zebediah49 t1_j68j9is wrote

> Pure water electrolyses if you try hard enough. It's just silly inefficient.

You have to be trying really really hard though. There's a classic demo where you can make water maintain a bridge between two beakers, by putting a decent few kV across it. You need to use extremely pure water to avoid electrolysis, which is pretty successful.

> > Table salt is normally not used by people doing electrolysis. Other salts such as sodium/potassium hydroxide, or if nothing better is at hand, sodium (bi)carbonate, are safer, similarly cheap, and also do the job better.

Well.. It's actually pretty common, but not for when people want to make hydrogen. The Chloralkali process (i.e. NaCl hydrolysis) is the primary industrial method for producing tens of millions of tons of chlorine and sodium hydroxide.


zebediah49 t1_j68ho0z wrote

> edit: just watched the vid, hillarious, they are just disolving the toxic metal particles in the water holy moly and use distilled non conductive water for the "proof". Yay humanity!

It might not be toxic.

Looked like steel, so you're primarily just producing iron oxide (rust) and dumping that into/onto the water. But also whatever else is alloyed into the steel. And I still wouldn't touch it.


zebediah49 t1_j5s0zx3 wrote

Reply to comment by Denamic in Why does hot air cool? by AspGuy25

The relevant point is that visible light will happily go through a normal glass window, whereas long-IR will not. Windows are opaque (and pretty reflective) to thermal cameras.


zebediah49 t1_j4ntrsm wrote

I happened to run into one of them a couple years back, and also happened to have a thermal camera on me at the time, and thought it was neat.

Temperature across a heat-powered fan on a wood stove. Note the nearly constant bottom section temperature, and a sharp 40F delta-T in the center where the thermoelectric pad is.

E: Sorry for the potato quality, but we're talking minimum budget FLIR Lepton here. And my MSX alignment is a bit off.


zebediah49 t1_j452jjo wrote

probably not. At 6' of neck length, they're looking at roughly 2.5psi worth of hydrostatic pressure to overcome. Probably another few feet from lungs being lower than neck.

It's not technically an impossible feat, but animal lungs are very generally not capable of that kind of vacuum pressure. Humans, for comparison, usually peak at around 1psi. The problem is that you're not creating that pressure with muscles -- it's from the bones in your ribcage being pre-sprung to expand; your muscles are just letting them do that. E: Right now there's another askscience thread on literally this exact topic. It's better than my sentence and a half..


zebediah49 t1_j2atw9y wrote

Can the twists and turns be the cop and PI missing or breaking something important due to being "distracted", and then totally screwing the case up by turning it into a coverup while they try to avoid getting in trouble?

The nominal mystery is solved in boring fashion half-way through because it was actually simple, and the actual plot is now whether or not those two are going to get caught and charged for their gross negligence?


zebediah49 t1_j1zrhqg wrote

They're saying that if the two are statistically indistinguishable, "there's no benefit to forcing staff to work long hours" is a 'better' way of phrasing it compared to "there's no benefit to not forcing staff to work long hours". The first implies that being good to your workers should be the default choice; the second the opposite.


zebediah49 t1_j1a0qqf wrote

Strictly speaking many external-heat systems don't. They use an absorption refrigeration cycle, and while the partial pressure of the refrigerant components changes around, the total pressure of the system is approximately constant.


zebediah49 t1_j18x0wm wrote

Note that this only works because of vapor pressure differences.

It is necessary that the compressor lower the pressure on the cold side such that its boiling point is below the cold reservoir temperature, and raise the pressure on the hot side such that that boiling point is above the hot reservoir temperature.


zebediah49 t1_ixlzunc wrote

Speed is also important. The slower you freeze something, the bigger the ice crystals, can get, and they wreck everything. It's why frozen pizza went from "trash" to "actually pretty okay" after the invention of flash freezing.

The smaller the object, the faster you can freeze it. As you try to freeze bigger things, at some point, because heat has to travel via conduction from inside to outside, you can't freeze your sample any faster.


zebediah49 t1_iw6ci53 wrote

> With the millions of tools in nature, it's only a matter of time for us to find and perfect the right one that can make this viable.

With the millions of tools in nature, our immune systems have acquired methods of defeating a frustratingly large fraction of them.