Any chemists here? I've got a question (with pictures!).

[Talono]

So I was messing around with some batteries the other day, and decided I would try to form some sodium or chlorine from table salt (sodium chloride). I made a rig from AA batteries and two paperclips to pass a current through melted salt, but I couldn't get the kosher salt I had hot enough (at least 800 degrees C) so I gave up on that.

I decided instead to dissolve the salt in some water and run the current inside the water, hoping that I could at least get some chlorine to gather on the anode. I did get some bubbles, but it was on the cathode instead:

If I let the battery in run for a long enough time, I'd get this weird blue-green flakes floating around in the water. Sometimes I would get orange stuff as well. Being the curious person that I am, I took a bottle of 70% isopropyl alcohol that was nearby and poured some of it in. Something cool happened: the alcohol was causing this repelling effect, making the blue-green flakes move around wildly whenever it came into contact with it. So in the middle, there was this little pool of clear alcohol with green flakes whizzing away from it. Eventually the alcohol just evaporated or mixed in with the water and the pool disappeared, but the flakes were still moving around.

So, anyone have any idea what this stuff is?

 

[Aught3]

If you're running an electric current through water you would expect oxygen and hydrogen to form at the anode and cathode respectively forming bubbles at both.

As for the green flakes I'd guess iron straight away but it could be a number of things.

What were the paper clips made of and do you have excess trace elements in your water supply?

 

[Talono]

I was only using one AA battery, so I don't think there would be enough energy to break a visible amount of water apart. In the absence of salt in the water, no bubbles would form. When salt was added, bubbles formed on the cathode. Sometimes the bubbles would go away shortly if not enough salt was put in, so I definitely think there's a reaction with Sodium/Chlorine going on.

I actually did this three times, the first with a bobby pin, and the other two with different types of paper clips. It came out the same in the end so I'm guessing they were made of iron/steel.

I used regular bottled water (not distilled) so I'm not sure if there's any excess trace elements.

 

[Spase]

Well... the easy way to know if you created any chlorine is if you had you would smell it. If you've ever been to a pool you know the smell of chlorine, it isn't particularly subtle.. and I'm pretty sure you aren't going to pull it out of solution running a current through a saline solution.

The bubbles should have been hydrogen and the reaction was electrolysis. Using only a small amount of current you'll probably only see the bubbles on the - terminal because that's where you get hydrogen which forms at a faster pace than the oxygen on the +.

The second effect you describe is less clear to me. I should mention that electrochemistry is by far my weakest chemistry... I met my ex right before that segment and stopped paying a lot of attention for a couple months...

So! The little green-blue flakes are probably a side reaction between something in the steel of the paperclip and possibly the chlorine. I'm not going to pretend this bit is much more than speculation. That said.. I have to wonder if the effect you saw with the isopropyl alcohol wasn't misinterpreted. Are you sure that the alcohol repelled the flakes or were they just pushed away from where you were pouring the alcohol in from regular fluid turbulence? My guess is it was the latter.. and if you want to find out you can repeat the experiment using pure water to pour into your solution as a control.

I'm suspicious of the idea that there was any repelling going on because I can't think of anything that would cause that. Isopropyl alcohol is miscible with water so there should never be a clearly defined line between the water and the alcohol and it's (the alcohol) not charged, and the flakes wouldn't have a net charge or they should be gathering at one of the battery terminals. I do think those flakes are super-thin and that very little turbulence is enough to carry them but that's about it. Oh! And even with heat 70% alcohol doesn't just evaporate.. at least not completely. You can leave the stuff out and while it will evaporate some, in a solution of mostly water (since you poured it into water) there's not reason to expect it would have all evaporated unless you're talking about many hours.

In summary, I think you saw electrolysis, and then the effect of pouring one liquid into another. I don't pretend to know precisely what your blue-green flakes were though.

Peace.

 

[Aught3]

I was only using one AA battery, so I don't think there would be enough energy to break a visible amount of water apart. In the absence of salt in the water, no bubbles would form. When salt was added, bubbles formed on the cathode. Sometimes the bubbles would go away shortly if not enough salt was put in, so I definitely think there's a reaction with Sodium/Chlorine going on.

Yeah the Na and Cl ions would help carry the current but you're right one AA battery isn't very much - I thought you had a few in series

 

[Talono]

[So! The little green-blue flakes are probably a side reaction between something in the steel of the paperclip and possibly the chlorine. I'm not going to pretend this bit is much more than speculation. That said.. I have to wonder if the effect you saw with the isopropyl alcohol wasn't misinterpreted. Are you sure that the alcohol repelled the flakes or were they just pushed away from where you were pouring the alcohol in from regular fluid turbulence? My guess is it was the latter.. and if you want to find out you can repeat the experiment using pure water to pour into your solution as a control.

The movement I observed was much more rapid and consistent than the turbulence caused by pouring. It was much more like the movement of fat/oil that you see when you put a drop of soap into water that has fat/oil floating on the surface, except it wouldn't stop moving (for a long time). Even after the isopropyl "island" eventually disappeared, I could see isolated areas of intense movement near where the island used to be.

Oh! And even with heat 70% alcohol doesn't just evaporate.. at least not completely. You can leave the stuff out and while it will evaporate some, in a solution of mostly water (since you poured it into water) there's not reason to expect it would have all evaporated unless you're talking about many hours.

True, true. I think the alcohol was just eventually overcome by the amount of water and just mixed in with it.



Perhaps I will do this again and get some footage this time.

 

[Spase]

I would be interested if you did it again with a control where you poured in water. I'm just having a very hard time imagining an effect that alcohol would have (like what you describe) that plain water wouldn't. The alcohol is already a solution with water (since it's 30% water). If you do tape it I'd be interested.. I can't say more without seeing it myself.

Peace.

 

[ExeFBM]

I'd have a look at your salt. A lot of table salts have many other compounds added in (may contain magnessium, silicon, aluminium etc.) and may be as little as 60% NaCl. Try and get a few different brands of salt, and seeing if the same thing happens. I'm also dubious about your isopropyl not mixing with the water. Could it have been something else in an isopropyl bottle?