raivo

Jdurgs calculations on NaF had presumption that you will use 1.2V. You probably will use much higher and this means you get some hydrofloric acid near positive electrode. This will corrode your device quickly (even glass) and is too dangerous chemical do deal with if you just want to make H2 and O2. NaOH is surely better. I have always used stainless steel electrodes but i know of people who used common iron with satisfactory results. Graphite from pencils is of too bad quality. Its usable for very short demo not for any kind of production. Battery graphite is better but it too will disintegerate soon. Make electrode surface as big as you can and place them as near to each other as possible ( you still have to be sure that H2 and O2 will never mix with each other). If you still do not get required current with 12V supply then its best to rebuild your electrolyser. Otherwise you will not cope with heating problems. I suggest you to do some testing before you start to build anything. You can find answers to your questions if you just test how things are. Do some electrolysis on small flask with NaOH solution (or other electrolytes you have) also test different electrode materials and decide yourself what is most effective and reliable in your case. Its good to borrow ampermeter from somewhere otherwise you do not know what current you got. PC power supplys are usually able to supply 4 ... 8 A @ 12V and 10 ... 20A @ 5V. Current will change during electrolysis at constant voltage ( usually will increase by heating ).

Older PC power supplies tend to be completely foolproof. They switch itself off if short circuit is detected and after removing 220V for some time they are ready for work again. So its good choice. You cant use as much current as you my want because most of electrical energy will go for heating and you will end up with boiler instead of electrolyser. There is much less heating if you can get required currents using small voltages. Industrial electrolysers use most often 4...5V. Best electrolyte for making H2 and O2 is NaOH solution. It conducts very well and you can use stainless steel as electrodes. No dissolving of electrdes and no byproducts are formed. If you want just H2 its easyer to make it chemically by puting some Al foil to NaOH solution. You have to be very cautious though. If your hydrogen gets contaminated with remarkable quantities of oxygen you have got explosive thats very unstable and any microscopic arc somewhere in your electrolyser will detonate it immediately.

I suppose we do not get acid ( or alkali ) burns because we are rather quick to remove acid from skin. Minute or two are just not enough do decompose skin. Half on hour may be completely different story.

Brown color is at least partially due of MnO2. Its true that chemicals on the skin do not cause always burns. I have similar experience with conc H2SO4. No burn but fingers got nastily oily and started to itch. It took lot of washing with soda and water to reach the point where my finger did not change water ph any more Saing that its still very important to be cautious with chemicals because contact with skin turns painfull even in case of such friendly stuff as NaCl or KNO3 if you have small cuts on your skin (i have experienced this) - and you will get permanent damage if you happen to touch your eyes with hands in such condition!

NaCl + HCl will not work. Potassium permanganate or potassium dichromate + HCl can be used do make chlorine.

Sulfuric acid will not dissolve glass but only high quality heat resistant glass is safe to use because other glassware may break by heating.

I have book that says it sublimes. Maybe this is the same as with NH4Cl: Ge will immediately oxidise at 700C if it meets oxygen atoms. If it recombines to the same kind of oxide we are both right, but i am unable to test this.

Yes, AlCl does not exist. (it was meant AlCl3) But GeO exists. Its black powder, sublimes at aproximately 700C.

I agree with jdurg here.

Iodine is most common. Another is that famous NH4Cl. Some more are NH4Br, NH4I, AlCl (only if its not hydrated), GeO. Almost every substance can sublime if heated in vacuum.

NH4Cl surely decomposes and recombines although this process is so similar to sublimation that its not always important to know what exactly happens. Decomposition of NH4Cl can even be tested in simple experiment: Heat small amount of NH4Cl to temp at which white smoke rises and put some piece of oxidised copper so that it gets in contact with that smoke. Copper immediatelly loses its oxide because HCl reacts with it. This is why NH4Cl is sometimes used at soldering work. All ammonia salts decompose at rather low temperatures and i know of none that can be in liquid state under atmospheric pressure.

Quarks need not be smaller than protons or neutrons. Particles do not have clear borders as things in our world do. They act more like irregularitis in energy field. Question what they are made of may also became senseless in some point. Quantum mechanics and especially anything that follows it is mostly just bunch of equations that gives us right numerical results but is unable to say how things look like.

H2SO4 will not evaporate below 200C (or even more). You have to heat over 100C, boiling water bath is not hot enough. Anhydride dissolves so well that you even can not put tube into water because liquid will instantly rise up by tube into your boiling flask. Experiment with few milliliters in test tube and ONLY if you get everything working go to greater amounts.

I said "dry nitrate"! You just have to pour so much H2SO4 that all nitrate is wet and you have to watch it stays wet during the process. Otherwise you may decompose it by heating.

May well be true but if you do not inhale it in remarkably quantities nothing will happen. Nitric anhydride is not that mysterious substance. Anyone who deals with nitric acid (like some artist for example) will inhale it occassionally. Nitirc acid, even diluted fumes, that gas. To make nitric acid safely you need good fume hood or have to synthesise it outside. You still have to be extra cautious not to inhale any fumes. Amount of H2SO4 has to be such that there would never be any dry nitrate. Otherwise you may decompose nitrate by heating and if you are especially unluky that process may decompose you.

[math]\ce{H2SO4 + KNO3 -> KHSO4 + HNO3}[/math]

Battery acids are usually 30...40% sulfuric acid. So you need it 2.5...3 times of the amount of 100% acid. Zinc sulfate is well soluble in water. You can dissolve all "ice" if you add enough water. Its probably better not to mix calcium chloride and zinc sulfate. If you mix any sulfate with calcium salt then replacement reaction takes place. In your case you made calcium sulfate ( gypsum ) and zinc chloride. Not problem, expect that gypsum is not soluble in water and will settle into bottom of vessel. Zinc, now as chloride, will stay in solution and is probably still available for plants. I do not know much about fertilisers but it seems that sulfates are usually prefered to chlorides. Maybe a lot of chlorides is not good for soils. Before applying your selfmade fertiliser to soils its good to test its ph to be sure all acid has been reacted (although in case of zinc this probably is not a problem).

I too think now that YT is right. Or maybe someone just exercised basic glasswork. You still can use this for gas collecting although longer center part would be better.

This may be true but there are also such solvents as DMF, DMSO, pyridine and many others that are polar some way but not very reactive with alkali metals. This property has everyday uses in lithium batteris. Sodium battery can probably be done also but it would be too dangerous to be practical.

Maybe for collecting gas from test tube to capsized flask that floats on water tank.

Maybe this is not the increase in burn rate that makes black powder to explode but just that everything will explode violently if pressure of gases inside has reached critical limit. That may be very slow reaction where gases build up with months but if pressure in container gets too high, sudden explosion will result. One more reason may be that initial pressure wave makes another parts of powder to ignite even before direct burning reaches them.

To dissolve 55 pounds of zinc you need aproximately 82 pounds of 100% sulfuric acid. You have to use some excess of zinc to be sure all acid will be reacted otherwise you will acidify your soil.

I have one organic chemistry book where making chloroform by distilling mix of calcium hypochlorite and acetone is described. It seems to be quite straightforward. They put mix of calcium hypochlorite and water into flask and added acetone by small amounts. Output was 60% or 30g when using 200g of hypochlorite and 25g acetone.

I did not use organic solvents to de-grease coin but i scraped it to be sure at least some surface is completely clean. So they have added something to that Ni to make it more inert? I never have tried to dissolve pure Ni but various chromium nickel alloys i have got are easily soluble in those acids.

I tryed to dissolve nickel plating on coin. So i put it to 40% sulfuric acid. Nothing happened. After that i heated acid in water path to 80 C and waited. Still nothing happened. Then i placed coin into 23% nitric acid. Nothing. 20% hydrochloric acid even when heated made only slightest bubbling and no remarkable harm to nikcel surface. So i put a drop of 85% sulfuric acid onto coin surface - nothing but when i heated the coin, just before decomposition of sulfuric acid reaction started and almost instantly nicel plating disapeared under drop of sulfuric acid. Is nickel trully so unreactive or maybe that plating was some especially inert alloy? Your thoughts?