raivo

H3BO3 can be separated from Na2SO4 by fractional cristallisation. If temperature is higher than 32C then Na2SO4 crystallises without water molecules and at 35C has solubility of 49g in 100ml water. Boric acid is far less soluble 7.6g for 100ml water at 35C. You need to evaporate such amount of water that all Na2SO4 remains in solution. 35C seems to be best temperature for collecting your boric acid.

If you plan to electrolyse molten salts then NaOH is easyest to do because its melting point is relatively low ( 322C ). NaCl can only be used if it is mixed with CaCl2, otherwise its melting point is so high that sodium will evaporate instead being liquid. Argon is relatively cheap ( it is sold for industry in cylinders like oxygen or acetylene ) but to find supplier who wants to selle it in small quantities may be hard. There may still be safer ways to make alkali metals at home. That is electrolysis of salt solutions if solvent is not water but some other liquid that will not react with alkali metals at room temperature. It has been done ( in fact it happens in some lithium cells ) but suitable solvents (Propylene carbonate, DMF, DMSO) are hard to get and need to be absolutely water free to be used for this.

HCl makes azeotrope with water. This boils at 108.6 C and contains 20% of HCl and 80% water. If you start to boil hydrochloric that has more than 20% concentration you get at first lot of gaseous HCl. When concentration changes to 20% HCl and H2O will evaporate together and concentration does not change any more. If you boil long enough you get empty pot.

I can only say that KOH, I2 and KI will not make complexes with ethanol. Alternative examples are some bromides. ( MgBr2 * 6C2H5OH and LiBr * 4C2H5OH can be made by crystallisation. )

Sand (SiO2) contains 53% of oxygen.

It is possible to use that difference in solubilities to get almost pure product. You dissolve certain amount of mix in hot water. Then you cool that solution. If you choose quantities in certain well thought way then only one of salts will crystallise and another remains in solution. In practice some experimenting is needed because solubilities in such complex solutions are not exactly the same as in distilled water.

Yes, jdrug, this is all right and also what bud said about safety. Concentrating of sulfuric is surely not first lab boiling experiment one should do. Most important is to be aware of bubbles that can spray you or nearby things with hot acid. Even soft boiling can suddenly splash. You should be ready for sudden breaking of glassware (especially on heating). All lab setup must be done in such way that even in worst case nothing can fly into your face and any hot caustic liquid that accidentally sprays out will be noticed and easyli cleaned after work.

I suspect that right place to ask for battery acid is those auto or agriculutral machine stores that are mostly for repair parts and cheap stuff. I never had problem finding battery acid in europe. Battery acid is easy to boil to 80...90% concentration. Boiling temperature increases as concentration becames higher, so you need heater that can heat liquid at least to 200C (this is gives 80% conc), for 90% you need temperature no less than 270C. You need thermometer to measure temperature. At 280C H2SO4 starts to decompose so you get lot of white toxic fumes and lose part of your product if you go over that point. Note that by white fumes you can not decide what concentration or temperature is because fumes start to form at far lower temperatures.

I do not know answer to your question but it is rather common when two molecules connect to make hydrate or complex of some kind. Table salt CAN be hydrated but not at room temperature. Near the -20 in high humidity NaCl*2H2O may form. Water is not only solvent that may get bonded to salt molecules. Many organic solvents do the same in specific conditions .

Many thaks to Technologist for link! It explains a lot.

Can anyone explain how EDTA is used for titration? I read somewhere that EDTA reacts with metal ions and color of erichrome black indicator changes when there is no free EDTA any more. Right? Are there other indicators that can be used for titration with EDTA? Is there way to tell by such titration what metal ions those were that reacted with EDTA?

Yes, methanole poisoning took more than 68 lives during one month in Estonia at 2002. This was due of one small illegal distilling plant. Possible methanole content in home distilled alcohol is surely one of reasons why home distillation is illegal. That incident with cyanide poisoning was somewher in southern Russia at seventies. (I have lost exact record) Russia of course was part of Sowiet Union at that time.

As much as i know seeds from fresh fruits never contain cyanides but i have heard of one cyanide poisoning case in former russia. Death toll was nearly 20. Victims drank lot of wine that was made of plums that also contained stones during all process of wine-making.

There are some trully harmfull substances but many of those that are within last tens of years found as harmfull are not remarkably dangerous in reality. When substance is called toxic or carcinogenic in some cases it just means that if 1000 people deal a lot with it then 30 of them will get after years some dissease that is got "only" by 10 of 1000 in case of ordinary people. But 970 of 1000 did not get any disease. So what is proven here?

You may look for various drain cleaners. Some of cheapest are just solution of NaOH. Soap-making kits are also good source of lye. It can be made at home by boiling soda and lime. For this you need some vessel that will not break by uneven heating. You need something that protects eyes and hands in case things go wrong. Also you need pretty good filtering equipment. So i think better idea is do go to supermarket and look around.

I think that Na+ goes to negative electrode, reacts with water (as you expect of sodium) and releases H2 and with this also changes back to NaOH. On positive electrode excess OH- ions probably release some oxygen to make H2O again. I supose it is something like that, but theory is not my strongest point. But solution of NaOH is best of all electrolytes i have experimented with. No byproducts are formed, amount of NaOH will not decrease with time, electrical conductivity is better than with NaCl or H2SO4 and any kind of stainless steel can be used as electrodes with no corrosion or dissolving of electrode material. You can try it yourself.

Best electrolyte for producing H2 is solution of NaOH. You need concentrations less than 10%. Whatever you use you need lot of current to make any reasonable quantities of gas. Faradays Law says that 28.7 ampers of current must flow through electrolyte within one hour to move one gram-molecule of H+ ions to the negative electrode. Its not very realistic with ordinary battery even regrading that you may use 10 times less of current if it flows within 10 hours. Its good if voltage on electrodes is keept as low as possible because anything that is higher than some volts is useless for electrolysis and will just heat your solution up. Also beware that hydrogen tends to form explosive mixtures with air! Chlorine (if you use chloride electrolytes) is not particullary dangerous because its smell is so nasty. In case you want to get chlorine, strong currents are even more essential because first grams of it will dissolve in water. This is reason why you did not see bubbles on one of electrodes.

I think that most common problem with other nitrates is that they tend to contain water. Its remarkable how fast KNO3 will dry. No many salts do as well. There may also be other problems. Once i tryed to make calcium nitrate crystals ( by mixing Ca(OH)2 and NH4NO3 in water ) It appeared quite hard task because of solubilty properties that calcium nitrate has. At first i got some kind of syrop and ended up with glass. You may also test decomposition properties of nitrates by heating some small amount ( like 1g ) with torch and exploring what exactly happens. For example NH4NO3 and KNO3 will behave completely different way. It would be interesting to see your results.

If tube with gas goes into the liquid then you need gas source that has very even gas flow, preferably with controlled strength. Otherwise solution tends to rise in tube and flood up your gas generator. I usually do such kind of experiments not puting tube into the solution put slightly above the surface of solution. This is usally enough to get thing working and no need to stay nearby and watch all the time.

"Best" depends on what exactly you want to do. Concentrated sulfuric acid is one of the wildest. Another way is to use dryed salts such as CaCl2, MgSO4, CuSO4 or Na2SO4. Most of these are cheap and easy to get but usually contain lots of water molecules and so you have to activate them yourself by strong heating.

As much as i know therre is no easy way to compute solubilities. You have to make your own experiments or look for manuals. If anyone knows that those data can be computed someway then i'd like to know more about it. It would be very usefull - so i get rid of some heavy books on my table.

No you can't simply put piece of wire. Main concern is that your electrode must have aproximately the same coeficent of theraml expansion than glass. Usually molybdenium wire is used ( if i remember it right ). Another way is to use strip of very thin metal foil. I have seen it on some xenon tubes that were used for lasers. Edit: If you have time to experiment you can try various available wires. ( for example those you get when you break ordinary tungsten lamp ) If glass will not crack after cooling down and wire sits firmly in place then this is probably ok.

It seems that you are right. At once after the melting there was some small bubbling. So it was oxygen. I thought it is H2O because i was not sure how dry may KNO3 is.

I took 3g of KNO3 and put it onto small stainless steel bowl. I expected that if i heat it it will decompose to K2O and some nitric oxides by rather wild bubbling. KNO3 melted almost instantly and when i continued heating KNO3 was still liquid and completely quiet. Just stainless steel had some reddish glow that was clearly visible through liquid nitrate. How to decompose KNO3 not going to still higher temperatures? I want to make some KOH from it. ( Just experimenting on various uses of nitrates. )

One of rather good electrolytes that can be used to make H2 and O2 is solution of NaOH. It's strong point is that amount of NaOH will never decrease due to secundary reactions that take place. You only have to add water, no mater how much you use your electrolyser. If you use sulphates or H2SO4 as electrolyte it is all easy as long as current is low (maybe less than 5 ampers), on high currents sulphate ions start to decompose and you get some SO2 or SO3 too. ( I have forgoten what exactly happens. )