exchemist

For non-cyclic alkanes the 2n + 2 rule applies. For single ring cycloalkanes is it 2n, because the joining together of the ends to make a ring takes the place of what would in a straight chain be 2 H atoms. For more complicated structures like the norbornane example, it is frankly not worth memorising a rule as they won't come up often. Just draw the structure and count them!

Propane is C3H8 (the 2N +2 rule). Propyl would be with one H missing, as it is a group joined to something else by one of the bonds to carbon, so C3H7- , unless the propyl group itself has further substituents. Yes, iso means it is branched with a methyl group on the 2nd carbon atom. Your example (b) seems to follow that OK as there is an isopropyl group (C3H7) on the 5th carbon atom of the octane backbone. Your example ( c ) likewise follows that rule OK, as there is an isopropyl group, this time written as CH(CH₃)₂, so again C3H7, on the 4th carbon atom of the decane backbone. In your example (d) the confusing factor is that the pentyl, C5H11, side chain on the 5th atom is written as a propyl group but with itself having 2 further methyl substituents. Each of these takes the place of what would otherwise be a hydrogen atom, so the propyl chain is now C3H5 instead of H7, with 2 methyl groups bolted on in place of the missing H atoms. Further note: There is a page on nomenclature here that may be helpful:https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Map%3A_Organic_Chemistry_(Smith)/04%3A_Alkanes/4.06%3A_Common_Names

Heh heh. I just hope it is useful and that you can understand my explanations.

The idea of horse dung, presumably.

It's a shame. I think the viola has a rather lovely sound, rather as a contralto often has a richer, sexier sound than a soprano. Bach's 6th Brandenburg for instance.

The Bunter sandstone would be a particularly fat stratum, presumably? 😁. Yaroo........

But this wing is being held rigidly at a certain angle to the medium. In your scenario that is not the case, surely?

Excuse me if I am being a bit dim here, but doesn’t CPT symmetry mean you invert all 3 parameters together? So your inversion would mean a positron, circulating in the opposite sense and going backwards in time, wouldn’t it? So it’s only gaining energy if time runs backwards. That seems sensible enough, surely?

What makes you think it should be gaining energy, when obviously (experimentally) it is losing energy. Surely it would only do that if time were to run backwards?

In your diagram, why does the ballast object not just hang down vertically beneath the vessel? At the moment I don’t see what would make it move forward.

Yes, I’m never convinced by arguments that a particular suboptimal solution should not be pursued, on the grounds that others are the same or lower cost. While I have some nervousness about CCS in particular, I think in principle that the world needs to pursue a large number of these countermeasures in parallel, especially if they are funded commercially rather than by government (i.e. by taxation). We simply can’t know yet which ones will be the commercial winners and therefore will get taken up at scale (cf. VHS v. Betamax). Also it may be that different solutions are viable in different circumstances, e.g. geography. On CCS specifically I am not a petroleum geologist so maybe I can be reassured by experts that it won’t leak.🙂 While you are right that oil companies will continue to drill if it remains profitable, I think we should all remember that that will remain the case while you and I still drive IC vehicles and heat our homes with gas. To be honest, I get a bit fed up when some people sanctimoniously blame oil companies and then sit back as if the problem is nothing to do with them, when it is all our lifestyles and legacy technology that continues to demand oil and gas. That is why it needs government action: we all have to change and that needs political input.

I think this is unduly cynical, at least where the European oil majors are concerned. (I realise that in US industry, naked, short term self interest is much more the norm.) Steady adaptation has happened as soon as government have taken steps to enable it. What you can't expect capitalism to do, in a free market economy, is to get companies voluntarily do things to make themselves uncompetitive. You need the whole playing field to be tilted towards the change you want to bring about, so that competitive advantage comes from changing. That is government's job. And the issue of interim solutions remains obviously important. Just as we can't phase out IC vehicles overnight, due to the investment society has made in them over a century, so we can't jump immediately to fossil fuel free power gen or home heating. The move to replace coal and oil by gas has been one interim move that my former employer has embraced with gusto, due to its strength in gas. That is self-interest sure but it is not evil or cynical, it is beneficial. The European oil companies have been trying for at least a couple of decades now to reposition themselves as energy companies, to ensure they still have a place in a zero carbon economy.. There is, as @sethoflagos points out, a huge investment in offshore wind by these energy companies. Here is a Shell one off the Netherlands: Where I agree with you is that with Trump on the scene, companies in the US are certainly scaling back their commitments to change. That goes for the motor industry just as much as the oil and gas business.

The arrow is a dative or coordinate bond.https://en.wikipedia.org/wiki/Coordinate_covalent_bond Resonance structures, which we have talked about before, show the contributing bonding arrangements. The real bonding is a blend of all of them. You can see that several of these show charge separation, whereby the electronegative oxygen atoms can withdraw electron density from the ring, leaving it with a partial +ve charge in the ortho and para positions. For this reason, the nitro group is said to be "electron withdrawing" and "meta directing" when it comes to the classic electrophilic reactions of the aromatic ring.

Well we do have Shitterton: https://en.wikipedia.org/wiki/Shitterton. This is a village in Dorset. It's not on a railway line though. Curiously, the name does actually derive from Old English scite, which has now evolved into shite (chiefly in the North I think) and shit, being allegedly due to a stream that was used as a privy, according to the Wiki article at least.

Jolly good. Until next time, then.😄

There is no paradox. But yeah, I'll leave you to dream up your next argument for why there must be a God. 😁

In that case, the causal chain would be infinitely long, but then there would also be an infinite length of time in which to allow it to evolve to reach the present. So one infinity would make up for the other one. This is the trouble with infinities. You get nowhere with these games. It's all rather silly.

No, coming from the past, obviously. For example, the reason you exist today is attributable, via a long chain of causality, to a series of events starting about 3bn years ago when the first systems of biochemical molecules began to make copies of themselves. And then, if you want, you can even consider the chain of causality that gave rise to that series of events, from earlier still, encompassing the formation of the solar system. There is no reason to see any limit to this. That is one of the preferred speculations: that time itself started just before the Big Bang. There was once a t=0, an origin, about 14bn years ago: https://en.wikipedia.org/wiki/Age_of_the_universe

This doesn’t seem to make much sense. I can’t see why an infinite past would violate causality. Surely so long as each cause precedes its effect one can have chain of causality as long as one likes? And then, even if infinite past did have problems, surely that would lead people to treat the big bang as a one-off, in order to avoid that issue.

No I didn’t visit those things but they do have an outpost of the Victoria and Albert museum, curiously. Big modern thing on the Tay waterfront, next to Discovery.

Here is a description in English: https://rope-source.co.uk/ropes/how-is-rope-made-a-comprehensive-guide/ This is by a British manufacturer, James Lever, near Manchester. A couple of years ago I visited the surprisingly interesting Jute Museum in Dundee, where among other things they had some of the machinery used to process jute fibres into ropes and other products made from jute yarn. This was the principal industry of Dundee in the c.19th.Apparently the jute industry there took over from processing flax from the Baltic into linen, Britain have used its early Industrial Revolution to become pre-eminent in mechanising the linen industry. Dundee was also at the time a centre of whaling in the Arctic and it turned out that whale oil was ideal for lubricating jute fibres, to enable them to be worked. So a happy synergy for the town. Incidentally, Dundee’s expertise in building ice-proof whalers (with a heavily reinforced wooden bow) was what led Scott to choose Dundee to build the ship Discovery for his first Antarctic expedition, which is now preserved there in dry dock. I had been led to believe Dundee was rather a dump, but in fact I passed a very informative day there.

True, though that was before we came along and started drilling holes in it……😉

Drax has been converted to burning wood pellets I understand, ostensibly making it close to carbon neutral. However there has been a prolonged campaign by Private Eye claiming these wood pellets are far from carbon neutral in reality. I'm guessing that this project could be partly to allay that criticism and partly as a pathfinder project. The steel industry in that part of the world must be a considerable emitter, I'd have thought, even if the blast furnace at Redcar has gone. And in any case, even if the wood pellet burning really is carbon neutral, the net carbon capture can be offset against other net emissions for the governments targets. I remain uneasy about burying CO2 underground. I just have this horrible feeling it will eventually find its way back to the surface. I have not come across any description of mineral chemistry to suggest it would be absorbed by the rocks.

I remember reading about these in the 1960s. As I recall, they seemed to be allowed mathematically, so long at they always travelled at speeds >c. However it looks as if their actual existence has subsequently been dismissed for a variety of reasons. So no, I do not think we are at a turning point for humanity due to speculations about tachyons. Though we may be for other more prosaic reasons, notably climate change.

I don't know much about QFT - and no doubt others will weigh in - but I had always thought the EM interaction between two electrons in QFT is mediated by virtual photons rather than real ones, and that a virtual photon is not a photon. There is what seemed to me, as a non-specialist, a fairly clear review of the distinction by Prof. Matt Strassler here: https://profmattstrassler.com/articles-and-posts/particle-physics-basics/virtual-particles-what-are-they/ I can't imagine there is anything in QFT that precludes a free (i.e. real) photon being emitted unless an absorber is identified. That seems nuts - what about the CMBR?