sethoflagos

Looks very much like the parts are cut from a fair sized slab of 6mm thick elemental silicon. Thank you for bringing this to our notice. And sharing an imaginative application that certainly sparked my interest!

Metalloid rather than a metal per se. It's got a very high melting point so it won't object too much to having a hot pan placed on it. Pretty tough too.

Several reasons, but we can begin with entropy since you've overlooked a major consideration. The copper ions (actually Cu(H2O)6 2+) and sulphate ions have many more degrees of freedom floating around in the liquid phase than they do locked up in a solid crystalline phase - enough for that route to be thermodynamically favoured. Dissolving copper sulphate in water is an exothermic process anyway, due to the additional ligand bonds formed in the hydrated complex ion, so the Gibbs Free Energy arrow is only ever going to point in one direction (at normal ambient conditions at least). The extra bonding energy formed in such complex ions helps low reactivity elements (including platinum group metals) to leap up the reactivity index, so the latter is only a very approximate indicator, and often misleading if taken at face value.

It depends on your sign convention. For myself, work performed on the system by the environment is -ve, because that's how I was taught. And that's the convention adopted by your book. But if energy is added to a system, the energy of that system must increase, and that's the mental picture that it's important to hold on to.

The exercise is misleadingly worded. If a +ve amount of work is 'done on the system' then this must be understood as energy being added to the system whatever sign convention you are following, and therefore the internal energy change arising from that work must increase. This is where your method gave the wrong answer. The term 'expansion work' is commonly used as a synonym for any PdV process even when, as in your example, the system is being compressed. We know that the book intends compression because their PdV term is negative, and therefore dV is negative.

Raw coal-fired power station flue gas is hot. So to use it, you have to cool it down to a level that will not kill your vegetation. When you cool it to that degree much of the water content condenses out, dissolves the SOx and NOx combustion products, and produces a very acidic 'rain', which will likewise kill your vegetation. At least partial removal of the NOx and SOx is possible (I was involved in commissioning a few stages of the Flue-gas Desulphurisation Project at Drax Power Station in the 1990s) but it is a seriously expensive process.

If you're specifically interested in thermal storage where space is at a premium, then the quantity of interest may be the volumetric heat capacity (typically MJ/m^3/K) There's a table you can play around with at https://en.wikipedia.org/wiki/Table_of_specific_heat_capacities Fond memories of playing in front on my grandmother's Rayburn oven predispose me toward cast iron. However, water or high density masonry are probably more cost effective.

That's more like it. And for a soil type that's pretty much defined by its history of plant root and earthworm activity - ie processes that occur predominantly during the temperate growing season - might it be reasonable to say that the average temperature and precipitation pattern during the growing season are likely to be more significant than the winter temperatures? If you remove the skewing effect of North Dakota's very cold winters, I think you'll find that the growing season climate of San Antonio and Bismarck are not so very different.

Sounds reasonable for San Antonio, but your figure for Bismarck is very wrong. Last time I looked the Dakotas weren't tundra.

Not really true is it? Since almost all soils are the result of weathering processes (among others), and both the rate and nature of that weathering are temperature sensitive (freeze/thaw weathering is another obvious example) then arguably air temperature is a highly significant determining factor.

Many of these ideas are covered from a slightly different perspective here:

All practical machines when viewed from a global perspective produce nett heat. How do you propose to dispose of this reject heat (the heat you have removed from the water plus that due to inefficiencies) in such a way that you do not end up increasing the rate of global warming?

You've not presented any worth considering. Just fake news. And bad spelling.

Where did I say anything about ignoring such individuals? (That was your iinvention in your 22nd september post) No. Straw man #1: Falsely asserting I wished to ban religious books (21/9) Straw man #2: Falsely asserting I wished to exclude religious people from society (25/9) Straw man #3: Falsely asserting I wished to ignore religious (stupid, gullible etc.) folk (22/9) Contrary to your further false assertion, Roget does not believe these concepts to be synonymous. It is clear however that you are arguing in bad faith. So please desist from trolling me with your negative nonsense.

Where did I say anything about excluding such individuals from society? Straw man #2.

Empirical evidence does not require an explanation to establish its validity. However, you might consider why religious oligarchies bring with them a large package of strictures that are deemed exempt from public debate. Such as a creation myth for example that must be accepted as gospel in defiance of any observed evidence to the contrary. Or else. What benefit to society do such arbitrary faith based beliefs bring other than seek total subjugation of the individual? Absolutely toxic imho.

No need. You've presented no refutation or counterargument here, so I think I'll just stand my ground.

Because history.

Pretty much the same as any progessive political analysis I guess. Bad stuff happens under authoritarian regimes. Especially the religious ones where 'heresy' is a capital offence.

At first reading this appears to be just word soup. However... Did you consider the logical flow of this sentence before you wrote it? What on earth is 'an extreme version of democracy'? Surely, the principle of democracy is that everybody's vote counts equally irrespective of their position in society. How do you get more extreme than equality? Are you just trying to worm in the word 'extreme' to suggest that your view is reasonable and mine is not? That's hardly a noble tactic is it? More Daily Mailish that SFish. So what you appear to be stating is democracy = tyranny. Well, it's a viewpoint, but not one I'd share. If that's what you really believe then just have the courage to say it. We're all entitled to our opinions.

Much of the major North Sea Gasfield infrastructure was installed in the late seventies and designed for a 25 year lifespan. At a pinch, much will last a decade or so longer, but particularly in a marine environment, corrosion will eventually take its toll. So if a 30+ year old facility is decommissioned, there's no point in mothballing it for possible future reuse. It's far more economic to just make it safe and let it rot. In practice, reopening an abandoned field requires a pretty well total infrastructure rebuild.

Radial mixing of two fluids moving coaxially in a pipe is a function of the flow regime. In laminar flow, the dominant mechanism is molecular diffusion which ends up with a form of the heat equation to solve. in the turbulent regime, it's eddy diffusion, and that results in a Lagrangian function. The classic text covering this is 'Transport Phenomena' by Bird, Stewart and Lightfoot. Though https://en.wikipedia.org/wiki/Eddy_diffusion gives a reasonable introduction. In practical terms, chemical engineers generally default to allowing a conservative mixing length of 100 pipe diameters before presuming the two gases are well mixed. (Because the maths is a lot easier). If there isn't room for so much straight pipe, installing two 90 degree pipe elbows in different planes immediately downstream of the injection point has been used to justify dropping the mixing length to perhaps 30 or 40D. Alternatively, as @exchemist notes, there are a number of designs of inline mixing device that can be used.

🙂

As I said above, at my stage of life politics is no longer a big deal to me. Somebody else's problem. But thanks anyway for the sympathetic ear. It's appreciated.

Thanks very much for your insight, Ken. Your 'preferential voting system' is what we called 'single transferable vote' in my student days. I must admit that my small understanding of current Australian politics has come mainly from The Juice Media Youtube channel. I have no idea how 'fair' their viewpoint is but I find them infinitely more amusing than Rupert Murdoch's news output and they've lightened many a dull day. And to me they are evidence that the true spirit of anarchy is alive and well at least somewhere in the Melbourne suburbs.