cslforum.org/japan.htm)

Lightning isn't going to solve our problems. If it was easy to harvest then it could make some small contribution but it's a non starter really.

Pity.

"Van Halen belts"

http://en.wikipedia.org/wiki/Van_halen

'nuff said.

You can olny focus the laser down to a spot size of roughly half a micron.This is huge compared to the individual base pair (about a third of a nanometre). If you had an Xray laser then you could possibly do what you suggest but sequencing DNA isn't that difficult; it's a lot easier than getting an Xray laser. Even if you could get the xray laser you would still have problems. First Xrays destroy DNA. Secondly the signal from just one DNA molecule would be too small to see properly. You would need lots of molecules all lined up and I can't see that being easy. Even crystaline DNA isn't that well aligned.

IIRC telluric acid is a strong enough acid and oxidiser to dissolve gold so there is at least one acid that attacks gold.

The strongest acid you can get in any decent concentration in water is H3O+ (or, rather, its hydrated forms)

To get stronger acids you need different solvents. Flurosulphonic acid is already strong but adding a fluoride acceptor like SbF5 to it makes it even stronger.

http://en.wikipedia.org/wiki/Magic_acid

Just in case anyone isn't familliar with the term

http://en.wikipedia.org/wiki/Bitter_solenoid

Anyway, if you are using kilovolts to power magnets then I hope they are pulsed. That makes some of the problems more difficult (like building the power suuply and insulating the coil) but it means that the physical strength of the thing can be lower.

What is the application?

"What would be interesting is natural CO2 emissions were overlaid, so we could see exactly where all the CO2 was coming from and how it compared with man made emissions"

Well, the CO2 levels used to be constant at about 300 ppm, now they are rising.

It's fair to assume that the difference is due to mankind. If that's true then the net contribution from natural sources is nil.

Pointing out that the fraction of CO2 emisions from air transport is fairly small is one thing. Recognising that it is due to the actions of a relatively small number of people is another.

"Sorry, to sound naive, but why is CO2 a pollutant?"

Well, the obvious answer is to sit you in a room full of it; it's toxic.

Just because it's a natural product of metabolism doesn't stop it being a pollutant. People take considerable care to ensure that the sewers are kept separate from the water supply. When they fail, for example due to floooding, it's called pollution.

"Seems a strange pollutant that encourages beneficial growth"

Yes, at first it does seem strange; it's called eutrophication.

It's a problem because it upsets the balance of the system it enters. Nitrates and phosphates do it too.

It's a bit "old school" but that reaction works quite well. The other dominant product is sulphur vapour but I don't think that would blacken PbCl2.

I don't see why it's not the conditions I described; I passed H2S over moist PbCl2 and it went black.

In principle all reactions are reversible so while it's fair to say that the reaction would usually give lead chloride and a nasty smell it can be driven the other way.

I thought that the fact that the H2S could carry away the HCl would force the reaction to give PbS.

Anyway, I tried it and it did.

H2S from heated sulphur, parafin wax and sawdust in a test tube blackened a piece of paper smeared with wet PbCl2.

I wonder; if you got some nice white PbCl2 (I guess damp would work best)and passed H2S over it would it go brown?

Well, it should work but lead sulphide is so insoluble that the reaction might be a bit slow and, with dilute enough acid, it might not work at all or the reaction might even go backwards.

I think anyone who can honestly say this "I LOVE research and I LOVE being the first person to find out something new- knowing even before the PI... it's such a rush. " is probably a scientist, but I wonder, what's the definition?