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John Cuthber

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Everything posted by John Cuthber

  1. Countries that haven't the self-control to avoid shooting down passenger aircraft should certainly not be allowed nuclear weapons. Oh!, hang on... https://en.wikipedia.org/wiki/Iran_Air_Flight_655
  2. Buy washing soda on-line. All of which cost money. Even if the only money they cost is the money you don't get by selling them- the so called "lost opportunity cost". Well, which is it? Have you done it (in which case you know it works) or not? Anyway, if you leave a solution of sodium hydroxide exposed to teh air, it reacts with CO2 and then dries out to give a crystalline carbonate (probably the monohydrate, though that depends on local conditions)
  3. If there was a cheaper way to do it, the commercial manufacturers would use that way. As it stands, sodium carbonate is already very cheap. You could, just to be different, separate chloride from sodium electrolytically- producing HCl and NaOH. And then you could react the NaOH with CO2 to give Na2CO3
  4. If you are lucky, you can "engineer out" the effects of expansion I always thought this was a really neat trick. https://en.wikipedia.org/wiki/Gridiron_pendulum
  5. I know it's just an illustration of the point but, it's worth mentioning that you should check that you are not trying to divide by zero, or you get stuck in an infinite loop.
  6. No, it changes to "-ous". Sulphurous, nitrous etc don't have an "i".
  7. For some things, zerodur isn't up to the job. This stuff is about 10 fold better https://en.wikipedia.org/wiki/Ultra_low_expansion_glass However, I'd not want to have to cut a screw thread into zerodur.
  8. About the same as gets released when you burn it. 141 MJ/kg 39 Kw hr
  9. 1. Yes, you can precipitate the silver in the excess solution as silver chloride by adding dilute hydrochloric acid (The acidity also prevents the explosion hazard associated with the ammonia/ silver complex). You can then heat the silver chloride with sodium carbonate or treat it with zinc and acid to convert it to sliver metal, then redissolve the metallic silver in nitric acid. 2. Just about. You can make copper (and platinum- but it isn't cheap) mirrors this way but most metals are too reactive. They can't be produced in water because they react with water. 3. Well, it's one of the commercial processes for making mirrors. The usual alternative is deposition of metal- typically aluminium- in a vacuum chamber. The set up costis higher, because you need a big vacuum chamber, but the running cost is low because you can use aluminum , and you don't have chemical waste problems. If you want to silver the inside of small glass objects then the chemical method is better. It used to be the standard way of making xmas decoration baubles.
  10. I realise it's probably impractical but, by far, the best way to reduce the contamination is to get the smokers to go outside. No matter how good the purifier is, there will be particles "en route" to it which you will be stuck with inhaling. To some degree, it's not a matter of how good the filter is, but how fast the fans can push air through that filter. For example, if the fans only move 10 m3 per hour but the room's natural ventilation is 100 m3 per hour, the filter isn't going to achieve as much as you would hope. https://en.wikipedia.org/wiki/Air_changes_per_hour
  11. I doubt that. Water is one of the best conductors. https://www.engineeringtoolbox.com/thermal-conductivity-liquids-d_1260.html However, the driving force of these thermometers is the expansion of the liquid. Ethanol expands much more than water does. (which makes it easier to get the thermometer to work.) In particular, near 4C the expansion of water is zero. It seems to me that it would be easier to use (more or less) pure alcohol. That way you don't need to carefully mix the right concentration every time you make a batch of thermometers.. In principle, you can use Raman spectroscopy to find out what's in the tube without opening it.
  12. Hard to say what he believes (honesty isn't his strong point). But he seems to think it's a credible idea. https://video.twimg.com/ext_tw_video/1212975913232715776/pu/vid/480x480/1MiELhLQD-ddfKu_.mp4?tag=10&fbclid=IwAR1Do_eqTfWa80RRlD1Gp09ToRiHUXV-tc3tyQ42jD58lBgHQwNU40ojB98
  13. About a hundred times as common as this. http://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=2240&context=chem_facwork
  14. Why? I can't think of any good reason for this. And vinegar doesn't "cause severe burns like acid" so...
  15. invar fused quartz I guess there are others too. In general, it's easier to thermostat the room.
  16. No. THF is a very weak base and resorcinol is a fairly weak acid. The resorcinol would dissolve, but there will be no reaction.
  17. No, the point raised consistently throughout that thread is that, while barking mad Republicans are ten a a penny, it seems relatively difficult to find their Democrat counterpart. You might remember this exchange of posts in that thread "Are you saying that this guy is not the best the republicans can come up with for this election?" "Well, the Dems have Biden, don't they?" "Ok, what has Biden said that was completely batshit crazy?" "Nothing as far as I know. I" I asked, repeatedly, in that thread for any evidence of any mainstream Lefty saying anything as profoundly dumb as the bloke who believes in dragons. That was in 2012. I am still waiting. So, I have a hypothesis. Only the political Right vote for people who are obviously clueless.
  18. I'm fifty-something man and , if I turn up in A&E with chest pains I expect to jump the queue in a way that my hypothetical twin sister wouldn't. I'm not saying that's good or right; I'm saying it's what happens.
  19. Oh, and while I remember, this... Not sure where that picture's from. Here's the link to the video which opened the thread.
  20. Did anyone actually read the judgement- or even the newspaper highlights of it? ""It is a core component of her belief that she will refer to a person by the sex she considered appropriate even if it violates their dignity and/or creates an intimidating, hostile, degrading, humiliating or offensive environment," he continued." Now that's not a decent way to behave. And Rowling was factually wrong to describe is as she did. Forstater was effectively sacked for bullying and harassment.
  21. At 400 bar, methane is still acting more or less like a gas. at roughly 40,000 bar, it won't be. There simply isn't enough space for the molecules.
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