exchemist

How horrible.

Cost is not the issue. It is the unwillingness of any supplier to sell lethal drugs for executions.

Strange. I would have expected CO2 to be far more uncomfortable than nitrogen, given that, at least as I understand it, the breathing reflex, i.e. a sense of suffocation, is driven by the concentration of CO2 in the blood rather than the level of oxygen. Have I got this wrong or are there other effects at play?

Haha, what a nutter! I’ve just tried a tiny pinch of salt in my tea. Can’t taste the salt and the tea certainly does not seem bitter, but then it doesn’t usually. Maybe it makes the 2nd half of the cup, when the tea has cooled below the optimum, a bit nicer. Interesting.

Yes I'll wear a pinstriped suit and bowler and carry a furled umbrella. No baseball cap and hideous golfing trousers for me!

The person behind this is apparently a serious tea drinker who puts milk in her tea a l'anglaise and says Britain is one of the few places where can reliably expect a decent cup of tea. So she's not some wacky Californian vagina-steaming nutcase, apparently. She says a very small amount of salt, not enough to make the tea perceptibly salty in taste, deactivates the taste buds that detect bitterness. What I don't quite follow is that if you put milk in your tea (a habit I think we got from India), that too cuts the bitterness from the tannins. So why do we need both? However I might try it this afternoon, just to see if I can detect a difference. What is funny about this story is the humorous, faux-panicky statement put out by the US embassy in London, averring that no way was the USA now trying to tell the Brits how to make tea!

Exactly. That’s what the potassium nitrate, aka saltpetre, does in gunpowder. KNO3, in which O stands for oxygen. Nitroglycerine is glyceryl trinitrate. - NO3 again. This is true of many explosives. The oxidiser is within the explosive, sometimes even within the same molecule, as with nitroglycerine. Ammonium nitrate fertiliser can also explode - there was such a disaster in Beirut, I think it was, a few years ago.

Do your homework.

Sure, analysing the composition of a particular material would be one of the focused activities I was talking about.

I must say the link strikes me as a rather silly article. Nobody goes searching for new compounds for the hell of it. There is a reason and the the search is directed and narrowly focused, according to the objective. The number of permutations is practically endless, given the number of combinations of elements and the fact that many compounds, e.g. a lot of minerals, don't even have a fixed composition. So the quoted figure of 1% strikes me as pretty daft and arbitrary - just a number some journalist has pulled out of his arse, basically.

Plenty of explosives have a built-in oxidiser, apart from gunpowder. The issue with all these things is how to ensure you get a suitably controlled reaction that is triggered at the right point of the engine cycle rather than going off at the wrong moment or too fast. You don't want an actual explosion inside an engine. Nor do you want an unstable compound that might go off outside the engine. For a lot of applications you would probably better off getting motive power, or heat, another way. The great energy source you have in space is the sun.

OK, however I am not clear now what the relative proportions of Na and K would have been in the Earth's crust , or crust + mantle, before the oceans formed. Without that information it seems hard to determine whether the reason for the difference in concentration of today's seawater is due mainly to the original composition of the rocks or to the differential leaching that we have been discussing. By the way, the poster who asked the original question does not seem to have returned. Perhaps he is watching and chuckling to himself as we struggle with it.😁

No I’m not saying that. Your previous statement was different and made no sense. Neither “a line” nor “an area” are “values” unless specified, which you did not do. And you can’t add a linear measurement to a measured area. Both of these things are obvious.

No.

I'm not sure I follow this. Surely both Na and K prefer granite to peridotite, the latter being ultramafic (Mg/Fe), don't they?

This is excellent stuff, which I feel sure must be on the right track. The next question, in my rusty chemical mind, is why this should be so. I suspect something to do with the size of the "cages" in the crystal lattice formed by silica tetrahedra, in complex silicate minerals. I feel sure the difference must be to do with the difference in size of the cations in some way. Generally speaking large cations are more stable in structures with a counterion network that has larger interstices for them to occupy. It may be that Na+ "rattles around" in these structures, has less stability and can slowly diffuse out as they weather. As I recall, these minerals have silica tetrahedra that can be joined either at vertices or along edges, giving different sized holes. If I have time later I'll see whether I can find anything further along these lines to explain cation preferences in these minerals.

The latter point is what I too suspect, to do with ion sizes. But I’m not a mineralogist. We need to check what these abundance numbers mean. Do they include the oceans or not?

Yeah but the point is why would rainfall deplete Na more than K by a factor of 30, given that there are similar amounts - within a factor of 2 or so - in the Earth's crust to start with, and both form equally soluble cations, more or less.

Aha, that makes a difference, certainly! But there is a factor of 30 to account for.

Well those numbers are certainly different from the ones I had found. But even so, if you look further down in the article, at the graph for abundance in the upper crust, which is where the minerals in the sea would be leached from, the difference seems to be considerably less. Here's another source also suggesting levels of the two in the crust are comparable: https://pressbooks.lib.vt.edu/introearthscience/chapter/3-minerals/. Ah. Maybe I'll have a look into that later - I need to go and cook a kedgeree for supper.

Interesting question. I see the abundance of K in the earth's crust is similar to that of Na: http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/elabund.html . Both are of course alkali metals with many soluble salts. I have a feeling it may be to do with the stability of complex minerals containing K, e.g. aluminosilicates. Perhaps the greater ionic radius of K+ forms more energetically favourable lattices , or it is harder for the larger ion to migrate within minerals and eventually be leached out by water. But I confess I am guessing. I would be interested to know the reason. Perhaps someone more knowledgeable can comment.

Yes that's the thing. A photovoltaic device induces a non-equilibrium population of electrons and holes in a semiconductor from excitation by absorption of photons, which creates an electrical potential and can do electrical work as the population is restored to equilibrium. At the moment I can't see how this antenna produces a non-equilibrium situation.

I've just caught up with this discussion and I agree about the apparent Maxwell's Demonish nature of the explanation on Wiki. The problem I have with it is just as you say, that the arriving photons are not in phase so there won't be any coordinated flow of electrons induced. All you will get is an increase in their thermal, i.e. uncoordinated) kinetic energy. The diode aspect of the device would seem to have to work at the level of individual photon-induced excitations. I am reminded of the "Brownian Ratchet": https://en.wikipedia.org/wiki/Brownian_ratchet But I would be most interested if someone can point out what I am missing.

That is being kind. This is Quantum Woo. Belongs in Religion rather than Physics, at best. Is Deepak Chopra involved? 🤪

We've been through the black hole thing. I pointed out there is no inconsistency in what Hawking said. But you've ignored it, being the aggressive and slightly mad idiot you clearly are. Enough of this tomfoolery.