woelen

Look at it in another way. As long as |y|< a, then dy/dt > 0. So, y can only increase. Given the initial value y(0) = 0. The solution moves towards a as time passes on, but at t = pi/2, the solution reaches y = a, and from that point it remains there. So, the solution is as follows: y(t) = a*sin(t) for 0<= t <= pi/2. y(t) = a for t > pi/2 This is a continuous function of time. This statement is not true. The solution does not move asymptotically to a, as opposed to the solution of dy/dt = a - y, it actually reaches a at time pi/2. Look at the explanation below. When y is very close to a (let's say y = a - e, e close to zero, but positive), then dy/dt = -de/dt = sqrt(a*a - a*a + 2*a*e - e*e) because e is very small, the following approximation is valid: -de/dt = sqrt(2a) * sqrt(e) or: de/dt = -sqrt(2a)*sqrt(e) de/sqrt(e) = -sqrt(2a)*dt ==> 2sqrt(e) = -sqrt(2a)*t + C, with C a positive constant. You see that sqrt(e) goes to zero linearly with time and e itself goes to zero quadratically. Hence, when y is near a, then y will reach a quadratically, and that is exactly what is the case near the top of the sine curve. Once, this point is reached, y will stick there forever and the system becomes stationary.

The drawing indeed is correct. YT, using 5 V can be done, but then without the resistors. However, as I stated before, you don't have the benefits of current control in that case. In the beginning the current probably will be too high and at the end it slows down too much. With the suggestion I gave, the current can be controlled much better. It will start of somewhere just below 2A and at the end it will still be above 1.5A. The most ideal thing would be a real current source instead of a voltage source, but that requires more electronics (we discussed that before, e.g. use of an LM317). The resistor network in series with a higher voltage like 12V provides sufficient current stabilization. Of course, with this setup, there will be somewhat more power consumption, but for a home/hobby setup that is no concern. In an industrial setup I would advice something totally diffierent, where energy consumption is minimized. For a home setup, I, however, advice the setup, which has the most consistent results over extented periods of time and which has the same effect for almost all kinds of electrolytes used.

YT, that looks really great. That is an experiment I'm certainly going to repeat! How big is that white tub in which you have the liquid? Is this still the 5 cm you mentioned in your previous post?

What did you do precisely? You say you didn't attach the resistors ? If you apply 12 V directly, then you are ruining all your stuff! That really does not work. You can even kill your PSU without proper fans/cooling. Please be more precise and follow the direction precisely. The circuit should be as follows: Take your 5 resistors and solder them in parallel. This makes one big combined resistor. Next, take a wire and connect this to the + of the PSU. At the other end of the wire, connect one side of the combined resistor. At the other end of the combined resistor, connect another wire. At the other end of that second wire, connect the graphite anode. At the - of the PSU, connect a wire and at the other end of that wire, connect the cathode (which may be a copper plate, iron plate, but also may be graphite). With this setup, you dip both electrodes into the liquid and let it run for a few days. That should work and should not melt down anything, nor make a shit out of it. Occasional replenishing of water may be necessary. The liquid will become warm, but not really hot. The resistors can become quite hot, but that is no problem as long as they are at least 5 W. They are designed for that. The graphite anode may erose considerably and you'll get black carbon powder in the liquid, but that should not do any real harm. Remember, the total graphite surface, in contact with the liquid should be at least 20 cm², preferrably even 40 cm². Optimal current density is 50 mA/cm², but 100 mA/cm² still is acceptable, although that will erode your anode somewhat faster. You know how to compute/estimate the total contact area?

@[w00t]: Your PSU probably is quite old. Indeed, no wires, as I mention on my website. But... I see yellow output wires, so, you certainly have 12 V output. If your PSU powers up, just by switching on, then you do not need to do all the difficult things, I write on my site. A modern ATX-PSU, however, requires these things to be done, otherwise it does not power up, even if connected and switched on. So, just use your PSU. @YT2095: Your method may work, but these resistors are not that expensive. If you buy 5 of them, then you'll probably only need US $3 (GPB 2). Over here, I pay EUR 0.60 for one of them, but mainland Europe is more expensive with these things.

No, the phosporous in the phosphate (and also in the ATP, ADP and other materials) has nothing to do with white or red P. If I burn red P, then I get P2O5. If I burn white P, I also get P2O5, and the latter is not different from the former. Both give phosphate with water and alkalies and these phosphates are just phosphate and one cannot speak of 'phosphate, derived from red P' and 'phosphate, derived from white P'. Once you have phosphate, one cannot tell anymore from which allotrope of the element it is made.

Of course! More current --> more electrons per unit of time --> more chlorate per unit of time. I don't want to blame you, but this question gives me the feeling that you do not really understand what you are doing. Do you have basic knowledge of electronics? Without that, it indeed may be quite hard to understand the second part of the page I wrote. The load resistors have nothing to do with fuses and protection of the power supply. They are there for controlling the electrolysis process. The resistors make the circuit somewhat controlled and provide negative feedback. If the required redox potential over the electrolyte increases, then the current tends to decrease. But, when that happens, the voltage drop over the resistor also decreases and more voltage remains available for the electrolytic cell. Hence, the current is stabilized. You just want chlorate production without hassle and difficult math? You do not need precise control over your power supply with selectable currents. Then do the following: Prepare a power supply, as I describe in the webpage in the text before the "Additional wiring and resistor networks" section. Next, buy yourself 5 ceramic resistors of 22 Ohm/5 Watt and wire them in parallel (this makes appr. 4.4 Ohms of resistance). Put these parallel resistors in series with the 12 V supply and the electrolytic cell. With this plain simple setup you'll have a current between 1.5 A and 2 A. That allows you to make around 100 grams of NaClO3 in 4 days. You'll need parallel electrodes though with such a current, or you need large electrodes. A simple battery rod will erode way too fast with a current of 2 A. I'm not talking about wires, which connect to the 240 V input. If your PSU is a normal PC power supply, then you'll see a lot of wires coming out, with plastic connectors, which you normally connect to a mainboard. Those are the wires which you need to modify. PLEASE DO NOT FIDDLE WITH THE 240 V WIRES. Know what you are doing!

One night is way too short. For 1 mole of NaCl to be converted to NaClO3 you need 6 moles of electrons (at least, probably more, because you loose chlorine into the air and also some chlorate is back-reduced). In order to obtain 1 mole of electrons and supposing you have 1 A of current, you'll need almost 100000 seconds. Roughly speaking, current times seconds must be 100000 for 1 mole of electrons. For 1 mole of NaClO3 you hence need 600000 Ampere-seconds (a.k.a. Coulombs). One mole of NaClO3 is just over 100 grams. So, for 100 grams of NaClO3 you need 600000 Ampere-seconds. With a current of 1 Ampere this means 600000 seconds, which is over one week of current, full-time, 24h per day. With 2 Ampere you still need almost 4 days of current for 100 grams of NaClO3. You see? Be patient and let the whole lot bubble for several days. Occasionally check your cell and if necessary, sometimes add a little water. It, however, is much better to use a current source. As the concentration of chlorate increases, a higher voltage is needed. With a fixed voltage, initially you will have too high a current density (excessive corrosion and formation of oxygen+acid instead of chlorine) and lateron the current density becomes too low. Using current instead of voltage makes the operation of your cell much more consistent. Current determines how many electrons are produced per second, not voltage. I have done a project on this with a modified PSU and a resistor network. I would say, read the theory and try to understand what a current source is and what characteristics such a beast has. For electrolysis experiments this is much better. http://woelen.scheikunde.net/science/chem/misc/psu.html Also keep in mind that with graphite electrodes the current density should not exceed 100 mA/cm². With the graphite rods of batteries this means that using a current well over 1 A you obtain a too high current density, which results in excessive erosion of your rods and production of oxygen+acid instead of chlorine.

Ammonium Nitrate: Not really toxic. Nitrate ion, however, to a small extent is converted to nitrite, and that in turn is converted to nitrosamine compounds, which are carcinogens. Ammonium Chlorate: Oxidizer. Produces chlorine and chlorine dioxide in your stomach, which damages the inside of your stomach. When this comes in the blood stream, it may also oxidize haemoglobin irreveribly, making it unsuitable for exchange of oxygen. Ammonium Perchlorate: Not really toxic. Perchlorate ion does not react in the body. Potassium Nitrate: See ammonium nitrate. Potassium Chlorate: See ammonium chlorate. Potassium Perchlorate: See ammonium perchlorate. Cadmium: Affects metabolism (resembles zinc) and may replace zinc at certain places. I'm no expert on this, but this appears to be VERY dangerous. I do not know why. Chlorine: Corrosive to tissue. Destroys tissue and that is the main toxic effect (local toxicity). Fluorine: As chlorine, even worse. Besides that, fluoride ion, formed in the reaction, interferes with your bones. It forms fluorophosphates, instead of normal phosphates or hydroxyphosphates. That makes your bones weak and brittle. It also affects metabolism of many cells, mainly due to formation of fluorocomplexes. So, even fluoride is very toxic, while the other halogenide ions are not or only to a very limited extent. White Phosphorus: Intensely poisonous. I do not know why. Arsenic: Intensely poisonous. Its main mode of operation is replacement of phosphorous by arsenic (these elements form very similar compounds), but the properties of these arsenic compounds are not precisely the same as the properties of their phosphorus counterparts. This messes up many metabolic processes in our body. Phosphate-compounds play a major role in metabolic processes and one should not tamper with that. Hydrogen Cyanide: Cyanide forms a complex with iron very easily and does this irreversibly. It acts on iron-containing enzymes, which support the transfer of oxygen (not mainly haemoglobin, but other compounds). Mustard Gas: Very poisonous, but I do not know why.

Over here in the Netherlands petroleum ether (bp 40 .. 60) is sold in many drugstores in small 100 ml bottles. It is very easy to obtain. Probably it is similar at your place. Every supermarket sells the alkane mix of 100 .. 140 boiling point range. The 60 .. 95 stuff can be purchased at pharmacies, but that is a little more difficult. They do not easily sell to all kinds of people.

A fuse is a pyrotechnic device and probably will be subject to much more inspection. In the Netherlands that would certainly be a problem, I do not know about the UK though. I also ordered red P from kno3.com, and that was no problem at all, but I certainly dare not order fuses (or whatever pre-made devices for pyrotechnics). A parcel with fuses inside certainly will be investigated in more detail when it goes through the parcel-scanner. In fact, it is good that kno3.com did not ship the fuses and the other chems in the same parcel. In that case, you probably would have to wait for all three items. The red P from kno3.com is not really cheap, but it has great purity. I have the stuff and the label tells it is 99.8% pure. It dissolves in a solution of Br2 in water, without leaving any residue and that indeed indicates very good purity. I have another source of red P and that source only sells it at around 96% purity, the rest being crap like sand (??), phosphate remains, fine carbon and other impurities. That other red P leaves quite some residue, when dissolved (and reacted) in a solution of Br2 in water. For pyrotechnic experiments that is of no concern, but it is a concern in more precise chemical experiments.

You're right, it only is called "ether" because of its low boiling point and volatility. It contains lower alkanes only (C5 .. C8).

Even with solid NaCl and concentrated HNO3 you won't get HCl gas. You'll get chlorine and nitrosylchloride instead, together with water.

There is a compound, called petroleum ether and it is not naphta. I have purchased a liter of this and it is a mix of hexanes, pentanes and octanes, with a boiling trajectory of 40-60 C. These simply are alkanes and contain no double C=C bonds. It certainly does not contain olefins, like naphta does and it also does not contain aromatic compounds. Another name for this compound is "ligroin". Sometimes, however, ligroin also is used as the name for a very similar mix of alkanes, but now from heptane to C10H22 with a boiling trajectory of 60 - 90 C. Finally, there is a compound called washing benzine, also a mix of alkanes, with a boiling trajectory of 100 - 140 C. All three liquids are very pure completely saturated liquids, which do not leave any residue on evaporation and contain no oily compounds. Ideal as non-polar solvent and ideal for cleaning and degreasing. There also is something called white spirit. This mainly consists of naphta, but also contains methylated benzene derivatives and olefins. It is much more reactive than the alkane mixes, mentioned above, and also more risky from an environmental point of view.

Red P does not dissolve in any solvent. Red P forms macroscopic molecules, like graphite, diamond, boron and silicon. These compounds cannot be dissolved without chemical reaction. This can also easily be explained. Dissolving of these compounds means that bonds are broken. This is in large contrast with sulphur, white P and red selenium. These form molecules (S8, P4, Se8), which can be separated more easily, without the need to break chemical bonds. So, for these, there are quite some solvents. Red P can also be stored indefinitely, if stored in a tightly capped container. It is not poisonous and it is quite stable. Only at elevated temperatures and in contact with elemental halogens (especially Cl2 and Br2, but to a lesser extent, also I2) it is reactive. Otherwise it is remarkably inert.

What really happens is that some aqua regia like liquid is formed. HNO3 oxidizes HCl to Cl2 and ONCl. When the liquid is allowed to stand for some time, then it turns yellow, due to the mixed color of light green Cl2 and orange/brown ONCl.

I expect it to be NaNO3. NaNO3 is almost insoluble in concentrated HNO3. With addition of excess HNO3 you get a LOT of NO3(-) ions and then the common ion effect makes the solubility of NaNo3 lower. On the other hand, if you add conc. HCl to a solution of a sodium salt, then you get a precipitate of NaCl. NaCl is almost insoluble in conc. HCl. I'm, however, not 100% sure with the NaNO3. This is what I expect, but if you really want to be sure, I would say, collect the precipitate, let it dry and mix it with some S + C and see whether it makes kind of BP. If this is the case, then it certainly is (mostly) NaNO3.

Of course in a lab the chlorinated and other solvents need to be collected separately. That is a good practice. Over there, quantities can also be quite large. However, at my home experiment, I only used a few ml total of liquids. The MSDS-info and environmental info from many sites frequently give the worst case scenario and if you read those things then everything is explosive, poisonous and flammable to an extreme extent. There are risks involved in chemistry, but frequently these risks are exaggerated, especially in official documents on safety, such as MSDS's and university safety precautions. In fact, I tried many incompatibilities from MSDS's by mixing incompatibles on-purpose in small quantities. In 9 out of 10 cases, nothing happens at all when the so-called incompatibles are mixed. Usually a lot of other conditions must be fulfilled before something really happens (such as with actone/chloroform: alkali must be present) and then usually, the thing which happens only is a pale shadow of what is described in the document. Where the document mentions explosion or fire, I observe some increase of temperature...

From where do you have that info? I've done that experiment quite a few times. Mixing acetone, chloroform and a base (e.g. NaOH or KOH) is a well-known way of making chlorobutanol (a.k.a. chlorbutol), a certain drug with a strange but quite pleasant and attracting sweet/mint odor, which makes you feel drunk. I only breathed the vapor of the drug, I did not eat some of the white solid (eating a few 100 mg of that stuff is the supposed route of intake). The reaction is fairly exothermic, but certainly not explosive. With a mix of room temperature 50% acetone, 50% chloroform, to which an equal volume of a solution of NaOH in ethanol is added, the liquid becomes quite warm (I estimate 50C or so), but not so hot, that I could not bear the effect on my skin anymore. Of course, when someone mixes hundreds of ml of acetone with similar amounts of chloroform and adds a strong base, then you may have bad surprises. The reaction is specific for chloroform. I also tried with trichloroethene and dichloromethane. These do not react with acetone in the presence of NaOH. The NaOH is a catalyst in the reaction with chloroform, it is not used up. Apparently, it forms a CCl3(-) ion, itself being converted to water. The CCl3(-) ion in turn attacks the acetone to form CH3C(O-)(CCl3)CH3 and the O- reacts with water (from the OH(-) and the CHCl3) to form OH(-). The net result is CH3C(OH)(CCl3)CH3. If someone does this experiment, please do not ingest the stuff you make! That would be a most stupid thing to do. You have a severe risk of poisoning yourself with chloroform! It is, however, quite interesting to smell this compound, it has a really fancy odour and a strange 'refreshing' and 'opening' effect on the nose and throat! Be prepared, however that this stuff is not something to play with lightly. It makes you feel like you've drunk too much and I would not go out and drive a car anymore if I had sniffed some of the vapor.

Darkblade is right. It is silver fulminate. These in fact are normal small pieces of stone (gravel), which are covered by a VERY tiny layer of silver fulminate. The pure compounds is exceedingly sensitive and even only 100 mg of the pure compounds gives a very loud boom.

It is a chlorinated hydrocarbon (it's also called "solventane") and I bet that it has carcinogenic properties. Its direct toxicity probably is not that high, but it may have some nasty longterm effects.

Wow, this sounds really interesting! I've never heard of this before. How did they discover this? Is it possible to have only one of the ions in solution? If I make the solution very acidic, then still the liquid is blue, and not green or violet. Wouldn't the ion [ce]Cu(H2O)5(OH)^{+}[/ce] be totally converted to [ce]Cu(H2O)6^{2+}[/ce] in non-coordinating strongly acidic solution. I've done this experiment with HNO3 and H2SO4, but with both the solution remains as blue as without the acid. With HCl, the solution turns green, but that is due to formation of the complex ion [ce]CuCl4^{2-}[/ce].

Almost all organic solvents are more or less toxic. Some are minor toxins, such as ligroin, acetone, diethylether, ethanol. Some others are more toxic, such as toluene, xylene, methanol. Some are very toxic, such as carbondisulfide, most chlorinated hydrocarbons. However, all organic solvents must be treated with care. Repeated breathing of the vapors may lead to CNS-depressions, dullness, fatigue and other unpleasant things.

If you want mercury, try http://www.kno3.com. They sell it at 380 gram quantities for a very reasonable price and they are UK (Scotland) based.

I have built a small "fume-hood" from a kitchen fume exhaust, which has its own connection to the outside. I removed all filters and the like, in order to have maximum air flow. The amounts I use in my experiments are so low, that I'm not afraid of poisoning neigtbours or animals on the roof of our house. A real fume hood most likely will have even more powerful fans and also requires spark-free fans, but the thing I made, serves very well for the experiments I do. I, however, do not perform large syntheses with flammable or very poisonous volatile liquids or gasses inside. If I do an experiment, which gives off really large amounts of noxious fumes, then I do the experiment outside on a windy day, such that the fumes are not blown towards the garden of our neighbours.