I am whittling away pieces of mild steel using direct current in 1% NaCl solution. The by-product is hydrogen gas.
According to my calculations 1 Amp over 40 minutes should produce only about
0.28 litres of hydrogen gas. The emphasis here is *my calculations*. Can anyone here confirm that this is correct?Michael Koblic, Campbell River, BC
Could post on sci.chemistry, and get a long lecture and wrong answer from fuknUncle Al....
Amps are coulombs per sec, and are some fraction of a mole, mebbe 10^-5. 1 mole of gas at STP occupies 22.4 liters. If the stoichiometry of the reaction itself is correct (not sure what that reaction is, other than the straight hydrolysis of water), everything should come out as some ratio.
You should proly be whittling away not by just driving Fe ions into solution, but by actually plating them onto a sizable (area-wise) negative electrode. Otherwise Le Chatelier rapidly slows the reaction.
Offhand, 1 amp over 40 minutes is 2,600 seconds or about 1/40 of a mole, if the reaction is 1 to 1, for H2 gas -- which it proly isn't. So the max you would get is about 1/2 liter, and you calc'd out .28 liters (about 1/4), which is proly in the ballpark, reflecting a factor of 2 in the overall stoichiometry.
You gonna compress the H2 for a hydrogen car??.
Not correct. There's a lot more going on than you might think to affect the yield.
Could post on sci.chemistry, and get a long lecture and wrong answer from fuknUncle Al....
Amps are coulombs per sec, and are some fraction of a mole, mebbe 10^-5. 1 mole of gas at STP occupies 22.4 liters. If the stoichiometry of the reaction itself is correct (not sure what that reaction is, other than the straight hydrolysis of water), everything should come out as some ratio.
You should proly be whittling away not by just driving Fe ions into solution, but by actually plating them onto a sizable (area-wise) negative electrode. Otherwise Le Chatelier rapidly slows the reaction.
Offhand, 1 amp over 40 minutes is 2,600 seconds or about 1/40 of a mole, if the reaction is 1 to 1, for H2 gas -- which it proly isn't. So the max you would get is about 1/2 liter, and you calc'd out .28 liters (about 1/4), which is proly in the ballpark, reflecting a factor of 2 in the overall stoichiometry.
You gonna compress the H2 for a hydrogen car??.
OK, do you know the correct answer?
Michael Koblic, Campbell River, BC
You crash land amid fearful Transylvanian villagers with flaming torches. Ne strelyayte!
This mentions the oxidation and reduction of iron as competing reactions:
That's -Doctor- Kinch. He worked so hard...
-- An appeaser is one who feeds a crocodile, hoping it will eat him last. -- Sir Winston Churchill
ROTFLMAO! Consider the source...
You crash land amid fearful Transylvanian villagers with flaming torches. Ne strelyayte!
-------------------------------------------------------------------------------- You hope to run into bilingual Transylvanian villagers? "Nu trage!" would be my choice. How correct a a choice, well, no doubt one would find in the next few seconds...
Ah, well, airship not a good choice then. Who knew! I did not trust them new-fangled things anyway.
-- Michael Koblic, Campbell River, BC
BTW do you see the formatting of this reply as seriously screwed up? I shall have to get that formatting program again - what was its name? Another victory for Microsoft! Even the signature is not coming out right now.
This mentions the oxidation and reduction of iron as competing reactions:
-------------------------------------------------------------------------------- That is consistent with the info in a big thick book I bought for $2 in a garage sale. I think the salient points are:
1) The process chews up iron to my satisfaction if I can stop the foul-biting 2) The by-products are as predicted and benign 3) The quantity of H2 will not fill a decent-size airship. Or blow the house up.-- Michael Koblic, Campbell River, BC
This is how your sig file needs to look, including the blank space after the two dashes:
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Michael did anyone mention the chorine given off as being toxic? I got a lungful as a kid doing the same thing you are, coughed my arse off for an hour, then slept for two. I survived!
The hydrogen also did a good job of cleaning the rust off the inside of our wood fired hot water heater when it exploded.
The big difference is I guess that I was collecting the gas evolved where you I understand are letting it dissipate.
Not exactly _the_ by-product. More, _a_ by-product. HCl is also a gas. Keep it outdoors.
I'd do this in vinegar/water, or oxalic acid/water, instead; the ferrous oxalate is water soluble, which should speed the process.
What actually happens, in wet-chemistry situations like this, is known to be a challenging field of study.
This is how your sig file needs to look, including the blank space after the two dashes:
You are still missing the space after the double dashes. That prevents most newsreaders from automatically deleting a sig file when replying.
Michael did anyone mention the chorine given off as being toxic? I got a lungful as a kid doing the same thing you are, coughed my arse off for an hour, then slept for two. I survived!
The hydrogen also did a good job of cleaning the rust off the inside of our wood fired hot water heater when it exploded.
The big difference is I guess that I was collecting the gas evolved where you I understand are letting it dissipate.
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A valid point.
I looked into the chlorine production and this is what I found:
1) There is chlorine produced at anode if the electrodes are inert. 2) I am not sure how the situation changes with one of the electrodes (iron) being consumed. As far as I can determine the iron ends up as a precipitate of Fe(OH)x. This pulls out the OH- out of the solution. Does Cl- stay in the solution to balance the Na+? 3) I watched some interesting videos of aequous NaCl electrolyzed with graphite electrode. It was quite aparent that there was more H2 being produced than Cl2. Looking into this further it seems that some of the Cl is dissolves to form ClO-. 4) Thus if I produce 0.28 l of hydrogen duirng the course of the process (and that is assuming 100% efficiency) there should be even less chlorine. The rate of production is about 7 ml per minute. That should dissipate in a well-ventilated area. 5) In none of the instances was I able to detect presence of chlorine by colour or smell.Things get more interesting if one acidifies the solution. It definitely limits the production of the Fe(OH) precipitate. So what happens to the iron and how it affects the chlorine production is a matter of guessing on my part.
One should probably investigate this fully. I shall produce a modified set up and try and collect the gases.
The best reference for this process I could find:
-- Michael Koblic, Campbell River, BC
Not exactly _the_ by-product. More, _a_ by-product. HCl is also a gas. Keep it outdoors.
I'd do this in vinegar/water, or oxalic acid/water, instead; the ferrous oxalate is water soluble, which should speed the process.
What actually happens, in wet-chemistry situations like this, is known to be a challenging field of study.
--------------------------------------------------------------------------------
Thanks.
Now I understand where the iron goes whan you add vinegar - iron acetate, of course!
I was not entirely sure how HCl would be produced by electrolysis of neutral aqueous NaCl solution.
As it happens I did try acidifying with HCl (in the form of a toilet cleaner) today. Not a good idea! Foam++, HCl in the air (even a 10cc in water is bad enough to breathe for 40 minutes) and in the end it obviously got used up as the green and red sludge re-appeared.
What does acidification of the NaCl solution do for the chlorine production? I did not smell any when I was using the vinegar.
The whole thing raises the question if there is a better electrolyte for this process than NaCl but that is all the references I could find.
-- Michael Koblic, Campbell River, BC
...
All this discussion about the chemistry has been interesting enough, but just what are you trying to do here? Make a part? Or just screwing around, er .... experimenting? A home-shop electrochemical process might be kind of neat.
Bob
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