exchemist

35 minutes ago, StringJunky said:

I have to say that putting politically-charged subjects into class lessons that don't require them does annoy me. When one starts sliding such materials into coursework, it smacks of indoctrination. 

Yes I agree. However it is normal in most western countries for illustrations in children's books to show a mixture of sexes and ethnicities, simply to make sure all the children see the book, and the subject, as being "for them". Especially perhaps with maths, as this has some baggage of -ve stereotyping, viz. a history of being seen as "nerdy", or "for boys" and so forth.  So if that's all it is, then it's disgraceful that books are withdrawn for it.  

3 minutes ago, Intoscience said:

So what are you telling us that we don't already know? That light passes through space and is not reflected, so appears dark?  What a revelation!! 

He's banned.

2 hours ago, NTuft said:

to paraphrase @swansont, "time is the integral of frequency".

 f, units Hz, or s(econds)^-1, ergo, period T in units s¹

I think vibration is more fundamental than distance. What about distance as in wavelength?

I don't think I agree that time needs a motion -- it sounds like you're referencing speed. I think I agree with @md65536 that we can simply, arbitrarlly, define a period, and then we have a time period... though in some fashion this may entail an abstract clock.

Now, as for space, @Mitcher, do you suppose we can look at geometry à la mode de group theory, as non-circular defined? Could it not be said it is self-sufficient, that it is defined through mathematics, or do you suppose there is recursion there to circular definition?

The integral, with respect to t,  of 1/t is: ln t +C, surely?  

4 minutes ago, Externet said:

The wings pictures above do not have winglets for reducing vortexes.

A winglet is to reduce wasted energy from wingtip vortices. That is a different thing. 

No reply yet from the person I was hoping might respond, but someone else reckons they are vortex generators to improve the air flow towards the wing tip, where, due to the flexing of the wing, it is (so I'm being told) the part likely to stall first as the angle of attack increases. 

1 hour ago, paulsutton said:

Good point, i did comment on twitter that I hope fracking is a short term thing until we get alternatives up and running.   But yes we should put solar panels on a lot of buildings from the start,   and attach to older buildings too,   the new solar tech that has been developed not only seems to make panels more efficient but also more recyclable at end of life. .

Our government are here for short term action,   if we need engineers etc then we need to push engineering from year 7 (first  year of secondary at age 11)  so that we can develop the interest and also the skills for the future,  instead we keep kids at school till 18.

For many school isn't working, so why not let them leave at 14,  and work in engineering (in this case) as apprentices. By the time they are 18,  they will have skills, experience and qualifications that make them useful immediately,  compared to their peers who stay at school.

There are plenty of routes back in to academia later on n life too, 

Yes. The problem is fracking may be sold by our idiotic government as short term, but it isn't at all. The best short term options are renewables.

Regarding education, that's a different topic but I've just listened to an episode on "The Briefing Room" on Radio 4 about Britain's poor economic productivity, which (among other things) laments our rigid education system. This fails to turn out the sort of mid-skilled people one needs to provide the bulk of the workforce in a higher productivity economy, like that of Germany or France. Our record is very poor compared to theirs. We are fixated on A levels, which are extraordinarily narrow (my son chose the IB instead), and on going to university to study more narrow disciplines, often of questionable value. Different governments try different gimmicks, like the apprenticeship scheme, but there is no consistency and so it never takes root and starts to show results.   

6 minutes ago, paulsutton said:

So what about existing fields that have been closed down?, is the time taken to get them back up any shorter ?  I know some have apparently concreted over.

>5 years is a long time, 

I guess the government wants to be 'seen' doing something, only from this,  it seems like a sticking plaster over a gunshot wound.

If they want more energy, cheaply and fast, they ought to be erecting wind turbines and encouraging farmers to put solar panels in the fields instead of trying to ban the practice. That could make a difference within 18 months, if they can bypass the planning process for an energy emergency. But they are far right fuckwits, unfortunately. (Rees-Mogg as Energy Minister? Seriously?) 

My understanding is that some abandoned N Sea fields - which would be economic once more at today's stratospheric prices - could be restarted a lot faster than 5 years, but I don't have chapter and verse, I'm afraid.   

1 hour ago, paulsutton said:

The UK prime minister, Liz Truss has announced an end to the ban on Fracking in the UK.   I would be very interested in being able to separate fact from fiction on this topic.

I understand the basic principle which is to pump water in to underground reserves of natural gas in order to force these to the surface.    The explosives are needed to open up the rocks that hold the reserves of gas.

I goes without saying the usual social media channels will be full of all sorts of 'opinions' as to this causing earthquakes (which as far as I understand will be very low in magnitude anyway) and a host of other theories to help their objection argument.

Hence any links to actual papers or research and factual information would be helpful,  as I am hopefully going to be in schools as a Teaching assistant then being able to present some real facts would be great.   But this will be useful anyway.

Thanks

Paul

I don't think explosives are used, are they? My understanding is it is done via hydraulic pressure.  

An article in yesterday's Guardian, from a former geologist for Cuadrilla,  expressed the view that rocks in the UK are too heavily faulted for there to be many contiguous reserves, big enough to be economically recoverable. The current boss of Cuadrilla, interviewed today on R4, seemed more sanguine. However his estimate of recoverable reserves seemed to be 10x that of the British Geological Survey. I can't find numbers on this, unfortunately. But it seems there is no consensus on the size of the prize.

What I have found is papers on the BGS report on induced seismicity: https://www.gov.uk/government/publications/review-of-the-geological-science-of-shale-gas-fracturing

The other things to bear in mind, apart from induced seismicity, are the long lead time before gas from these new sources can enter the market (>5 years, typically) and the fact that when they do so, they will be priced at the global market price, so they will not make supplies any cheaper, though they can add to security of supply.  

2 minutes ago, KoelpinTad said:

I'm working on weight. I often have to convert ounces to grams or grams to pounds. Here's how I usually do it: write the numbers down on paper, find the formula, and then enter the numbers into the calculator. Everything seems complicated and takes my time, it makes my work slow and inefficient.

I am looking for a software or a website that allows me to convert easily and quickly.
Can anyone recommend it to me. Any suggestions are always helpful. Thanks everyone

I found this immediately on a web search: https://www.metric-conversions.org/weight-conversion.htm

There must be lots of them.  

1 minute ago, iNow said:

The clear issue here is the mistake you've made by calling Coors Light a "beer." It's better referred to as beer adjacent swill water. /BeerNerdShade

And I thought that was "Budweiser", the one made partly from rice. 

Real Budweiser, from Budweis,(Budweiser Budvar) is actually not bad, however. For a lager. 

11 hours ago, random_soldier1337 said:

Hi,

In my situation, I am dealing with two ideal gases traveling down a pipe at the same bulk velocities. I am only considering a 1-D treatment at the moment and I would like to find out at which point the two gases should be considered a well mixed, homogeneous mixture. Would anyone know either the particular formulation or even the subject matter to consult to determine the well-mixing of gases?

Thanks and regards.

You can also get "static mixers" to put in the pipe, to speed up the mixing and ensure it is complete: https://komax.com/the-gas-static-mixer-produce-high-quality-process-gases-for-many-application/

31 minutes ago, Externet said:

This is not a video, but the link to it shows - screen capture - Better image found :

 

I'm going to ask on another forum where there is an engineer who I think may have done some flying. 

4 minutes ago, Externet said:

Hi.

From memory, the belly red; the wingtip white strobe and the top red of fuselage beacons flashed sequentially; not simultaneous.  The questioned wingtop row of dots may be coincidental with one of them flashing.  The dots appeared like tiny 10mm diametre / 3mm high bumps when seen with the ambient light after aircraft stopped, but their diffused light was like 5cm diametre as seen on image.  There is a possibility of being reflective adhesive tape dots.  My vision is not superb, but was not a dream. 

I'm sure you are not dreaming! Since the beacon is often a rotating light, like a lighthouse beam, I imagine it would be expected to illuminate each one in sequence, though very rapidly. But we probably need comment from a pilot. 

1 hour ago, Externet said:

Thanks.  Nothing to do with leading/trailing edges nor extends.  On top of wings. Flashing during all clear night time trip. Seems Embraer RJ 145.  Commenting with a passenger on the right side window, we asked the flight attendant who guessed whatever to answer.

From the strong curiosity, found an almost decent image of the lights location, at daylight.  Center upper of image below.  Ahead of ailerons.  Unable to magnify.   The nearest is a group of three, then farther another nine, as in post 1 

L ooooooooo  ooo ==================================== ooo  ooooooooo R

 

Same details, in video, not flashing ---> https://www.youtube.com/watch?v=OfV9DnYPyo8&ab

 

Ah, I see. I wonder if it is significant that these are immediately ahead of the aileron. I think I've seen such things on other aircraft and always assumed they were not lights but small protuberances to aid airflow over the aileron. I could imagine that, if that is what they are, it's possible that at night they reflect light from a beacon on the fuselage. But I'm just speculating.  I don't know if we have a pilot on the forum who can comment. 

Did these things seem to flash in unison or independently?

5 hours ago, ferrocene2 said:

I was not in a position to analyse the product - I was a schoolboy trying out on the kitchen table something I'd read which intrigued me - and still does.

I am reporting what was written in Mellor's book and what I found. Of course I'm aware that chemistry has moved on and that there are countless compounds that have been produced that people hadn't even dreamed of. And, yes, he made mistakes - some of which I mentioned previously e.g. OsF₈ doesn't exist and PbF₄ does - and so do many other transitional metal fluorides which didn't receive a mention. Who'd have predicted in the 1930s the existence of xenon compounds including some of Xe(VIII)?)

What I am asking - and have yet to receive an answer to - is what was going on in Mellor's report and what was the bright green melt in the possible (and I emphasise the word possible) equation - and I cannot think of any iron compound which could behave in this way:

5KNO₃ + Fe₂0₃ + 4KOH = 5KNO₂ + 2K₂FeO₅ + 2H₂0

If you don't know - as appears to be the case - and/or aren't in the position to try the experiments described, just say so.

I well remember Cotton and Wilkinson although I no longer have a copy. Were they aware, I wonder, of Fe (-II) and Fe (0)?

 

By the way, didn't Geoffrey Wilkinson get his Nobel Prize for his work on organometallics, including ferrocene? If so, who better to know the unconventional (formal) oxidation states that can be involved?  

33 minutes ago, ferrocene2 said:

I was not in a position to analyse the product - I was a schoolboy trying out on the kitchen table something I'd read which intrigued me - and still does.

I am reporting what was written in Mellor's book and what I found. Of course I'm aware that chemistry has moved on and that there are countless compounds that have been produced that people hadn't even dreamed of. And, yes, he made mistakes - some of which I mentioned previously e.g. OsF₈ doesn't exist and PbF₄ does - and so do many other transitional metal fluorides which didn't receive a mention. Who'd have predicted in the 1930s the existence of xenon compounds including some of Xe(VIII)?)

What I am asking - and have yet to receive an answer to - is what was going on in Mellor's report and what was the bright green melt in the possible (and I emphasise the word possible) equation - and I cannot think of any iron compound which could behave in this way:

5KNO₃ + Fe₂0₃ + 4KOH = 5KNO₂ + 2K₂FeO₅ + 2H₂0

If you don't know - as appears to be the case - and/or aren't in the position to try the experiments described, just say so.

I well remember Cotton and Wilkinson although I no longer have a copy. Were they aware, I wonder, of Fe (-II) and Fe (0)?

 

OK fair enough then: I don't know. But I guarantee it was not an Fe VIII compound. 

Maybe @John Cuthber will have a comment. He seems to be the best on inorganic chemistry that we have on this forum. I was hoping this discussion might bring him out of the woodwork, but anyway this will now ping him whenever he next logs in.

9 hours ago, Externet said:

Hi.  

On a recent flight, perhaps on an Embraer aircraft, noticed diffused flashing red lights on top of wings that I never saw before.   Anyone knows ?  Took a video but does not show the detail, I was unable to ask the pilot at exit.

They are near the 'ends' of wings tops, a centered row of 12, aiming upwards ?  Seem as diffuse as if the wing was translucent and lit from the inside.  Just curious.

L wingtip   ooooooooo ooo ===================     Main fuselage    ===================  ooo  ooooooooo    wingtip R

Found a image on the web to better explain the location of those lights on top of wings.

 

Are you sure the aircraft was in clear air at the time? I've sometimes seen something similar when flying through very light cloud, which scatters light from the beacon lights on the underside so that a flashing glow becomes visible. Also could be something to do with the leading edge slat, or slot, that some aircraft extend for the approach and landing. I find it hard to think a diffuse beacon light would be helpful as a safety aid: you'd want something clear and bright, that could be seen for miles.

2 hours ago, ferrocene2 said:

Studiot: I joined many years ago using the name "ferrocene". I re-joined yesterday using the name "ferrocene2" as I couldn't log-on using my previous name. And, yes, I realise that Mellor died many years ago but I first came across his work in the late sixties at Manchester Public Library (the round building) where all volumes were freely available for reference. If he was completely wrong about iron (VIII) and the perferrates - which he may well have been - can anyone explain what may have been going on or account for my own observations which were not quite the same as he described?

I am no longer in a position to repeat the experiments outlined but other people must be.

(As for the compound ferrocene itself, I studied it at (BSc) degree level in 1971-72)

Did you have any evidence that you made an Fe compound with an oxidation state of VIII? Or was it just a mystery reaction product that was not analysed?

As far as Mellor is concerned, if he died in 1938 it seems likely that understanding of transition metal atoms and their chemistry when he was writing was less complete than today. The physics of QM only got going in the 1920s, after all, let alone its application to chemistry, and many of today's spectroscopic and other analytical techniques did not exist. 

I was at university about the same time as you and my Cotton & Wilkinson from that era says that for oxidation states of iron higher than III, "only for the states IV and VI are there substantiated reports of compounds." They go on to describe the tetrahedral, paramagnetic, ferrate ion.....  

23 minutes ago, dimreepr said:

Can you be more specific?

No.

37 minutes ago, dimreepr said:

A saying of my father was, "whoever I vote for, the government always win", which is of course true but in my societies version of pseudo-democracy it's because the balance of the government is becoming skewed, due to my vote being further diluted, by the latest winner with a minority percentage of the voting public. 

It's not a reason to stop voting, fighting or pointing it out; but it is a reason why I doubt my vote counts for much, especially since I'm poor (as a church mouse)...

 

OK, sure, all democracies are imperfect and some are worse than others.  But that's not the point I was addressing, which was your apparent objection to government going to war, or taking other decisions, without a referendum to consult the people. 

1 hour ago, Ned said:

I am clueless because personal opinion and comments seem to get a suspension or a ban . Are we meant to just ''preach'' present information ? Is there any point to a discussion if there is no neurological diversity , meaning alternative answers ? 

My started threads keeps getting closed down as soon as somebody doesn't like my opinions , so please tell me , what is the correct way to use a science based forum ? 

 

 

If you talk nonsensical crap, you must expect to get closed down. You have been banned over and over agin, from so many forums, that this message must have sunk in by now. The only explanation for you continuing as you do must be either that you have some  insane compulsion to talk crap or that you are doing it for fun, as a wind-up.  I incline to the latter view, as you know. 

1 hour ago, HWW said:

pictures say more than words : https://www.hwcv.org/empty-pagef738a1ef

please reset the headline to  Here you can see a Perpetual motion,    thank you

But on this forum you need to express yourself in words, unfortunately, or at any rate without sending us off-site to click on on links of unknown provenance. It's been ages since we had a perpetual motion machine, so if you an explain it without sending us off-site to a link, it would be fun to identify the flaw.

3 hours ago, ferrocene2 said:

Some years ago, I created a topic about the existence or otherwise of iron (VIII). What follows is an update after I was able to download as a pdf all but one volume of J. W. Mellor's "A Comprehensive Treatise on Inorganic and Theoretical Chemistry". In Volume XIII Fe (Part II) on page 936 it says:

O. Baudisch and P. Mayer 2 assumed that perferric acid, FeO₃(OH)₂, or H₂FeO₄ [it means H₂FeO₅], is produced when freshly precipitated ferrous hydroxide is oxidized by oxygen. D. K. Goralevich said that iron tetroxide, or perferric anhydride, FeO₄, or perferric acid, H₂FeO₅, is probably formed as a volatile, unstable compound when barium perferrate, BaFeO₅, is treated with an excess of dil. sulphuric acid, at a low temp. Perferric anhydride is insoluble in water, but soluble in dil. acids. He prepared bright green potassium perferrate, K₂Fe0₅.nH₂0, by fusing ferric oxide with potassium hydroxide and an excess of potassium nitrate, or, better, chlorate. The salt can be purified by sublimation; it decomposes very slowly "when kept in air; explosively, when warmed, on treatment with conc. sulphuric acid, or on impact if mixed with sulphur, phosphorus, or charcoal. It is quite stable in alkaline soln., but acids readily decompose it with evolution of oxygen and, in the case of hydrochloric acid, chlorine. Oxidizing agents like chlorine and hydrogen peroxide give a deep red soln. of potassium ferrate, with evolution of oxygen. Neutral soln. of the perferrate give no reaction for ferric ions until, on the addition of acid, decomposition has commenced. Similarly with sodium perferrate, the alkaline earth perferrates were obtained as white precipitates on adding a soln. of a salt of an alkaline earth to a soln. of potassium perferrate ; with barium salt, barium perferrate, BaFeO₅.7H₂O, is produced; and with a strontium salt, strontium perferrate, SrFe0₅.7H₂0. These salts are white and insoluble in water, alcohol, and ether.

This is all it says on Fe (VIII) despite devoting six pages to Fe (VI).

Questions:

1 Does Fe (VIII) exist? If it did, one might it to be less stable than Ru (VIII) and RuO₄ isn't very stable. Going across the period from Sc - Ni, Ti (IV) and V(V) are stable, Cr (VI) less stable than Cr (III), Mn (VII) less stable than Cr (VI), and Fe (VI) pretty unstable unless dry and stored in the absence of moisture and CO2.

2 Were all these observations wrong? As I wrote previously "I remember clearly that a dark green melt was produced, that it turned white when it cooled and solidified. [I also noted that water had no obvious effect] all contrary to what Mellor said. I cannot think of any iron compound which would behave in such a way under those conditions. There are a number of iron compounds which are white, but I can't think of any which would fit this particular bill". 

3 Mellor has numerous errors. For example, it describes the properties of OsF₈ which we know doesn't exists; the perbromates and PbF₄ didn't exist according to Mellor although we know they do.

4 Is anyone in a position to try these experiments? I performed them as a teenager in 1968 when I could easily get hold of the chemicals in question.

 

I'm afraid I am not au fait with what may have been tried recently in this area but I'd have thought there are reasons to expect Fe VIII not to exist, chiefly the effect of increasing nuclear charge as one goes across the period which will lower the energy of the valence shell orbitals, raising the ionisation energy and pulling them in, making them less available for covalent bonding as well. How recent is the work you cite that suggests Fe VIII ?

I imagine Ru VIII and Os VIII might be expected to be similar to one another (due the effect of the lanthanide contraction on Os), and both of them to form high oxidation states more readily than Fe, due to having more diffuse (less strongly bound) valence orbitals. 

But I can't claim any practical knowledge of this. Maybe someone else here can. 

1 hour ago, vv3rtigo said:

So the one with the Fluoro isn't stable?

No, you need to take a more nuanced approach to this. Nobody is saying the 3-4 alkene is "not stable". It's more subtle than that.

What we've been saying, and what the Zaitsev (or Saytzeff) Rule is saying [suggest you look it up], is that these elimination reactions, where there is more than one possible product, tend to favour the option with the more highly alkyl-substituted double bond.  You will in general get a mixture of products containing both options, but there will be a higher yield of the one with the methyl substituted double bond.

The reason is that alkyl groups are slightly electron-donating. You may be aware that alkyl groups are ortho/para directing in aromatic substitutions for instance. (F, by contrast, will be somewhat electron withdrawing.) More highly alkyl-substituted alkenes have greater stability (stronger bonds) than unsubstituted ones, as a result. How this occurs is a bit complicated, involving something called hyperconjugation, which gets into MO theory: you may or may not be covering this kind of thing in your course.  

But the question of "stability" is also worth thinking through a bit further, from the point of view of kinetics vs. thermodynamics. Both products are, so far as I can see,  thermodynamically stable, albeit the Me-substituted one is of somewhat lower energy - the more stable of the two. So that answers the direct question you asked. But which product is favoured in the course of a synthesis reaction can be a question of kinetics as well as thermodynamics. The explanation of the Zaitsev or Saytzeff rule given in my old synthesis textbook is that the electron-donating (hyperconjugation) character of the alkyl group stabilises the transition state, thus lowering the activation energy and causing that product to form faster than the other one. This may be something to argue out with your prof. 

On 9/18/2022 at 1:11 PM, dimreepr said:

It shouldn't, that's the point...

 

My chance of winning the lottery maybe equal to that of a king, but my chance of influencing him is roughly equivalent to my chance of shitting in his handbag...

Sounds like a good excuse to discount it...

Did the combatants in WW2 or Ukraine, decide for themselves to fight a war?

They elected the people who made such decisions.

That is how modern democracy works. We can't make the decisions of government: we have not the skill, knowledge or time to do it. So we choose, periodically, who to entrust these decisions to,  on our behalf, and then we periodically review their performance and decide whether to renew their mandate or give it to someone else. (This is pretty basic stuff, surely?)