woelen

Yes, I've checked that out, while reading your post with the fairly long quote. I largely agree with this page and the sceptics, which are expressed in that. But still, I think independent research on this subject will be useful. So, although I have serious doubts on this, I do not dismiss it completely as rubbish. I wait until independent research is done on this and then I decide, whether it is rubbish or something really new and great.

Aluminium foil makes a gas with strong alkalies, like sodium hydroxide. With ammonia, the rate of formation is so low, that it is not of any practical use. Maybe, if you leave the foil in ammonia, and you look at it the other day, then you could see small bubbles of hydrogen gas, but the reaction will be very slow. You also can make hydrogen gas from aluminium and dilute hydrochloric acid. Be careful with this reaction though. At first, it proceeds slowly and smoothly, but it tends to go faster and faster and also becomes very hot.

What kind of experiments are you thinking about, when you have HNO3? Maybe we can help you with easier to obtain alternatives.

The I/V curve actually is very similar for these solutes. The model, which I derived on that page is valid for any ionic solute, the only difference being the parameters. The forward voltage drop and the redox potential can be somewhat different. For the solutes H2SO4 and Na2SO4 you can take a redox potential of appr. 2 V and a forward voltage drop of 500 mV to 1 V. As YT pointed out, you need only volts for electrolysis, not hundreds of volts or kilovolts. Use high current and low voltage, but keep in mind that the current density at your electrodes does not exceed 100 mA/cm². With an oxygen producing cell, it would even be better to keep the current density as low as 50 mA/cm². So, you need large electrodes. Of course, if you have a high current high voltage supply, then you can put cells in series, but collecting the gas from all different cells separately will be quite difficult and require a lot of apparatus. Never mix O2 and H2 in more than ml quantities. That definitely will lead to heavy explosions and accidents.

Ha, I see that you have quite a lot of knowledge of electronics. Then I would say, build yourself a current source of 1 A (this can be done with an LM317) and use that for the electrolysis. You definitely do not want to use AC, as that is extremely dangerous and using wall outlet voltages (115/230) is straightout idiot. If you want things really simple, then use a 5 V power supply and a fairly concentrated solution of Na2SO4 or dilute H2SO4. Another cheap but much better way of doing electrolysis is using an approximate current source. I have made this from a 12V power supply (old PC PSU) and a series resistance. See http://woelen.scheikunde.net/science/chem/misc/psu.html This page you should definitely understand. I've written this with people in mind, who absolutely have no knowledge of electronics, and only have knowledge of chemistry. You need to store the H2 and O2. Even with 2 A you'll net get sufficient H2 / O2 at once. Maybe you could use a higher voltage source and put cells in a series circuit and adjust the current to 1 ... 2 A through all different cells. The cell voltage is somewhere from 4 ... 6 volts at normal operation. I've investigated that as well. Maybe this characteristic can help you determine the type of power supply you need. http://woelen.scheikunde.net/science/chem/exps/electrolysis/index.html

Hamseen, forget about nitric acid in OTC products. You'll either have to go to a special chemical supplier, or you have to make it yourself from H2SO4 and KNO3 or NaNO3.

Have a look at http://www.emovendo.net. This supplier has a lot of N45 magnets (or even N50) for fair prices. I purchased many things from them and they are very helpful and really quick in shipping things (unfortunately I only could buy chems/elements from them, they don't ship the ultrastrong magnets overseas, for reasons I can understand).

All of the latter posters: read the article. It explains what happens, so there is no need for speculation at all. Whether that explanation in the article is true or not, is yet to be determined, but there is an explanation. I mentioned this whole stuff on a Dutch chemistry forum, and a few students are going to do the experiments and see if they can reproduce it. They can use this research as their final research for passing their studies. So, they have the time and the resources to repeat things. Let's wait what will be the outcome.

Here is a little AVI movie of the xenon arc. Unfortunately it still is 7 MByte and it also is quite noisy (while the original isn't). On compression it becomes really noisy and that is a pity. But the movie shows the effect sufficiently well. http://www.oelen.net/pics/xenon-arc.avi Please, first download the file to your PC and then play it locally. On my PC the file is not played correcly directly off the site. I do not know why. When it is put on a local disk, then it plays OK.

YT, I'll use your rule as thumb. Rocket Man's idea also sounds very nice. I have some fuses and I'll open up one of these. In that way I have the needle-like structure and I have a rigid mount for the spark gap. Right now, I'm hassling around with wires, which constantly move and which make it hard to experiment. If I have some sparks in air, which can be sustained, then definitely I'll make pictures of that and show them over here. I also made a real 240 V-AC / 350V-DC power supply, capable of delivering 200 mA at the AC output and 150 mA at the DC output. This power supply allows me to do less dangerous experimenting. I use a center-tapped 1 : 1 transformer. In this way, I have all voltage floating and touching a single wire does not lead to electric shock anymore. Before this, I did all experiments directly from the wall-outlet, with just a 250 mA fuse in between. Now, things are safer .

The breakdown field strength of air is around 3 kV/mm, so that explains why I did not get any sparks. I expected the breakdown field strength to be much lower than this. I've done experiments with much smaller gaps and a series resistor of 1 M and a series connection of capacitors of 22 nF/1000V. With this, I can make nice small sparks, but I did not yet have sustained arcs in air. That of course requires much lower than 1 M resistor values, but I do not want vaporized resistors or other components. The flash tube, shown in the pictures above, contains xenon gas. Apparently, with xenon gas (at low pressure???) the breakdown field strength is much lower. The total length along the tube is appr. 40 mm, so I estimate the breakdown field strength to be only 80 V/mm or something like that inside the tube. Why is it so low inside the tube and do I need 3 kV/mm in air? My circuit is capable of triggering a miniature flash tube from a small camera. Apply a voltage of 300 V on the main leads of the tube and connect the trigger to the capacitor string, then a flash is produced and the 300V capacitor is discharged as well. This of course also an be done with a trigger transformer and a TIC106D, but being able to do without this, shows that the voltage must be at least a few kV. Unfortunately I have no means of actually measuring such high voltages.

Officially it is not called aqua regia, but it still works quite well as such. The ratio is not critical at all.

I have experimental results and these tell me that iodate only is a pale shadow of the other halates/perhalates when looking at its reactivity. The results I posted in a separate thread: http://www.scienceforums.net/forums/showthread.php?t=21131

NaHSO4 definitely does not give off SO2. It gives off water at a few hundreds of degrees Centigrade: 2NaHSO4 --> Na2S2O7 + H2O At much higher temperature (I think around 1000 C) it decomposes to give Na2SO4 and SO3. The V2O5 catalyst method indeed can be used (and is used in industry) for oxidizing SO2 to SO3, but that it very difficult in a home setup. You need specially prepared V2O5 in a long and very hot tube (IIRC around 400C) and then the O2 from the air reacts with SO2 to form SO3. Not something one easily does at home.

I discovered that the device also supports a kind of "arc" in a xenon flash tube. Normally these things require a large capacitor (e.g. 300 uF / 350 V) and a trigger voltage of a few kV to get an arc. With such a trigger voltage and a capacitor, charged to 350V or so, the arc only is maintained for milliseconds at most. I, however, could maintain a low current arc with a series resistor of around 1 MΩ. The result is really impressive. The arc is flashing around in the tube, it sometimes narrows and becomes sharp, sometimes it becomes more fuzzy. I made some pictures of it. The two pictures below are low-exposure pictures, showing more details of the arc. In reality, the background had normal light conditions. The first picture was made, while the arc was fuzzy, the second while it was sharper. The tube becomes quite hot. After disconnecting the power supply, I felt the tube and it was so hot, that I could not bear it on my skin. I also made a little movie of this. I'll see how I can compress that somewhat. Right now it's over 40 MByte, which is too much for my website. But I already want to show these nice "arcs".

I've made a 3.5kV/100 μF Villard cascade array, which stores, when fully charged appr. 60 J of energy (Ceff = 10 μF). I, however, could not make a spark with this with a distance of a few mm . I used a series resistor of 100 kΩ and hoped to make a spark with this, which then could be sustained for a while. Nothing happens at all, not even when I have a few mm between the end-points. I dare not handle any of the wires, while the thing is charged. I also dare not make a spark without the 100 kΩ resistor. I once had an accidental discharge of 3 caps in series and that was quite a nasty bang already. Any idea what I should do to get a decent spark with this, which can be sustained for a while? The device is great, however, for lighting large neon tubes. I also have a strange old glass tube (size appr. 2 cm), which when connected to the Villard cascade in series with a resistor gives a weak purple light. I think that most of the light of this tube is UV. A series resistor of 100 kΩ becomes quite hot, when connected to the tube. So, I'm quite sure that the cascade is working properly.

The best aqua regia is made from a 3 : 1 molar ratio of HCl to HNO3. This is because the intended reaction is as follows: 3HCl + HNO3 --> NOCl + 2H2O + Cl2 If excess HNO3 or excess HCl is used, then that excess simply remains in solution and less than optimal amounts of Cl2 and NOCl are formed. But in practice, the making of aqua regia is not critical at all and anything from a 4 : 1 to 2 : 1 ratio works OK.

I can add to the questions of Rocket Man that hydrogen indeed can have a negative charge on it. Such an ion, written as H(-), is called hydride. Hydrides can be purchased commercially, albeit not by the general public in most countries. Some examples of ionic hydrides are NaH, CaH2. These are very reactive compounds, which react with water, giving hydrogen gas and hydroxide ion, OH(-): H(-) + H2O --> H2 + OH(-)

YT, nice post . My oldest daughter is 10 years now and I've done quite some nice experiments with her already. She may play around with NaHCO3 and some weak acids freely, nice for bubbles and fountains. Under my supervision she also did quite some nice precipitation and color reactions (e.g. pH indicator color changes and metal salt complex formation). I do not yet explain all the things, only the very basic concepts, like that when atoms rearrange, that the properties can change completely. I even showed her some of the red P/ KIO4 experiments, and the Mn2O7/H2SO4 experiments, but of course only as a demo . Kids really like this kind of things. They are surprised by the color changes, effects, smokes etc. Now it is time to raise interest, the explanations will follow later.

Silkworm is right, cathode and anode are not the ions, but the electrodes. The names are indeed somewhat confusing. Formulating it in the way, as given below, may help you remember the correct terms. Cathode --> Negative pole, and cations go to the cathode, they are positively charged and go to the negative pole. Anode --> Positive pole, and anions go to the anode, they are negatively charged and go to the positive pole.

Borek, that is a great read. I've also seen it on sciencemadness.org already. It is a pleasure to see that there still are magazines, who write something else than the fear and terror crap, which we usually can read about (home-)chemistry in papers and on websites.

What you are saying is only true for some transition metals. There are some carbonates of transition metals, e.g. FeCO3, Ag2CO3. Most transition metals, however form so-called basic carbonates, such as Cu(OH)2.CuCO3, Ni(OH)2.NiCO3. These are mixed hydroxides/carbonates. Only a few do not form carbonates at all, e.g. Cr(III) and Fe(III). This all has to do with the acid properties of the cations. The higher the oxidation state of a metal, the more acidic its ion is. E.g. CrO is purely basic, Cr2O3 is amphoteric (can exhibit some acidic properties as well), and CrO3 is purely acidic and forms H2CrO4 (and H2Cr2O7) in water. Cations, which exhibit acidic properties, hence cannot form carbonates from their aqueous solutions. E.g. when a solution of CrCl3 and Na2CO3 are mixed, then CO2 bubbles out of solution and Cr(OH)3 is formed. The same is true for iron (III). For copper (II) and nickel (II) this effect is less pronounced, but still, some carbonate is converted to bicarbonate or CO2 and a mixed hydroxide/carbonate is precipitated. All this does not say that carbonates of metal-ions like Fe(III) or Cr(III) cannot exist. It only says that these carbonates cannot be prepared from aqueous solution. IF a synthetic route of preparation of these carbonates could be found, then they might exist. But, I do not know of any such preparative route. For similar reasons, no chromium sulfide and aluminium sulfide can be prepared. When you bring together a solution of sodium sulfide and chromium chloride, then Cr(OH)3 is precipitated, and H2S escapes from the solution. However, Cr2S3 can be made from the finely powdered elements. So, although Cr2S3 cannot be prepared from aqueous solutions, it can be made by means of other preparative routes and this compound is perfectly stable.

This is a very common effect. Graphite rods tend to erode during electrolysis and pulverise. It is inert, but particles of graphite do not stick together very strongly. The current density should be kept below 100 mA/cm² for graphite anodes, or even better, below 50 mA/cm². At higher current densities, the erosion becomes really excessive. Also, oxygen formation at the electrodes enhances erosion strongly. This is the case, if the cell operates at too high a voltage. For good electrolysis, you need to work with solutions as concentrated as you can get them (allowing lower voltage for the same current and having less oxygen production at the anode) and you need to compute how much current may go through them by estimating the total area of the electrode, which is immersed in the liquid. With some form of current control the electrolysis cell can be kept in its correct operation domain. Using a voltage source of e.g. 9V or even 12V really kills your graphite electrodes.