woelen

HCN is more toxic than H2S, but both are quite toxic. Compare the numbers in the two MSDS's below. http://www.physchem.ox.ac.uk/MSDS/HY/hydrogen_sulfide.html http://www.physchem.ox.ac.uk/MSDS/HY/hydrogen_cyanide.html However, the stink bombs generate concentrations quite a lot below 1 ppm, so I see no real danger from them. Also, exposure to these things usually is just for seconds, maybe minutes. HCN is much more associated with danger, the bad side of science, poison etc. This is due to its historical misuse. Cyanides were used for poisoning purposes frequently and in WWII the gas is used for killing millions of Jews. If H2S were used for that purpose, than that gas probably would have the same negative associations in society.

Here, I agree with YT, H2S indeed is very toxic, but not THAT toxic, that stink bombs cannot be made with it. A solution of (NH4)2S or NH4HS is as toxic as H2S. It immedialely breaks down in NH3 and H2S, NH3 being the much less toxic part. So, the toxicity of ammonium sulphide is determined by the H2S released from it. In photography, Na2S is used as an important part of a sepia toner. People are always warned about the dangers of sulphide. What is stated, is that in a normally ventilated average sized room a safe amount of Na2S is approximately 2 grams. Even if by accident the entire amount were plunged into an acidic stopbath with subsequent release of H2S, then one does not need to worry about irreversible health risks. I myself take a lower safety threshold (appr. 250 mg), but if this kind of figures is given, then I would not worry about H2S-based stink bombs, which only contain mg's of the compound. Yes, 250 mg is sufficient to stink away every person in the house from every room. Also, H2S has no cumulative effects. Small time exposure does not lead to buildup of toxic effects.

It'll give much messier products. With that ratio the mix is strongly deficient in oxidizer, so the sugar will not burn completely. However, keep in mind that the optimal chemical mixture does not always need to be the optimal mix for rocketry purposes. It might be that the optimal chemical mix as according to my equation burns too fast for rocketry purposes. The amount of gas produced may be too much, etc. I'm not an expert on this, making a good rocket partly is chemistry, but constructional issues and speed of combustion also are very important factors for success. YT, could you please jump in ?? You probably better can help with the rocketry part.

The following reaction is a fairly good description. It is somewhat idealized, because you'll always have side reactions, where KNO2 and NOx are formed, but the main reaction is as follows: 5 C12H22O11 + 48 KNO3 ---> 24 K2CO3 + 55 H2O + 24 N2 + 36 CO2 If you mix very finely powdered KNO3 and sugar in the molar ratio's as described above, then you'll see that the reaction product is mainly a white solid, which, when immersed in an acid, gives a lot of bubbles. Side reactions produce carbon, some tarry/caramel-like material and some KNO2. I derived the reaction equation, based on the observation that the main solid product is potassium carbonate and the gaseous products, usually are H2O and CO2 from combustion and nitrate is reduced to N2. Given these reaction products, it is easy (though somewhat cumbersome by hand) to balance the equation. For the last thing I've written a nice program, which does the dirty work for me.

In the last equation, where is the CN-group going on the right side? The same for the nitrate. I think there is incomplete information to solve this. These equations cannot be balanced.

That is indeed impressive, such a large expansion. I did not notice this, because I used a test tube without marks on it. Nice to read that you get rid of all kinds of impurities. If you do this well, then you can get rid of 100% of all insoluble impurities and surely 80% of soluble impurities. But, I'm quite sure that in the toluene solvent, most impurities will be insoluble. With a single recrysallization, where the hot liquid is decanted from insoluble crap and subsequent 24 hour outgassing of small sulpur crystals on a dust-free place, you'll get VERY pure sulphur.

Yes, that works quite well. You can also make silver directly out of it. Dissolve some vitamin C (e.g. from tablets) in water, filtering out the white insoluble stuff. Add NaOH to this and then add your white AgCl. This stuff becomes black very quickly. Rinse well with water in order to remove impurities. No need to dry. Simply add HNO3 to it again and you have AgNO3 again.

For KFC, I fully agree with you. In general, I do not agree. If you really know what you are doing and you have the suitable equipment and the suitable chemicals of known composition, then you can make dangerous compounds. I've made quite some dangerous things, like pure bromine, hydrogen cyanide and even stuff like trinitromethane or silver acetylide nitrate. I do not say that I cannot get accidents (sometimes things go wrong), but I always work with very small quantities and plan beforehand, what to do if something goes wrong. If that scenario becomes reality, then I know what to do and then the consequences are only minor.

Making hydrazine out of chlorine bleach and ammonia is not an easy process. The reaction conditions need to be very specific and once you have the hydrazine, you need to isolate it, which is quite hard as well. Isolating pure hydrazine is next to impossible in the homelab, however you can fairly easily isolate the salfate salt of this. The hydrazine synthesis surely can be done, but it is not something to start with if you do not have any experience. Beware, hydrazine is carcinogenic, and also its salts are. Also, the nitrosamines, formed in the reaction between bleach and ammonia are carcinogens as well. KFC, I've mentioned it before, but you seem not to be listening very well. Just shooting random questions at us over here does not make you a better chemist. Grab a good book on the subject and start with the basics. Just mixing chemicals and see what happens is not smart at all. It may hurt you. Besides that, it is much more fun, if you really understand what is going on.

Making some common gases with easy to obtain chemicals: Oxygen (O2): Take hydrogen peroxide and add some catalyst. A good catalyst is liver, manganese dioxide, but also green patina from copper metal. Hydrogen (H2): Add aluminium metal to dilute hydrochloric acid (10% HCl, do not use higher concentration) and add a small amount of a copper salt (you can make that by electrolysis of hydrochloric acid with copper wire used as electrode). The copper salt need not be isolated. Just perform the electrolysis in 10% HCl, until the liquid has a nice green color and then immerse some Al-foil. Instant and violent production of hydrogen gas. Without the copper, the reaction is MUCH slower. Chlorine (Cl2): Mix some bleach and dilute hydrochloric acid. BE CAREFUL. DO THIS OUTSIDE. Chlorine is a very interesting gas (it is green and it supports combustion of many compounds with a red flame), but it is very poisonous. If you perform this experiment, really do this outside and only use small quantities. Carbon dioxide (CO2): Mix some baking soda with dilute hydrochloric acid. Instant vigorous production of carbon dioxide. Sulphur dioxide (SO2): Add some sodium sulfite (from photography shops) to dilute hydrochloric acid and heat a little bit. Bubbles of SO2 are formed. It is also best to do this outside. SO2 has a pungent odour and is irritating. It is not as toxic as Cl2, but still it is quite irritating. And last but not least, ammonia, NH3: Mix some solid NaOH (caustic soda, drain cleaner) with a small amount of solid ammonium sulphate fertilizer (you can use the plain stuff, without the need to purify) and add a few drops of water. If the reaction does not start within a few seconds, then heat a little. The mix will start bubbling and a lot of NH3-gas will be evolved. This is a funny gas. Perform this experiment in a small bottle, loosely capped and wait, till the reaction stops again, then tightly cap the little bottle. Next, keep it under water and open the cap. The water will be sucked into the bottle quickly, as the NH3 is VERY soluble in water. Making ammonia gas can best be done outside. NH3 has a very pungent odour. It is not very toxic, but it is highly irritating, just as SO2 (although its smell is very different).

Buying a good entry-level book may also be an option. Just experimenting and mixing things, without real understanding is not that interesting. The experiments really become much more interesting is one understands what is going on. With some basic understanding you'll also see that a lot of interesting chemistry experiments can be done already with simple household stuff and stuff from hardware stores.

That explanation that you read probably was about electrolysis of water with lead electrodes and sulphuric acid added to the water. This is the basic principle behind a lead/acid battery, as it is used in cars.

In metals, there is a so-called conduction band. Quantummechanically, inside an orbital, an electron can have a certain energy state. There are multiple orbitals in which electrons can be, but the energies associated with these are very distinct. In a metal, multiple orbitals around different atoms combine to form a large number of very large orbitals, with energy levels very close to each other. So, in a piece of metal, there still are discrete energy levels, but there are many many energy levels, all inside a band between a lower and upper bound. So, it looks as if there is a continuum of energy levels. Because the energy levels are so very close to each other, electrons can easily move from one level to another level. Because the electrons in this way can move to another orbital very easily, it makes them mobile and hence a metal is a conductor. The following link explains the semi-continuous behavior of metals (and semiconductors): http://www.ece.utep.edu/courses/ee3329/ee3329/Studyguide/ToC/Fundamentals/Carriers/density.html This is the entire site, which nicely explains more quantum mechanical concepts: http://www.ece.utep.edu/courses/ee3329/ee3329/Studyguide/ToC/Fundamentals/index.html

You cannot simply tell the flame temperature of any burning chemical. If you simply light some liquid, or when it is sprayed out into the air from a burner, there can be quite different temperatures. A nice example is the gas stove. The blue flames have a totally different temperature than the orange flames. So, it depends on how it is burnt. However, in any case, the temperature will be at least a few hundreds of degrees Centigrade.

KFC, I understand that you want to learn more about chemistry and pyrotechnics, but please do not behave like a dumbass, shooting random one-line questions at the people over here, hoping for a reply. It does not add any understanding. If you really want to understand things, first browse around, read threads and search for topics which are interesting for you. There also is a lot on pyrotechnics on other places, such as Usenet's rec.pyrotechnics groups. Have a look over there. There are tons of info of really good people, who know what they are doing. By reading that you learn a lot more than by shooting random questions. http://groups.google.com/group/rec.pyrotechnics

YT, you can take 5d electrons together. The order in the comma separated list does not tell anything about the order in which electrons are added to the atoms, when traversing through the periodic table. Indeed, explaining why certain orbitals are filled first and why there are some irregularities, such as V/Cr and Ir/Pt, cannot be explained by means of simple rules. When precise quantummechanical computations are performed, then you'll see that the observed electronic configurations are energetically the lowest (and the most stable). So, for precise detailed explanations, one has to resort to complicated and detailed computations, there are no simple rules anymore, which can explain all these things.

Ah, that picture makes things more clear. You used copper electrodes with this, otherwise you would not have this orange material. This orange stuff mainly is Cu2O (copper (I) oxide). It is formed by the oxidation of copper at the anode (Cu + 2Cl(-) --> CuCl2(-) + e), the e taken up by the anode. CuCl2(-) in turn reacts with hydroxide, formed at the cathode: 2CuCl2(-) + 2OH(-) --> Cu2O + H2O + 4Cl(-)

The yellow color probably is due to dissolved ClO2. That gas, when dissolved in water, gives a very intense yellow/green color to the solution.

This is why certain chems are becoming more and more difficult to obtain in the Netherlands. Here are some k3wlz in action : http://video.google.com/videosearch?q=explosieven This was posted on a Dutch/Belgian chemistry forum by those k3wls and wow, the flaming response was really great. On that forum they hate k3wls like hell! After this post I've never heard of them again on that forum . But to be serious again. In the Netherlands it is this kind of people who spoil the chemistry hobby and pyrotechnics hobby. I like a nice fireworks display, but what these boys do is just destroying things. No fun at all. In k3wl-dutch: Kn4LLUh & r0K3n :mad: .

I would call this a physical process, but indeed, it is a little bit on the border. Two kinds of energy are involved, lattice energy and hydration energy. When a solid dissolves, then energy is needed to break down the lattice, in which the molecules (or ions) reside. On the other hand, energy is released by the hydration of these ions. An example: NaOH contains ions Na(+) and OH(-). On dissolving you have three processes with a certain energy balance: Na(+)/OH(-) + energy -----breakdown of lattice----> Na(+) + OH(-) Na(+) ----solvation----> Na(+)(aq) + energy OH(-) ----solvation---->OH(-)(aq) + energy For NaOH, the balance is positive, especially the part of solvation (hydration) of OH(-) gives a lot of enerhy. For NaCl the balance is slightly negative. For NH4NO3 the balance is even more negative. In the instant cold packages, I would not speak of a real chemical reaction, but one could regard the solvation process also as a chemical reaction. ================================================================================ Dissolving of some compounds, however, really is a chemical reaction. If you dissolve anhydrous CrCl3 in water, then there is a real chemical reaction. The lattice contains molecules (almost purely covalent units) of CrCl3. When these are dissolved then the following process occurs: CrCl3 ---solvation-----> Cr(3+)(aq) + 3Cl(-)(aq) Here, the covalent units are split in ions. This is a true chemical reaction and that also is clear from the properties of CrCl3. CrCl3 is a pink/blossom solid, while the usual hydrated form is a dark green solid. Other examples of such chemical reactions are: dissolving of H2SO4, dissolving of solid anhydrous NiSO4. Dissolving of hydrated CrCl3.6H2O again can be regarded as a borderline process between chemical and physical change, just as dissolving of table salt.

I'm quite sure you'll have a very hard time finding a compound, which you can safely eat and which on the other hand has the cooling effect you want. If I were you, I would stick to the good old ice cubes .

The solids in the inner bag dissolve in water and due to this, the water cools down. Some compounds take up quite a lot of heat while they dissolve. You can experience this effect yourself somewhat by dissolving a lot of table salt in water. Even better is dissolving ammonium nitrate (from fertilizer). You certainly will notice the cooling down. The mixture in the bags is chosen such that the maximum amount of solid can dissolve in water at a fairly constant rate, the solids being such that a lot of heat is taken up. The opposite effect also is quite common. If you dissolve e.g. sodium hydroxide (drain cleaner), then you'll notice a strong heating of the solution.

Toluene can be used to make beautiful crystals of sulphur. You can also purify sulphur with it easily. http://woelen.scheikunde.net/science/chem/exps/S+toluene/index.html Try to scale up this experiment and see if you can make beautiful crystals of sulphur.