# woelen

Senior Members

1864

1. ## Let's DO some science!

This is the place, where you can write about the experiments YOU have done, or are planning to do. This is not the place to write about something, which others have done, and it also is not the place to talk about some school lab, which you have to do. It should be about your own experiences, you have chosen out of interest. What we want to achieve with this forum is that people actually DO science and not only talk about science. Experiments can be described for all sciences. The most obvious thing may be chemistry, physics, electronics. But also mathematical experiments (e.g. computing and investigating properties of certain mathematical objects, recreational mathematics) and software experiments can be described here. Everything, which is fun, which is your choice to do, and which you want to share with others is welcomed here. The only guideline is that the described experiments must not involve illegal actions and if an experiment imposes a certain risk, then this must be stated explicitly.
2. ## Home made downs cell?

I don't believe that you made potassium when one of the ingredients was KNO3. The nitrate ion is a strong oxidizer, and certain at 350 C or hotter, it oxidizes (and ignites) all kinds of materials. Even much more inert compounds like wood, paper, sulphur and carbon are ignited, so you think that metallic K can survive an environment with nitrate ion in it?
3. ## Help! including heat in an equation

I also don't see what she is aiming at. Sometimes, reaction equations are given, with a change of energy: e.g. A + B --> C + D -100 kJ/mol But this only tells that this reaction occurs and that for each mol of reactants 100 kJ of energy is absorbed (or released if the value is positive). Most reactions also depend on temperature, but that usually is not put in the equation. Sometimes people put something above the arrow, such as "600 C", telling that the reaction occurs at that temperature, but this also is not the case in this reaction you mention. That reaction occurs at many temperatures, but its speed increases with increasing temperature. So, no, I don't see her point. Ask her to tell it, and please come back to us, telling what she means.
4. ## making nitric acid

Read a few posts above your post, and then you can read that it is possible to make HNO3 from NO2 + H2O, but there are some issues with that. I explained in more depth in post #162, so please read that (again??).
5. ## Experiments forum

To all moaners and whiners, let's talk a little less about science and DO more science. First DO and then talk! SFN needs more people who actually DO science and then the talking will follow automagically.
6. ## I wonder how the human race will die.

I agree with ScepticLance that mankind will not be wiped out by a change in the ecosystem of planet Earth. The only thing which could wipe us out is a cosmic disaster, such as a collision of planet Earth with a giant comet or rock (10+ kilometer diameter), or a fatal change in the energy output of the sun. I personally do not believe, however, that such a thing ever will happen (for religious reasons). Mankind will never be wiped out.
7. ## Cheap NaOH (from NaHCO3)

You could use charcoal, with a blast furnace. Inside this, you take a metal can (e.g. from food), with the chalk inside. After a few hours at glowing hot fire, it will have decomposed, but it indeed is a cumbersome thing to do at home. The problem is that many industrial large scale processes cannot easily be scaled down to a home situation.
8. ## Cheap NaOH (from NaHCO3)

Plain chalk is CaCO3, CaSO4 (and not Ca2SO4 as pointed out by YT) is gypsum.
9. ## Cheap NaOH (from NaHCO3)

The first step of NaHCO3 being converted to Na2CO3, CO2 and H2O is easy. the second step is amazingly difficult and not of any practical use. In order to decompose Na2CO3 to Na2O and CO2 you'll need temperatures of 1000 C or even more, not something you easily achieve at home. Even with a propane torch, directly blowing on the Na2CO3 at full blast you will not even come near the required temperature. No, this is not a decent way to make NaOH. One way to make NaOH could be to use CaO or Ca(OH)2 with Na2CO3. When both are dissolved, then CaCO3 precipitates and NaOH remains in solution. This method was known a long time ago already. Making CaO can be done by strongly heating CaCO3 (plain chalk). CaCO3 decomposes more easily than Na2CO3, although that still requires quite some heat.
10. ## Making chlorine

It definitely contains no perchlorate. Perchlorates don't give chlorine. In aqueous solution, perchlorate is very inert.
11. ## what is happening when sodium thiosulphate & hydrochloric acid react?

The above is correct, except that it is better to write ionic equations (in fact, HCl(aq) is non-existent, HCl does not simply dissolve in water, it reacts with water). Thiosulphate is the anion of the weak acid H2S2O3. This acid is very unstable, and slowly decomposes, giving H2O, SO2 and S. A more accurate description of what happens is the following: 2H(+) + S2O3(2-) ---> H2S2O3 (this is a quick reaction) H2S2O3 ---> S + SO2 + H2O (slower reaction, the solution turns turbid slowly) The Na(+) ions and Cl(-) ions do not participate in the reaction, they are spectator ions.
12. ## Collision theory - a few questions

Atheist, good that you pointed out. I was not aware of this. In my context, elastic does not mean "loss of energy", but just that the particles feel an increasing force, when they approach each other.
13. ## Collision theory - a few questions

Collisions usually occur in the liquid state or the gas state. Indeed, when collisions are not strong enough, then no reaction occurs. For some reactants, even a soft touching is sufficient to get a reaction, for others a hard collision is needed. The higher the temperature, the harder the collisions. Colliding is when the electrons of different molecules (or atoms) interact with each other. Collisions are not like inelastic collisions, such as pool-balls, but the electromagnetic forces gradually become stronger when atoms/molecules are getting closer to each other. So, collisions are more like elastic collisions. Think of it as if we have strong magnets, with only a single pole (in reality such magnetic monopoles do not exist) and these are randomly shaken through each other. The magnets repel each other and only when they are strongly forced into each other they actually touch, otherwise the collision is elastic and soft.
14. ## I wonder how the human race will die.

I believe that mankind will not be wiped out by any natural disaster, nor by any human-induced disaster. We can make things very difficult for ourselves, but that does not mean total extinction. I have severe doubts that we will ever get out of our solar system. Considering the immense distances between stars and the limitation of speed to the speed of light (and all other immense problems we will face when going to near-c speeds) I think that mankind will be effectively confined in its container, called the Sol-system . And I think it is good that we are confined to our solar system. If we would find another civilization, then either we would wipe it out (if we are technically superior to them), or they would have to wipe us out (because we are such a nuisance and threat to them that no other choice is left for them). If extraterrestrial intelligence exists, then it will be either MUCH more advanced than us, or at a MUCH lower level. Given the time scales at which life has developed (hundreds of millions of years) and given the timescale at which planets/stars are formed (billions of years), the chance that two intelligences are at precisely the same level of development would be extremely small. Even a difference of 1000 years is HUGE in terms of technological advance and what is 1000 years on a cosmic time scale?
15. ## Warmest winter on record

We did not have any winter. Summer lasted till the beginning of November (normally at the end of September it is done), and we had autumn-like weather till end of February, and now we have really spring (temperatures of 14 C and plenty of sunshine). I like the high temperatures, but in summer it may become unpleasant.
16. ## Human/Ape Crossbreeding

I have strong objections against this request for multiple reasons: This is a forum and usually, forum discussions are not in a mail box or a PM box. Taking this already somewhat 'on the edge' subject out of public discussion looks suspect. Why not discuss things openly? For the person, responding through PM there may be a risk of being involved in illegal/immoral activities. Of course, this is everyone's own decision, but take into account the risk of such involvements. Of course, we do not stop the PM-service for any user, involved in this, and if people really want to have a private discussion with Lordmagnus, then they are free to do so. But on the other hand, please take into account what I (and others before me) have written.
17. ## Reaction mechanism, formation of acid rain?

NO is a radical, it attaches to O2, forming O2-NO, the latter being unstable and loosing an oxygen atom and leaving behind an NO2 radical. The structure of ozone is not O=O=O, it only can be described by means of resonance structures. The mechanism for reaction of NO with O3 is quite similar to that for reaction between NO and O2. In the latter mechanism, nitric acid is formed, but the OH-group attaches to the N-atom through a single bond, so no H=O=N(=O)=O, but H-O-N(=O)=O.
18. ## Can I use the red phosporous as an oxidiser in place of KNO3?

Funny that you call it perverted. Chemical substances are not pervert, certain uses of chemical substances are pervert. For chemistry hobbyists, frequently the more 'pervert' (in your terms) compounds are the most interesting. Stuff that likes to react with many other things is interesting.
19. ## Can I use the red phosporous as an oxidiser in place of KNO3?

White P is MUCH more dangerous than red P. Red P on its own is not that dangerous. It is non-toxic and odorless. Red P, however, is very dangerous in combination with oxidizing chemicals. Even weak oxidizers can react very violently with red P. Commercial red P sometimes, however, has small amounts of phosphine. I also have a sample of red P, which is sold to me as 99.8% purity material, but it still has a smell of phosphine. Phosphine is very toxic, and the presence of that sometimes makes red P also somewhat toxic (not really badly, due to the very small amounts, but nevertheless....). The danger of red P lies in its extreme flammability and how violently it reacts with oxidizers (e.g. it catches fire at once, when immersed in an atmosphere of 30% chlorine or 50% bromine, mixed with air). White P is insanely dangerous and of a total different order of magnitude more dangerous. It is VERY toxic (100 mg of the solid will kill a grown up person of 80 kg) and even more reactive than red P. Touching it with your warm hand usually ignites it. For this reason, it must be stored under water. I have a sample of white P and while I transferred it from its container to a display vial, it already started smoking. That was quite scary! White P is not something you can easily play with at home, it is too dangerous. Red P is a nice chem to have, but not something for a starter.
20. ## Share your dreams and nightmares!

A nice start for a horror story, especially the thing with the girl in the garden Add the right music and the right tone/color and its the real stuff!
21. ## Can I use the red phosporous as an oxidiser in place of KNO3?

Vincent4e, do you really have red P? If I read your posts and see what you know about chemistry, then I can only give you one advice. Do not play around with the red P. The combination of red P and any oxidizer is insanely dangerous and you WILL get serious accidents if you mix red P with an oxidizer. Such mixes burn exceptionally violently and many of them easily ignite, even without lighting them. So, do not mix it with KNO3, KMnO4, KClO3, KClO4, etc. Please take this warning seriously.
22. ## electrolysis with AC ?

In my experiments, I also obtained a flocculent dark green precipitate of hydrous copper oxide/oxychloride/hydroxide. So, yes, I also had copper (II), suspended in the solution.
23. ## Can I use the red phosporous as an oxidiser in place of KNO3?

No, that will not work. You need an oxidizer, together with the sugar. If you do have red P, please DO NOT USE THAT in a rocket, combined with any oxidizer. A combination of red P and sugar is only fuel, but no oxidizer at all, it will not burn in a tube, when no air can access the mix.
24. ## electrolysis with AC ?

I once did the experiment, and well, things do happen. We have 50 Hz AC, and what is observed is formation of bubbles at both electrodes. I did the electrolysis with copper electrodes in NaCl. At both sides there were bubbles, and both electrodes are corroded. The bubbles are hydrogen gas. I also did the experiment with carbon electrodes and with 220 V AC (VERY DANGEROUS!!!!), using a very dilute solution of NaCl. The effect of that is formation of gas, and sometimes ignition of gas bubbles under water, near the electrodes. I slowly increased the concentration of NaCl, and at a certain point, I got a nice continuous stream of gas, with sparks of miniature explosions every few tenths of a second. These sparks most likely are due to ignition of gas mixed of H2 and Cl2 and/or H2 and O2. Using too high a concentration of NaCl makes the reaction too vigorous and quite hot. I strongly discourage someone else to repeat this, unless you are really experienced with working with high voltages in wet environments. This experiment is DANGEROUS, due to severe electrical shock risks. You cannot say I did not warn you!
25. ## more MSDS Exaggerations perhaps?

I know of an exothermic reaction, which can be started with water. Mix ammonium nitrate and finely powdered zinc and add a drop of water. Nothing happens. Mix ammonium nitrate, ammonium chloride, and finely powdered zinc and add a drop of water. The mix will react exothermically, and may even ignite with appearance of fire. So, the chloride plays some catalytic role, but I don't know which one.
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