Author Topic: High speed camera reveals why sodium explodes! (5 billion amps)  (Read 29031 times)

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Offline T3sl4co1l

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #50 on: February 01, 2015, 11:32:15 am »
That's what I'm saying, not only can you not simply "ground" it to the potential of the liquid (supposing that you can make a zero-potential connection -- in electrochemistry, this is generally accepted to be the "hydrogen electrode"), you can't even apply a voltage such that you can prevent or reverse it.  The potential is spontaneous and local, and so strong that it tears water apart, as well as the droplet itself.

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Offline c4757p

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #51 on: February 01, 2015, 11:46:38 am »
The reason is this: aluminum is so reactive that it is attacked by water, even when polarized with plenty of voltage.  It is impossible to apply sufficient polarization to prevent attack

But I was not suggesting stopping the reaction in the first place, so the experiment safe as it may be doesn't really prove much ... it's not reaction which causes the explosion, it's the surface of the metal repelling itself. If the aluminium is grounded can the surface of the aluminium still maintain a potential?

Grounding it to prevent potential is like grounding one side of a battery and hoping that the potential to the other side will disappear.

Even if you could, this happens fast enough that the inductance of the ground connection will make it practically an open.
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Offline IanB

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #52 on: February 01, 2015, 12:27:10 pm »
But I was not suggesting stopping the reaction in the first place, so the experiment safe as it may be doesn't really prove much ... it's not reaction which causes the explosion, it's the surface of the metal repelling itself. If the aluminium is grounded can the surface of the aluminium still maintain a potential?

But yes, it is a chemical reaction that causes the explosion. The chemical reaction is this one:

    2Na + 2H2O => 2Na+ + 2OH- + H2

The hydrogen gas produced has a much larger volume than the reactants, so it expands rapidly to make space for itself and in the process ejects water and molten sodium in all directions.

The speed at which this reaction can take place depends on the rate at which sodium atoms can come into contact with water molecules, which depends largely on the free surface area of the sodium. When the sodium is fragmented and pushed apart by the repulsive action of the positive charge accumulated by the initial reaction this causes a large surface area to come into contact with water very rapidly, which causes the continuing reaction to take place increasingly rapidly. A runaway reaction takes place which leads to an explosion.

This whole process is enabled by the molten state of the metal. If the metal was not molten it would not be able to spread out through the water in the way shown by the pictures. If the metal remained solid it would remain stuck together in a single lump.
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Offline T3sl4co1l

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #53 on: February 01, 2015, 11:29:55 pm »
I'd be interested to know how reaction rate (time from touching-the-surface-of-the-water to moment of "hedgehog instability") varies with initial temperature, and how the surface tension of the metal varies with temperature.

This will be complicated by the reaction rate being exponential with temperature (Arrhenius' law), but that should be factorable in the reaction rate.

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Offline justanothercanuck

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #54 on: February 02, 2015, 12:12:17 am »
You must watch his feminist videos to have an opinion about the videos enough to call them "dribble" and have the opinion that he "takes it too far".

Again, you're putting words in my mouth.  The truth is, that I've seen many YT gaming channels fall into this spiral of anti-feminism in an attempt to garner views.  Sad thing is, it actually works for some of them.

But overall, I'm rather disappointed in you Dave... I think I'm going to stop using your forum for a while.  Bye.
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Online helius

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #55 on: February 02, 2015, 12:44:03 am »
Again, you're putting words in my mouth.
LOL, when did that expression change its meaning to "direct quoted me"?
Have you ever heard of an ad hominem fallacy?
 

Offline dannyf

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #56 on: February 02, 2015, 02:28:25 am »
I liked it very much, particularly their willingness to challenge conventional wisdom / "settled science": yo cannot have more settled science than sodium exploding in water -> we all saw it with our own eyes and heard all the experts telling us those convincing theories of how / why it happened.

Those guys truly understand what science is all about and are the true scientists.

Bravo!
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Offline Dave Turner

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #57 on: February 02, 2015, 04:49:14 am »
Tim

Thanks for the URL about the existing batteries. It would be interesting to find out whether the new insight ends up having any bearing on their design.
 

Offline Marco

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #58 on: February 02, 2015, 04:59:17 am »
This whole process is enabled by the molten state of the metal. If the metal was not molten it would not be able to spread out through the water in the way shown by the pictures. If the metal remained solid it would remain stuck together in a single lump.

Maybe, depends if the reaction creates enough heat to melt solid Natrium before the explosion. Could be some type of cascade failure, still caused by the electrostatic force and a little luck to get the surface features necessary for the surface to start to blow itself apart in small chunks (eventually it will melt, just not sure if the surface melting is the actual trigger). Did they measure the surface temperature of solid Natrium when it explodes?
« Last Edit: February 02, 2015, 05:04:05 am by Marco »
 

Offline IanB

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #59 on: February 02, 2015, 05:12:50 am »
Maybe, depends if the reaction creates enough heat to melt solid Natrium. Could be some type of cascade failure, still caused by the electrostatic force and a little luck to get the surface features necessary for the surface to start to blow itself apart in small chunks. Did they measure the surface temperature of solid Natrium when it explodes?
But the sodium is molten when it explodes. By observing the progress of the reaction this is seen to be the case. When a lump of solid sodium is dropped into water it starts reacting and fizzing vigorously. Considerable heat is given off and the sodium very quickly melts and forms a ball on the surface of the liquid. The temperature is sufficient to ignite the hydrogen gas, far in excess of the melting point of sodium (about 98°C). Progress of the reaction in the various videos shows the following characteristic sequence of events: (1) fizzle; (2) molten ball; (3) flame; (4) explosion. See Periodic Videos, for example:

If we do a similar experiment with a metal having a higher melting point, for example dropping zinc or iron filings into hydrochloric acid we get vigorous effervescence and heat, but no explosion.
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Offline Yago

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #60 on: February 02, 2015, 06:26:34 am »
You must watch his feminist videos to have an opinion about the videos enough to call them "dribble" and have the opinion that he "takes it too far".

Again, you're putting words in my mouth.  The truth is, that I've seen many YT gaming channels fall into this spiral of anti-feminism in an attempt to garner views.  Sad thing is, it actually works for some of them.

But overall, I'm rather disappointed in you Dave... I think I'm going to stop using your forum for a while.  Bye.
The gamergate thing seem like another crock to me.
Basically a large percentage of gamers are young males, and if pulling pony tails was multiplied with rap and pop culture, this is such behaviour.
This gamergate just sounds like some hijacking by feminist nutters.
Why should protection of women's rights be the crux, why not attack all prejudice?

It seems the same here, to illustrate this point (in 1337 speak for the gamers too:P)...

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Offline Stonent

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #61 on: February 02, 2015, 09:02:39 am »
So this was done only with Sodium, imagine what Cesium, Rubidium or Francium might do?

Another just "what if" scenario, taking a chunk of sodium and firing a waterjet cutter at it.

Aside from what was already mentioned about trying to measure the current generated, I'd like to see this experiment take place inside a sealed pressure vessel, not so small that it would explode, but one where you could measure the pressure spike inside it.
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Offline T3sl4co1l

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #62 on: February 02, 2015, 09:58:12 am »
This whole process is enabled by the molten state of the metal. If the metal was not molten it would not be able to spread out through the water in the way shown by the pictures. If the metal remained solid it would remain stuck together in a single lump.

Maybe, depends if the reaction creates enough heat to melt solid Natrium before the explosion. Could be some type of cascade failure, still caused by the electrostatic force and a little luck to get the surface features necessary for the surface to start to blow itself apart in small chunks (eventually it will melt, just not sure if the surface melting is the actual trigger). Did they measure the surface temperature of solid Natrium when it explodes?

That's why I said

I'd be interested to know how reaction rate (time from touching-the-surface-of-the-water to moment of "hedgehog instability") varies with initial temperature, and how the surface tension of the metal varies with temperature.

Surface tension generally drops with increasing temperature, so the rising temperature as the reaction proceeds could be the threshold needed for this timebomb.

Specifically, there would be the balance between surface tension and electric surface compression, which as soon as the electric force wins out, splat, there it goes.

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Offline T3sl4co1l

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #63 on: February 02, 2015, 10:13:45 am »
So this was done only with Sodium, imagine what Cesium, Rubidium or Francium might do?

Another just "what if" scenario, taking a chunk of sodium and firing a waterjet cutter at it.

The other metals will have different parameters of surface tension, voltage (though not much more than the voltage of sodium), reaction rate and so on, so they may simply react spontaneously (probably with the same explosive mechanism), more or less.

As for the waterjet, the reaction rate will be significantly enhanced; it might simply blow away faster than it's able to explode (en masse) though!  The fragments will of course react quite rapidly once they go off on their own.

Quote
Aside from what was already mentioned about trying to measure the current generated, I'd like to see this experiment take place inside a sealed pressure vessel, not so small that it would explode, but one where you could measure the pressure spike inside it.

You could also use a pressure sensor to detect the leading edge (and rise time) of the shock wave.

Besides hydrogen, steam (and maybe some sodium metal vapor, too) should be part of the blast.

And yes, another thing to keep in mind: sodium metal has a relatively low boiling point, around orange heat.

Tim
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Offline EEVblog

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #64 on: February 02, 2015, 10:30:45 am »
You must watch his feminist videos to have an opinion about the videos enough to call them "dribble" and have the opinion that he "takes it too far".
Again, you're putting words in my mouth. 

I'm direct quoting you!
"90% of this guy's videos are anti-feminist drivel"
"I think he takes his videos a little too far."


Quote
The truth is, that I've seen many YT gaming channels fall into this spiral of anti-feminism in an attempt to garner views.  Sad thing is, it actually works for some of them.

Who talking about gamer channels? Thunderf00t's channel is nothing of the sort.
His channel is very much about calling out BS, be it in science, engineering, religion, or in recent times, the gamergate fiasco.

Again, I still note that you didn't refute my statement that his science and debunking videos are first class.

Quote
But overall, I'm rather disappointed in you Dave... I think I'm going to stop using your forum for a while.  Bye.

Because I like Thunderf00t's science (and athetist) videos?
Wow, someones a bit touchy. Bye.
 

Offline dannyf

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #65 on: February 02, 2015, 10:47:46 am »
Quote
"90% of this guy's videos are anti-feminist drivel"

Now you mentioned it: that thunderfoot guy is a little fixated, if his videos are of any indication.
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Offline IanB

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #66 on: February 02, 2015, 11:47:37 am »
That's why I said

I'd be interested to know how reaction rate (time from touching-the-surface-of-the-water to moment of "hedgehog instability") varies with initial temperature, and how the surface tension of the metal varies with temperature.
In Thunderf00t's video it is mentioned that this time is unpredictable, presumed due to surface contamination and surface oxidation.

In the successful experimental procedure they used a sodium/potassium alloy that is already liquid at room temperature, they cleaned it of all contamination, and they dropped it into the water through an inert argon atmosphere so the metal surface could not oxidize. With this experimental protocol the explosion happened predictably at the moment the drop of liquid metal hit the water. Once they had removed the sources of uncertainty there was no time delay involved.
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Offline mikeselectricstuff

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #67 on: February 02, 2015, 08:42:17 pm »
Something that might be interesting would be to use something like an inkjet head to fire tiny droplets of water, to get the expansion effect without there being enough water to complete the explosion
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Offline tom66

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #68 on: February 02, 2015, 08:58:55 pm »
I don't watch tf00ts feminist videos; they just don't really interest me.
 

Offline EEVblog

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #69 on: February 02, 2015, 10:37:20 pm »
I don't watch tf00ts feminist videos; they just don't really interest me.

That's the beauty of Youtube. You can like and subscribe to and even financially support a channel without liking all of their content.
Yet many people seem to be under the impression that content producers must make all their videos appeal to them  ::)
 

Offline Stonent

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #70 on: February 03, 2015, 12:24:04 am »
I've watched all of TF's videos on gamergate and well he picks it apart just about as well as Solar Freaking Roadways.
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Offline mswhin63

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #71 on: February 03, 2015, 01:53:40 am »
It is amazing after three years of research and peer reviewed paper on Nature that so many on this forum have debunked in less than a day of seeing the video.

Interesting video and from an electrical standpoint viable, although I wouldn't go into confirming or denying. I think some people didn't watch the beginning with interest as he already look the Hydrogen explosion and used it as his reference to the final analysis. The explosion was different to Hydrogen.

As far as emitting radio wave, entirely possible as I try to measure Molecular hydrogen natural resonance at 1.42GHz all molecules will vibrate and be detected. I haven't got the website handy, but there is a whole heap of measure frequencies for different chemical elements and compound that can be detected by radio wave. It would be just a need to locate the correct frequency. The magnitude of molecular hydrogen can be detected based on strength of its nuclear reaction. More experimentation is needed and as the guy said there is still a load of unknowns left to find.
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Offline electrolux

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #72 on: February 04, 2015, 11:12:41 pm »
I'm no scientist  ::) but in the vid he said that they were puzzled by the sodium exploding under water because there was no air. And the fire triangle (everybody knows it) , however did they take in to consideration the air-bubbles caused by the splash caused by dropping the sodium in to the water? :-\
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Offline T3sl4co1l

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #73 on: February 04, 2015, 11:35:32 pm »
There's 1000 times less stuff in a bubble of air than a droplet of water.  If it's exploding due to air... nah, it's just not. :)

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Offline Phaedrus

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Re: High speed camera reveals why sodium explodes! (5 billion amps)
« Reply #74 on: February 05, 2015, 04:28:26 am »
Well, it's a cool discovery and also how it came to be is a great story.

What i really don't like are the parts of the video, where he drones on how everybody else was wrong and didn't see the obvious.
Even going as far as cutting in some scenes of the periodic table guys.

That's just cheap in my opinion.
It's inherent to the process of scientific discovery that you look at an former overlooked aspect. It's also inherent to scientific progress to confirm, disprouf or add to older theories.

Periodic Videos actually made a video dismissing Mason's claims during the early stages of his research, and the clips shown are from that video and I believe an earlier one. So I consider it fair for him to take a shot at someone who dismissed him early on. I like Prof. Poliakoff, and Periodic Videos, but in this case they were quite publicly wrong.

I will say, I'm also tired of Thunderf00t's GamerGate videos. I do agree with him, broadly speaking, but I'm honestly bored of the subject, and Mason gets a little too vitriolic for my taste. But rather than get pissy about it, I just ignore those videos. I stay subscribed for his science content, which is generally first rate.
« Last Edit: February 05, 2015, 04:31:19 am by Phaedrus »
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