Sciencemadness Discussion Board - Calcium Carbide CaC2 - Acquisition, Uses and Synthesis

Calcium Carbide CaC2 - Acquisition, Uses and Synthesis

kazaa81 - 30-8-2004 at 13:43

Hallo to all,

I'm looking for CaC2 in Italy, but I haven't find anything. Is it today used?
I don't know, because acetylene lamps aren't used today.
Where and under what name I can buy it (except scientifical suppliers)?

Thanx for help.

[Edited on 3-9-2004 by chemoleo]

bobo451 - 30-8-2004 at 15:05

CaC2 is used in the steel industry for desulfurization. I'm not sure on availibility. You might check ebay. I know there was some for sale in the past. I haven't checked in a while.

Hang-Man - 30-8-2004 at 16:32

United Nuclear sells it, but as usual at shitty prices.

Anyone know of a way to make it that doesn't involve 2000C and an arc funace?

JohnWW - 1-9-2004 at 15:48

If you have powdered or granulated Ca metal - which has been offered elsewhere on this forum, usually made by electrolysis of a fused Ca halide salt - and powdered carbon (e.g. lampblack/soot, graphite, coke, anthracite coal), you can stoichiometrically mix them together in a steel pressure vessel in the absence of air (preferably under argon), and heat the mixture to the melting-point of Ca, 810ºC (but below its boiling point, 1,200ºC), you would get the carbide, CaC2, which is an ionic acetylide. The reaction is fairly exothermic, so no further heating should be required to keep the Ca molten except when it is near completion.

It reacts rapidly with water to produce C2H2 and Ca(OH)2. C2H2 is used in the gas cutting of steel, and (at lower heat) gas welding of bronzes and brasses, due to its very hot flame.

It has other uses, in industrial organic syntheses, e.g. ethylene glycol, and especially to make, by partial catalytic hydrogenation, C2H4, which is widely polymerized to make polyethylene and other plastics. However, most ethylene now comes as a byproduct of catalytic cracking in petroleum refining.

Acetylene adds water readily in the presence of H2SO4 and Hg++ ions as catalysts, producing vinyl alcohol which can be polymerized to polyvinyl alcohol (used as PVA glue), although the alcohol tends to rearrange to acetaldehyde.

chemoleo - 1-9-2004 at 16:14

As far as I know, there is no easy way.
However, it is entirely possible to make it with an arc furnace.... that is, because I made it myself!
Quite simple really, miix the correct amounts of CaO and C, and subject them right into the arc.
You willl get chunks of solid stuff - and these chunks, when put into water, produce a flammable gas, that burn with a small pop and a yellow flame.
If you want I can tell u more.
I did this a long time ago, and I always meant to take pictures (this was before the digital age) just to document the process. It seriously isnt that hard. I got about 2 g worth, in a matter of 15 seconds (I stopped, or got stopped because of the power failing.... seemed like I took more than 16 Amp/230 V out of the power grid. Basically, the automatic power fuse shut down, for the whole house. and 230V * 16Amp = ~ 4kW is about the max it seems.

Organikum - 1-9-2004 at 16:32

Shops which sell stuff for cave-exploring sell also calcium carbide. The cave explorers still use acetylene lamps for several reasons.
Cave exploring has become a widespread hobby in the last years, it shouldnt be so hard to find a supplier in Italy - Google.

Here were live CaC2 is sold OTC in every Drugstore - dont even know what for exactly.

rift valley - 1-9-2004 at 18:51

http://www.calcium-carbide.com/

not much help to you but if your from the states you can order from there. I bought a pound and it is fun to play around with in small quantities

JohnWW - 2-9-2004 at 11:11

Starting from CaO (burnt lime) mixed with powered carbon is rather less efficient energetically than using electrolytically-produced Ca metal with C, because of the much higher temperature needed (CaO melts at 2,570ºC, above the melting-point of steel), it may be an endothermic reaction because of the much higher enthalpy of formation of CaO compared to that of CaC2, and the CO2 gas produced in the closed container which adds to the pressure. But, if you have plenty of cheap anthracite coal, and a refractory-lined furnace, it may not matter.

John W.

THIS CAN'T BE TRUE!?!?

chemoleo - 2-9-2004 at 19:20

Well maybe there is an easy way to the synthesis of CaC2!!!

Check this US patent 4,301,133

To quote the method:

Quote:

Into a stainless steel cylinder is placed a uniformly blended mixture of 56 grams of calcium oxide (60 mesh) and charcoal (60 mesh). To the mixture is added 25 grams of pyrophosphoric acid with stirring to form a pasty mass which is then compressed with a rod piston adapted to fit the inside of the reaction cylinder.

The exothermix reaction is allowed to run its course and after cooling (about 15-20 minutes) the piston is removed from the cylinder together with the hard cake of calcium carbide.

The calcium carbide so produced, after crushing to a uniform particle size of 0.25 inch mesh and placing in water, reacts to generate an acetylene base fuel gas.

Now, what is going on here?
The pyrophoric acid reacts with the CaO, to form the phosphate and water... and how does this WATER not interfere with the putative resultant CaC2?
What's the mechanism of this?
Or does this guy just produce methanes and such?
Very strange, the whole thing... ideas?

Wow, if I don't misread this or something, and if this is truly possible - then I know my next project!

Two neatly-fitting steel parts, and a bench press --> bingo! THat is, if the pressure required isn't super high... which is what I suspect. THis guy shamelessly didn't bother remarking on the pressure required

[Edited on 3-9-2004 by chemoleo]

JohnWW - 2-9-2004 at 19:32

That patent 4,301,133 does not sound plausible - the patentor must have fooled the US Patent Office somehow, especially as no (at least initial) heating is specified. Even allowing for the fact that the pyrophosphoric acid would take up the water produced to become phosphoric acid, this would not stop the immediate acid hydrolysis of any CaC2 produced to Ca3(PO4)2 and acetylene. And as I said before, the reaction is unlikely to be exothermic.

John W.

BromicAcid - 2-9-2004 at 20:30

Hummm, you missed the key word in the patent, 'Compressed' the patent author could have compressed this mix with a pressure that could have equivalently have made diamonds. This could have resulted in a branching type reaction where new bonds are formed by pressure alone.

Besides, there may have been no fooling involved, you don't have to prove a reaction works to patent it, there are plenty out there that just may have showed some possibility of working that some scientist was quick to patent out of worry before extensive testing proved them wrong.

Edit:

Quote:

It thus will be seen that the objects and advantages of this invention have been fully and effectively achieved. It will be realized, however, that the foregoing specific embodiments have been disclosed only for the purpose of illustrating the principles of this invention and are susceptible of modification without departing from such principles. Accordingly, the invention includes all embodiments encompassed within the spirit and scope of the following claims.

They always get you with that don't they, saying that this might not be how we do it, this is just enough information so that we can sue you if you attempt

Is it 56 g of CaO and 56 g of charcoal of is it 56g total? I was trying to figure out the molar ratios and 56 g is about the atomic weight of 1 mol of CaO which could be coincidental. Still the description is odd in that the rection mixture immediately starts to exotherm with the production of water vapor, why would you immediately try to seal it if the water vapor was being trapped within?

[Edited on 9/3/2004 by BromicAcid]

Thats how it looks like:

Organikum - 3-9-2004 at 03:29

BromicAcid - 14-3-2005 at 19:26

Some on aquisition, some on preparation, but nothing in this thread on uses really. I recently came to own 500 g or so of calcium carbide and I found that my intentions to make dichloroethane may have been mislead and that it is most likely unsuitable for this purpose. As such I need something to do with it. No energetics though. There is a thread around here about reacting it with alcohols but it really doesn't have any conclusion. Any suggestions would be honestly appreciated.

chemoleo - 14-3-2005 at 19:55

Well, I think I mentioned it before, any acid stronger (in theory) than acetylene should produce the respective Ca-salt and acetylene.
Acetylene has a pKa of 26, and NH3 36. So acetylene is a stronger acid than ammonia. But ethanol has a pK of 16, butanol is at 19, primary amides RCONH2 at 17, etc, so this should react with the CaC2, producing the respective derivatives.
So yes, this seems a route to calcium ethanolate! Make sure you use 100% EtOH though.

Here's a good summary of pKa's of various (in)org. compounds, this should give us some ideas as to what can be done... in theory

Acetylene gas can be used to prepare alkynes, too; acetylene reacts with NaNH2 to form HCCNa, this can react onwards with i.e. 1 bromo propane to form NaBr and 1-butyne.

This can of course be reacted onwards, i.e. again with sodium amide, to form the Na derivative, which can be reacted with any arbitrary bromo alkane. Looks like with NaNH2, synthesis of simple alkynes is easy.
I don't know however how this synth route fares with substituted bromo derivatives. This route only works with primary bromo derivatives, secondary/teritiary ones undergo elimination.

[Edited on 15-3-2005 by chemoleo]

BromicAcid - 14-3-2005 at 20:54

Maybe crush it up some more and pull dried air though it to make cyanimide. There shouldn't be a reaction with oxygen would there, just the nitrogen?

home arc furnace

S.C. Wack - 14-3-2005 at 22:32

I think the O has to be taken out.

Brauer's:
A large porcelain crucible, at least 80 mm. in diameter on top
and 60 mm. high, is filled with a well-blended, dry mixture of
equal parts of quicklime and wood charcoal to a level 10 cm. below
the rim. The ingredients are not too finely powdered to prevent
elutriation losses during later gas evolution. The crucible is
placed on top of a brick. Two carbon rods (carbon welding
electrodes, or rods made of electrolytic graphite), at least 15
mm. in diameter and 200 mm. long, are tapered to a point at
their lower ends, while slotted (and thus flexible) brass caps are
affixed on their upper ends. Each cap has a clamp screw, which
serves as an electric terminal. A horizontal hole is drilled through
each carbon rod and cap combination, and a 1-2 mm. connective
copper wire is fitted snugly into the hole and bent back at both
ends so that the cap is securely attached to the electrode. The
electrodes are attached to a stand in such a way that they reach
down to the center of the crucible, and their points are about 10
mm. apart. The asbestos insulated clamps connecting the electrodes
to the stand are attached just below the brass caps. The lime-charcoal
mixture is piled up in the center of the crucible and the
latter is then covered with an asbestos sheet. Insulated copper
wires (cross section 16 mm.) connect the electrodes to the power
supply. The electrodes are in series with 0-50 amp. ammeter, a
40 amp. rheostat (6 ohms at 220 v., 3 ohms with a line voltage of
110 v.) and a double-pole knife switch. Where a suitable rectifier
is available the use of direct current is preferred since a D. C.
arc is far smoother than an A.C. arc. The potential across the
electrodes is measured with a voltmeter.

The current is switched on with the rheostat set at maximum.
It takes some time before the electric arc is initiated. The current
is then set at 30-40 amp. The voltmeter should register a
potential of 50-70 v. If the reading is much higher, the carbons
are too far apart (and vice versa). The current must be shut off
before any adjustment is made. When the operation is properly
conducted, long tongues of burning CO escape from the crucible
together with occasional puffs of dust from the charge. The current
is shut off after 5-10 min. and the crucible is left to cool. A
few grams of sintered or lump calcium carbide will be found under
the electrode ends.

Mellor's:

BromicAcid - 15-3-2005 at 15:43

I tried reacting a test tube full of methanol with calcium carbide today. If there was a reaction it was incredibly slow, there were some tiny clinging bubbles on the surface of the pieces I put in there, but they didn't grow and I suspect there were just adhering there due to the rough surface texture. The reactants were cold but still nothing noticeable. Going to let it sit overnight with a watch glass on top and check tommorow to see if the piece of calcium carbide is anywhere near dissolved.

chemoleo - 15-3-2005 at 17:28

Just as a suggestion, it does sound like a case of the product not being soluble in the reactant (methanol).
I wonder what happens if you actually crush the CaC2, and THEN react it with methanol while stirring continuously?
Alternatively, maybe we ought to look into solvents in which the PRODUCT is soluble in. I.e. Ca-methanoate, is it soluble in methanol? if not, we know why it doesnt dissolve (and therefore inhibits the reaction despite favorable pKas.).
So using other solvents might solve the problem.

PS good to see someone is trying at least!

[Edited on 16-3-2005 by chemoleo]

BromicAcid - 15-3-2005 at 17:41

Looking up calcium methoxide online I found no physical data except that when it is purchased it still has a high methonol precentage, maybe if it toally dries out it decomposes or maybe it holds it somehow. Maybe it's one of those many "Thermodynamically favorable but Kenetically Slow reactions". I'll have to just throw CaC2 at everything I have to see how it reacts, isopropyl alcohol, chloroform, phenol (which should definatley react) and other things.

BromicAcid - 16-3-2005 at 19:33

The calcium carbide I put into the methanol has crumbled to dust. There is a white powder in the bottom of the test tube. It was loosely covered with a watch glass to allow any acetylene generated to escape. There is still a very small piece of calcium carbide at the bottom but mostly it turned to the dust. Water could have gotten in, but for that quantity to have come in with the watch glass in place seems a little unlikely along with the constant vapor pressure exterted by the methanol vapor. Next step, strain it and heat it, if it is calcium methoxide I would think that it would decompose quickly at heat, or maybe attempt to react with water.

BromicAcid - 19-3-2005 at 09:41

It took roughly 4 days for the ~1g piece of calcium carbide in 7 ml of methanol to turn to a white powder. I decided that there was a simple way to test if there was caclium ions in solution and a hard way. I took a few drops of water and added them. Immediately a precipiate of white powder (calcium hydroxide I would assum) another drop, more white powder, another, more powder, this layer of white powder I created settling on top of the layer beneath it, showing they look somewhat different. The test tube heated slightly. Not 100% conclusive but it shows that there was atleast some calcium in solution and it wasn't in the form of hydroxide to begin with.

chemoleo - 19-3-2005 at 09:55

Shouldn't dry calcium methoxide burn?
I guess the fact it's turned into dust suggests that it is insoluble, and thus makes the reaction slow (albeit it being a favourable one).
Anyway, to test for the methanol, I guess you could take the dry powder, add some boric acid to it, and a bit of dil. H2SO4. THe resulting boric acid methyl ester should burn green.

CaC2 problems

12AX7 - 3-7-2005 at 05:02

Ok so I weighed out 130 grams +8 mesh hardwood charcoal and 200g +8 mesh limestone (hrm... I forgot to account for the CO3...doh, excess of C), toasted it a bit with some gouging rods and 80 amperes, obtaining some fused lumps with a pretty high melting point (not as high as CaO; definetly a different material). So I let the bits cool, crushed and added to water. And. No bubbles. HCl doesn't even do anything.

Too much SiO2 in my rock or something? (It's only Wisconsin yellow limestone/dolomite.)

Hrm, lesse... CaCO3 + 4C = CaC2 + 3CO, so I should've used 270, not 200, grams of limestone. Oh well, it's not like it forms a higher carbide (though C3(-2) is known), even if it did, it would still hydrolyze...

Tim

garage chemist - 24-8-2005 at 11:24

I am currently trying to dry Ethanol (94 - 96%) with Calcium carbide. I added a few spoons of the small CaC2 rocks to 250ml Ethanol.
There is a bit of bubbling, the rocks seem to get smaller and lots of white/grey powder is produced.
Does anyone know if CaC2 reacts with absolute Ethanol?

Another problem is the produced acetylene gas. I am trying to make some 99% ethanol for production of Chloral hydrate, and dissolved acetylene would be very inconvenient here due to formation of tetrachloroethane, a very toxic and carcinogenic compound.

Will a distillation get rid of the dissolved acetylene?

IrC - 24-8-2005 at 12:34

I think the patent 4,301,133 has to be right. It would answer a question I always had, i.e. why does the gas have a garlic odor created by a phosphine impurity in the gas. This is very common in every batch of carbide I have ever had. Where else could the phosphine impurity be coming from other than the fact that it is likely most commercial carbide is made by this patent?

I have 2 pounds of carbide I bought for 10 bucks from a guy on ebay in canada, and the Acetylene also has the phosphine odor, telling me that they also must use this same process to make it.

[Edited on 24-8-2005 by IrC]

garage chemist - 24-8-2005 at 14:29

The commercial carbide is not prepared by the pyrophosphoric acid method, otherwise it would be more expensive (phosphoric acid isn't that cheap since it needs white phosphorus as a precursor).

The garlic odor of the carbide results from PH3, thats clear, but the origin of the calcium phosphide is from impurities in the used calcium oxide. It contains small amounts of phosphorite or apatite which get reduced to phosphide in the arc furnace.

In the arc furnaces, the CaC2 leaves the furnace in a molten state at over 2000°C.
Imagine how bright that must be...

IrC - 24-8-2005 at 15:09

I have CaO at 1,100 C about every other day, and it is bright with #6 welding glasses. I wish I had a kiln that would do over 2,000 C. So that makes sense but then I wonder how the PH3 stays in there at those temperatures. It would seem it would all be up in smoke before the stuff cooled down. Or maybe it forms while cooling but then I don't know where it would get the hydrogen from. Just doesn't seem that stuff would still be in there while that hot.

12AX7 - 24-8-2005 at 15:38

Well uh.. it's kind of anhydrous at that temperature, so it tends to stay bound as phosphide (reduced from phosphate by carbon, just as Na2SO4 + 4C = 4CO + Na2S).

1100C, pffbt that's nothing, I was at that temp just the other day inside some kaowool. Calcined some lime while I was at it, too.

Now blinding white hot...that's when you get into molten iron and steel.

Tim

IrC - 24-8-2005 at 17:32

I use oxy/gas (various) for even higher temperatures but I was referring to the inside of my electric kiln. 2,200 F may not sound like much but it is when you have several pounds of material inside several square feet of firebrick all at this temperature. But I understand now, the hydrogen to make PH3 is coming from the water when you put CaC2 in H2O. Don't know why I didn't think of that earlier. So there are a few more reactions going on in there than I realized.

12AX7 - 24-8-2005 at 18:04

Quote:

Originally posted by IrC
I use oxy/gas (various) for even higher temperatures but I was referring to the inside of my electric kiln. 2,200 F may not sound like much but it is when you have several pounds of material inside several square feet of firebrick all at this temperature.

Ah, not a bad size for ameteur work. But...still..

I'll have to show pics here of the 3.2 cubic foot gas kiln I'm building.

H2S, PH3, CH4 and etc. also grace the presence of my nose when breaking up (salt) slag left from melting aluminum or magnesium.

Tim

jimmyboy - 25-8-2005 at 09:34

calcium carbide simply doesnt have any demand anymore - why its pretty uncommon to find it - i would still like some to mess with though

An excellent detailed writeup on making it a few grams at a time can be found in Brauer (Inorganic Prep) - i also remember having a pdf that detailed using carbon rods and a high wattage electric heater as a DC source to provide enough amperage - anyone done all this already? any success stories?

IrC - 25-8-2005 at 11:52

I would think a variable core Lincoln arc welder would be perfect for that. 12AX7, how hot does a gas kiln get, and what temperature can the fire brick kilns are made of take? I still don't know how hot is safe in my kiln, at 2,400 F my meter pegs, light was shining through the brick clear to the outside. Scarey looking when it is sitting on the floor inside the house.

12AX7 - 25-8-2005 at 15:22

Depends on the firebrick...some day I want to fire some high alumina insulating bricks and make a cone 30 kiln. Yes, that's hot enough to pretty near melt platinum, and titanium if it didn't burn like hell.

Bricks with high flux content like calcium and potassium might melt lower than 2100F, or lower.

Tim

garage chemist - 26-8-2005 at 04:03

I can still buy CaC2 OTC in most home/garden stores as "Wühlmausgas", as a means of getting rid of moles and "Wühlmäuse" (don't know the english name for them).

It is sold in rather fine granulated form, about 4-7 mm grain size.
The normal means of use is to throw a spoon of it into a mole nest and close it. The humidity of the soil causes the hydrolysis of the carbide with the evolution of PH3 stink, which should make the moles move out of the garden.
It is sold in metal cans of 250g or 500g content. On the label, it says "contains 800g/kg CaC2", which is just technical grade carbide.

However, you can't just walk into the store and buy it. It is locked in a safe cabinet and can only be got on request for the specific product.

I don't know if you can get it outside of germany, at least I've never heard of it being available in the US.

If there's interest, I could post a picture of the product and label.

woelen - 26-8-2005 at 10:47

In certain parts of the Netherlands you can buy it at kilogram quantities just before new year's eve. It is used as an alternative for fireworks. It is called 'Carbid' and it is technical quality, containing quite some phosphide.

For those who can't obtain CaC2

stygian - 21-11-2005 at 15:47

This may be of interest to those wanting/needing acetylene, but cant obtain CaC2 for some reason (it's also cool, just found it digging around for info on phorone).

Electrolysis of Salts of unsaturated organic acids leads to a combination of acetylene, methylacetylene, propadiene, CO, and CO2.

Source: http://jagor.srce.hr/ccacaa/CCA-PDF/cca2002/v75-n1/CCA_75_20...

[Edited on 21-11-2005 by stygian]

kazaa81 - 22-11-2005 at 12:04

Isn't that a Kolbe electrolysis?

stygian - 22-11-2005 at 13:57

Read the document. Kolbe theory says that unsaturated acids 'dont work' supposedly. The truth seems to be that they produce the unsaturated hydrocarbons mentioned. One such acid, crotonic (oxidize crotonal, made from acetaldehyde)

DeAdFX - 23-11-2005 at 16:59

Calcium carbide is used for fertilizers...

CaC2 + N2 = CaNCN

Calcium carbide reacts with nitrogen to produce calcium cyanamide(sp)...

neutrino - 23-11-2005 at 17:35

How would one then go about obtaining this carbide? I've only ever heard of the cyanamide sold for fertilizer.

DeAdFX - 23-11-2005 at 17:38

Quote:

Originally posted by neutrino
How would one then go about obtaining this carbide? I've only ever heard of the cyanamide sold for fertilizer.

To be honest I have no clue. It was a use for CaC2. You could try asking someone who works at a fertilizer plant for CaC2? Other than that no clue.

This reminds me in my schools chemical storage area I saw a container for CaC2. I don't remember any specifics of the container but if it is still there I wouldn't mind taking picturs of it.

chemoleo - 23-11-2005 at 18:48

What do you mean, 'this carbide'?
Calcium cyanamide is widely used. .. as a lawn fertiliser. If it's used here, it most certainly will be in the US... you just have to find it.
The reaction of CaC2 and N2 requires high temperatures (>700 deg C IIRC) to work however. Might be easier to just play with the fertiliser (one project that is, one day, on my to do list).

Anyway. Is someone going to try the purported route of C/CaO/pyrophosphric acid /pressure, as mentioned above?
Although unlikely to work, don't you think it's worth a try?

S.C. Wack - 23-11-2005 at 19:43

No, the cyanamide is not used as fertilizer over here. You would have seen mention of this if it was.

http://hazmap.nlm.nih.gov/cgi-bin/hazmap_generic?tbl=TblAgen...

BromicAcid - 23-11-2005 at 19:50

Over the last several years I have tried to find calcium cyanamide in my area with no sucess, as far as I can tell it is no longer avalible in the states except from scientific suppliers such as Spectrum (although you can never tell what smaller specialty shops may still be carrying). I was at one time tempted to even purchase it form here as I belive one can produce carbon tetrachloride from it.

Picric-A - 29-8-2008 at 15:38

Sorry to bring up and old post.
I used to be able to buy CaO in 25Kg sacks for around £6.
Now by garden centre has stopped selling them and i have had to buy Ca(OH)2 from a chemicals supplier at £3 for 1kg.
Can calcium hydroxide be used to make calcium carbide in an arc Furnace?

In response to the calcium cyanamide question, normally when one is making calcium carbide in a home built arc furnace fair amounts of calcium cyannamide are formed as hot carbide reacts with atmospheric nitrogen. Yet aother impurity in 'home made' CaC2

Formatik - 29-8-2008 at 23:15

Quote:

Originally posted by Picric-A
Sorry to bring up and old post.
I used to be able to buy CaO in 25Kg sacks for around £6.
Now by garden centre has stopped selling them and i have had to buy Ca(OH)2 from a chemicals supplier at £3 for 1kg.
Can calcium hydroxide be used to make calcium carbide in an arc Furnace?

CaCO3, CaO, Ca(OH)2 will all work. Though it would be better to dehydrate the Ca(OH)2 first, since it requires only moderate heat to dehydrate.

[Edited on 29-8-2008 by Schockwave]

Picric-A - 30-8-2008 at 02:21

If i didnt dehydrate it (heat to 550C) would this ruin the carbide produced?
Would you have to run the one with CaCO3 longer?
thanks,

12AX7 - 30-8-2008 at 05:26

Hydroxide and carbonate require additional heat and carbon to decompose.

Picric-A - 30-8-2008 at 08:55

cool thanks,

ScienceSquirrel - 30-8-2008 at 10:17

Calcium carbide comes up for sale on www.ebay.co.uk quite frequently.
I would just store a search and leave it for few months.
Cavers and collectors of antique carbide lamps use it.

Picric-A - 30-8-2008 at 14:10

but where is the fun in buying it?

ScienceSquirrel - 30-8-2008 at 17:29

Quote:

Originally posted by Picric-A
but where is the fun in buying it?

It is possible to make a few grams using a welder but it is quite laborious to make 50g.
I bought 500g for less than £10 including postage.
It is useful for making acetylene and acetylides.
A little goes a long way. A balloon filled with acetylene and air or 500mg of copper acetylide makes a spectacular bang.

Picric-A - 31-8-2008 at 03:06

fair point, where did you buy it from, if you dont mind me asking?
Has anyone tryed what Berthelot did, HHeat it in a glass tube to produce Benzene and toluene?
i was thinkning a long test tube with the end in water or oil,

YT2095 - 31-8-2008 at 04:10

I must be really boring.
I only use mine for its intended purpose, and although I understand the Chemistry and Mechanics behind it, to me they have a beauty all of their own and still fascinate me.

ScienceSquirrel - 31-8-2008 at 06:43

Quote:

Originally posted by Picric-A
fair point, where did you buy it from, if you dont mind me asking?
Has anyone tryed what Berthelot did, HHeat it in a glass tube to produce Benzene and toluene?
i was thinkning a long test tube with the end in water or oil,

I bought mine from an ebay trader that has ceased trading.
It is a question of looking around and having a bit of patience.

benzylchloride1 - 31-8-2008 at 10:03

Acetylene from Calcium carbide can be passed through a paste consistinf of mercuric sulphate and ammonium bisulfate to produce paracetaldehyde. Paracetaldehyde is a convienent source of acetaldehyde for chemical experiments. Reference: Systematic Organic Chemistry. This book gives a preparation of paracetaldehyde from acetylene.

My attempt to make Calcium Carbide

Picric-A - 31-8-2008 at 14:01

Unfortunatly i dont have a decent camera, and so i will have to make do with paint

I used my rather crappy arc furnace to do this. I took the carbon rods from a zinc chloride, D battery. at first when i cast te arc with them and stopped it they burnt. I presumed this to be oil or something in the rods.
The mix was decent lab grade calcium hydroxide and crushed BBQ charcoal. the mix was fairly fine but not near airfloat constituancy (sp?).
The furnace was simply a flowerpot with heavy concrete reinforcements.
My power source was a 130amp arc welder although i used 80 amps.
When i cast the arc on the mixture it blew the mix everywhere, spraying a white power... i presumed this was CaOH. There was no grey blobs left, only the white powder and i thought that the arc would radiate enough heat to reach the bottom of the pot but infact the mix on the bottom remained untouched.... it was only the surface that turned white.
Upon adding some of this white powder to water, no bubbling was observed so this powder was infact CaOH..

Any ideas on how i could improve? maybe a change of Furnace?
Thanks,
Picric-A

[Edited on 9-1-2008 by Polverone]

Arc.jpeg - 31kB

Magpie - 31-8-2008 at 15:26

Have read through this thread?:

http://sciencemadness.org/talk/viewthread.php?tid=2680&p...

Of special interest is the book by Stanfied that ignaro provides a link for called "The Electric Furnace."

Picric-A - 31-8-2008 at 16:03

Yes i have read that thread several times,
Last time i did this procedure everything worked out well, i just dont know why i didnt work this time...

12AX7 - 1-9-2008 at 05:57

Obviously the carbon is burning off the surface. You need to remove oxygen from the atmosphere and bury the electrodes in reaction stuff so it doesn't all blow away. Gas is produced so granular, rather than powdered, reactants is a plus!

Tim

Picric-A - 1-9-2008 at 10:14

Cool thanks for the help guys, when i get round to making a new furnace and doing the reaction again i will tell you how it goes!
Picric-A

watson.fawkes - 1-9-2008 at 12:55

Quote:

Originally posted by Magpie
Of special interest is the book by Stanfied that ignaro provides a link for called "The Electric Furnace."

archive.org has a DJVU version of that up now:The Electic Furnange. Yes, that's some bad, bad OCR happening.

Drying EtOH

tapira1 - 7-9-2008 at 08:16

Ethanol is best dried employing magnesium, via the magnesium ethoxide. Magnesium can be obtained from pen sharpeners or magnesium car wheels.

kilowatt - 27-11-2008 at 18:52

I wonder if CaC2 could be made by electrolysis of fused CaCl2 or CaCl2/CaO with a graphite or other carbon cathode. I intend to find out as soon as I get my equipment ready.

Picric-A - 27-11-2008 at 23:18

I guess by this method you are hoping the Calcium metal produced would react with the Carbon cathode.
Unfortunatly this method requires around 900 degrees, if not more, so it is unlikly you would get any.
Also how would you seperate the CaCl2 from the CaC2?

kilowatt - 28-11-2008 at 00:11

Well it is quite normal for such a cell to run at 900°C or more, and I do not believe CaC2 would be soluble in CaCl2. It beats the heck out of the 2000°C required for the traditional method. Quite frankly I do not see why the FFC Cambridge Process extractions of boron and silicon would not form the respective calcium boride or silicide similarly to this idea; if allowed to run until the oxide was depleted, it no doubt would, or perhaps it does anyway.

Sadly I was not able to experiment tonight on the matter. My steel cell crucible sprung a small leak along the welds, and I got a lot of fused CaCl2 poured out into the bottom my furnace, causing major problems. I cannot re-melt it and get it out because the bottom area of the furnace does not get that hot. The molten salt was quite solible with the furnace refractory as well so it is bonded. Just keeping the furnace from being destroyed now by atmospheric water absorption will be a huge challenge.

It's a heck of a mess. Dumping sodium carbonate in to react up the CaCl2 as it goes into solution would seem the best course of action at this point.

Picric-A - 28-11-2008 at 03:04

I agree CaC2 wouldnt be soluble in it but are you just going to scrape it out as it is formed?
I think it is more trouble than its worth, you might aswell take the calcium produced and heat that in a crucicible with Carbon...
But i still think an arc furnace is an easier method, i produced around a Kilogram, if not more, from my simple concrete lined arc furnace, powederd by my arc welder, with CaCO3 from the local chalk mine and Charcoal made on the bonfire, simple and cheap.

kilowatt - 28-11-2008 at 12:12

Extracting the actual calcium metal from an electrolytic cell like that is easier said than done. Calcium is soluble enough in the melt (3.9% molar) that there are problems depositing it on a fixed cathode. It is much easier to take advantage of its reactivity right at the cathode under the protection of the salt bath and the heat that is already there. I am thinking now that it may be more suitable to use a steel cathode surrounded by loose coal, charcoal, or coke, because the calcium would have trouble diffusing into a dense graphite cathode.

When the cathode racks are pulled from the melt, they would be covered with electrolyte, and the broken up material could then be washed with alcohol or something (as long as it doesn't react with the carbide) to leech out CaCl2 and leave the carbide. If the carbide was just used for generating acetylene, the CaCl2 would not even be a problem if it was all broken up together.

Anyways I am just trying to think of more efficient methods (from an energy standpoint) than the incredibly hot arc furnace. It may be more complicated at a small scale, but beyond mere kilograms it could be economical. I am always interested in exploring the various uses of the technology of fused CaCl2/CaO electrolysis.

[Edited on 28-11-2008 by kilowatt]

Nevermore - 31-12-2008 at 15:42

Quote:

Originally posted by kazaa81
Hallo to all,

I'm looking for CaC2 in Italy, but I haven't find anything. Is it today used?
I don't know, because acetylene lamps aren't used today.
Where and under what name I can buy it (except scientifical suppliers)?

Thanx for help.

[Edited on 3-9-2004 by chemoleo]

Calcium carbide is sold commonly in Italy.
Try looking at the shops that sell equipment for fishing (look for "carburo").
Near the marina or near any fisherman place you will find plenty of it, and cheap, around 6-7€ per Kg.

franklyn - 2-4-2010 at 14:04

I just buy it , but here is simple experimental prospect of easily making it worth a try.
http://www.sciencemadness.org/talk/viewthread.php?tid=13144#...

.

franklyn - 21-5-2010 at 06:55

Here I thought the only way to obtain Aluminum other than reduction of
it's Chlorides with alkali metals was by the Hall electrolysis of bauxite in a
cryolite melt. Alumina Al2O3 can be reduced by acetylides and if it is mixed
with carbon and an amount of catalytic Calcium oxide CaO to first produce
CaC2 , that in turn reduces the Al2O3 yielding Aluminum ! How cool is that !

Al2O3 reduction by CaC2.gif - 19kB

metalresearcher - 18-9-2010 at 07:09

Nice to read all about making CaC2 !
I made CaC2 in an arc furnace using a 150A hardware-shop-at-the-corner welder and crushed marble with charcoal.
When dropping pieces into water it bubbled and the gas, presumably C2H2, burned with a sooting flame.

More info how I did it on my site: www.metallab.net/arcmelt

doofos - 3-8-2013 at 06:22

Friction heater if you don't want to use electricity.

AJKOER - 4-8-2013 at 07:25

A few points. First per Wikipedia (http://en.wikipedia.org/wiki/Acetylide ), to quote:

"Some metal acetylides are traditionally called carbides. For example, lithium carbide and calcium carbide are really derivatives of C2 2−."

Also: "Acetylides of the alkali metals can be prepared by deprotonation of acetylene in liquid ammonia."

In fact, per this source, "A treatise on chemistry, Volume 2, by Henry Enfield Roscoe, Carl Schorlemmer, page 560. link: http://books.google.com/books?id=030GAQAAIAAJ&pg=PA560&a... to quote:

"It [referring to CaC2] is best prepared pure by passing acetylene into liquid ammonia containing metallic calcium [2] and heating the resulting compound, CaC2,C2H2,4NH3, or by the action of acetylene on calcium hydride, the compound CaC2,C2H2, being first formed.[3]"

Interestingly,this manner of preparation of CaC2 closely parallels that for Na2C2 for which it is structurally related. To quote Wikipedia (link http://en.wikipedia.org/wiki/Sodium_carbide ):

"Acetylides
Several carbides are assumed to be salts of the acetylide anion C2 2– (also called percarbide), which has a triple bond between the two carbon atoms. Alkali metals, alkaline earth metals, and lanthanoid metals form acetylides, e.g., sodium carbide Na2C2, calcium carbide CaC2, and LaC2.[1]"

Here is a cited preparation for Na2C2 (see http://sodium.atomistry.com/sodium_carbide.html ), to quote:

"When acetylene reacts with sodium, either in the metallic state, or as hydride, or in solution in liquid ammonia, a substance of the formula C2Na2,C2H2 is produced. When heated in vacuum, or in a current of hydrogen at 220° C., it evolves acetylene, leaving sodium carbide. The carbide is very reactive, readily undergoing decomposition with deposition of carbon, and decomposing water with evolution of acetylene."

This source ( see http://books.google.com/books?id=YyoUNYgBYJoC&pg=SA1-PA1... ) notes that when Ca is dissolved in liquid ammonia, a paramagnetic, highly conducting, highly reducing deep blue liquid is formed, these properties being attributed to the presence of solvated electrons in solution,

[Edited on 4-8-2013 by AJKOER]

NedsHead - 8-9-2016 at 07:28

I knocked up a quick video on making Calcium carbide vie electrolysis this afternoon, it's not great quality but you can get the idea https://www.youtube.com/watch?v=xSAziTIHs3w

NEMO-Chemistry - 8-9-2016 at 14:57

Any good to you?? http://www.ebay.it/itm/Carbide-for-a-caver-or-miners-lamp-ca...

NedsHead - 8-9-2016 at 20:59

Thanks NEMO but no not really, the point was to make it myself. Since I have a working procedure I'll try and scale it up a bit in a purpose built furnace

NEMO-Chemistry - 9-9-2016 at 05:30

Ooops sorry i didnt read it all (*blush*), i thought you were having trouble getting hold of some