Make calcium metal

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I read somewhere that you can make calcium metal by reacting powdered aluminium and calcium sulphate ( from plaster ) in a typical thermite reaction. It just so happens that I want some calcium metal right now, so I thought I'd try it. I crushed up some already set plaster (calcium sulphate nonahydrate I'm pretty sure) and now I plan on heating it until it drys to the dihydrate or anhydride. Which hydrate ( or the anhydride ) do you think would work best? I would guess the anhydride, the water is just one more thing to potentially ruin the batch. I'm really hoping this will work. Anyways, I'll get to it and keep you posted. No matter how trivial it is, I'd like to have your input on this.

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I read somewhere that you can make calcium metal by reacting powdered aluminium and calcium sulphate ( from plaster ) in a typical thermite reaction. It just so happens that I want some calcium metal right now, so I thought I'd try it. I crushed up some already set plaster (calcium sulphate nonahydrate I'm pretty sure) and now I plan on heating it until it drys to the dihydrate or anhydride. Which hydrate ( or the anhydride ) do you think would work best? I would guess the anhydride, the water is just one more thing to potentially ruin the batch. I'm really hoping this will work. Anyways, I'll get to it and keep you posted. No matter how trivial it is, I'd like to have your input on this.

Learn to count water molecules first.

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I read somewhere that you can make calcium metal by reacting powdered aluminium and calcium sulphate ( from plaster ) in a typical thermite reaction. It just so happens that I want some calcium metal right now, so I thought I'd try it. I crushed up some already set plaster (calcium sulphate nonahydrate I'm pretty sure) and now I plan on heating it until it drys to the dihydrate or anhydride. Which hydrate ( or the anhydride ) do you think would work best? I would guess the anhydride, the water is just one more thing to potentially ruin the batch. I'm really hoping this will work. Anyways, I'll get to it and keep you posted. No matter how trivial it is, I'd like to have your input on this.

I just dehydrated the caso4 by heating with a small butane torch (or at least I hope I dehydrated it). The next step would be to mix with al and light it up... but nature had to ruin the fun and start it raining. I'll wait a while for it to stop. In the meantime, I might do a few purity checks on the dehydrated caso4, grind it up a little finer.This is completely random, but when I was heating some stainless steel mesh with the torch, I found that if you press the head of it against the mesh the flame will go through... If you try to pull it away again, the actuall flame will stay on the other side of the mesh. Try it. It looks pretty cool.Oh, sorry I can't get any pictures up for now, my camera is so stubborn.

Learn to count water molecules first.

Did I make an error? It wouldn't surprise me too much. Would you mind pointing it out to me, I don't see it? I've never had an excuse to do anything with calcium sulphate before, so I really don't know too much about it. You may notice I said "pretty sure". Again, thanks for your input.

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Well, it stopped raining a while ago so I attempted the experiment. Sorry I couldn't get back until now.Anyways, it went great! I ended up with a dull, oxidized chunk. I did the thermite reaction on a thick steel slab, which likely sucked heat from the reactants until they stopped prematurely. Over half of it burned though, so I took the resultant piece for primitive testing. It gave a metallic sound when tapped against the aforementioned steel slab. It bubbled at a respectable rate when placed in water, slowly turning the solution cloudy white. The solution reacted vigorously with ~38% HCl. The whole chunk reeked of H2S (maybe some leftover sulphides?) . When scratched, it exposed a shiny metal surface. Sounds like calcium! I used 2:1 sulphate to aluminium ratio for the thermite, standard magnesium ribbon ignition. I got photos, but I can't upload them! Ugh... So frustrating!

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Learn to spot italicisation.

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Learn to spot italicisation.

Does italicising it make a difference? Is that some new convention that I didn't learn in chemistry? I felt like italicising it, so what?Please point out the errors, if any, in a way I can make sense of. Thank you.

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Does italicising it make a difference? Is that some new convention that I didn't learn in chemistry? I felt like italicising it, so what?Please point out the errors, if any, in a way I can make sense of. Thank you.

One last thing before we can be sure what you have is calcium: Flame test?

If it is, congratulations!

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!

Moderator Note

I don't think that arguments over formatting really belong in a thread about calcium metal. Back on topic, please.

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OK, back to the topic.

I really think that trying to prepare calcium by a thermite type reaction is likely to be hazardous.

I therefore do not think it should be done by someone who does not pay attention to what they are doing.

So I don't think that it's a good idea for someone who not only gets utterly the wrong hydration number for Calcium sulphate, but can't spot his error even when it's quoted back at him with the mistake highlighted by italicisation.

It's not an issue of formatting.

It's an issue of watching what you are doing, and thinking it through clearly.

I invite you to consider the reaction of a little trapped water with white hot Al or Ca and calculate the volume of gas (be it H2 or H2O) formed.

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John, I thought I italicized that myself, I did notice and consider that however. Doesn't set plaster have 9 h2o's? That's what my chem teacher taught me. November, Nonagon, Ununnonium, they all involve(d) 9 (obvious, I know).

One last thing before we can be sure what you have is calcium: Flame test?

If it is, congratulations!

Sorry I took so long. Anyways, I filtered and boiled down the remaining non chlorinated precipitate, got a nice bright orange from it! I'd like it if some other people could try this, to give it a little more credibility from their potential confirmations.

OK, back to the topic.

I really think that trying to prepare calcium by a thermite type reaction is likely to be hazardous.

I therefore do not think it should be done by someone who does not pay attention to what they are doing.

So I don't think that it's a good idea for someone who not only gets utterly the wrong hydration number for Calcium sulphate, but can't spot his error even when it's quoted back at him with the mistake highlighted by italicisation.

It's not an issue of formatting.

It's an issue of watching what you are doing, and thinking it through clearly.

I invite you to consider the reaction of a little trapped water with white hot Al or Ca and calculate the volume of gas (be it H2 or H2O) formed.

Agreed, it can be dangerous. Mmm... But John my friend, I think you failed to consider that for ignition, I stick a piece of mg in the pile, put a mix of al, s, & kno3 around it, then use a model rocket remote igniter to back up 20 meters before I light any thermite mixture, plus safety goggles that I modded with a uv filter from the eye doctors. Sounds really excessive, I know, but better excessive than molten metal splattered across your face, right? Back at science madness, we didn't point out things in quotes with italics. I'm a complete noob to these science forums conventions.

OK, back to the topic.

I really think that trying to prepare calcium by a thermite type reaction is likely to be hazardous.

I therefore do not think it should be done by someone who does not pay attention to what they are doing.

So I don't think that it's a good idea for someone who not only gets utterly the wrong hydration number for Calcium sulphate, but can't spot his error even when it's quoted back at him with the mistake highlighted by italicisation.

It's not an issue of formatting.

It's an issue of watching what you are doing, and thinking it through clearly.

I invite you to consider the reaction of a little trapped water with white hot Al or Ca and calculate the volume of gas (be it H2 or H2O) formed.

John, there are nerdy GIRLS out here too.

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OK, so I think that you are not paying a lot of attention to what you do and therefore shouldn't be playing with thermite.

Your response is to point out that you don't know what you wrote and didn't realise you should check.

" I thought I italicized that myself,"

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OK, so I think that you are not paying a lot of attention to what you do and therefore shouldn't be playing with thermite.

Your response is to point out that you don't know what you wrote and didn't realise you should check.

" I thought I italicized that myself,"

To be fair, John Cuthber, people don't expect their own quotes to be tampered with in a reply. To insist that chilled_flourine should pay more attention in this instance is like telling someone you've hidden something in the room they're in, and then chastising them when they fail to check their own pockets.

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To be fair, John Cuthber, people don't expect their own quotes to be tampered with in a reply. To insist that chilled_flourine should pay more attention in this instance is like telling someone you've hidden something in the room they're in, and then chastising them when they fail to check their own pockets.

Thank you phi, for the first bit of support I have been given in my short time here.

OK, so I think that you are not paying a lot of attention to what you do and therefore shouldn't be playing with thermite.

Your response is to point out that you don't know what you wrote and didn't realise you should check.

" I thought I italicized that myself,"

John, "I thought I italicized that myself" was not my justification. The safety precautions I named are. Keep in mind that I was only using a puny 6 gram pile, not exactly the mother of all bombs. If I was truly as ignorant as you think I am, nothing you could say would influence my decisions, therefore you should have given up already. Are you beginning to doubt even yourself? John, if I call a beer a giddleboop, and you call it a beer, but the bartender gives us both beers, does it really matter what we call them if we just want a beer? I would say no. I admit it, I made a mistake. My chemistry teacher was wrong, and since I said what she did, that makes me equally wrong. No, I'm not trying to take the blame away from myself. I could have found out for sure. I just presumed a chem teacher was a valid source, and in this case I was wrong. Either way, I made calcium, which was the purpose of all this. I succeeded (got my metaphorical beer (no, I am not an alcoholic)), debate that.

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Wow, really? With a caesium on top? Even if I wanted to, I couldn't, and the only pics I got were of the glowing slag, it wouldn't satisfy your pyromania one bit.

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What about a current pic of the calcium metal? I've got some we can compare with.

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What about a current pic of the calcium metal? I've got some we can compare with.

Hmm... You do remember that I dissolved it all, right? Guess I could make some more. I already told you that my camera's upload link broke or something, so I "couldn't, even if I wanted to". It was just a dull gray, oxidized chunk anyways, could you really tell if it was calcium or not from such a picture? Where do you get your calcium, elementcollector?

United Nuclear! $10 or something, I ampouled some the other day. Still have plenty left for reactions, etc. I wonder if I could reduce some rare earths with this stuff? EDIT: Incidentally, how did you dehydrate your CaSO4? I blowtorched some of mine in a ceramic bowl, and it didn't *seem* to do anything. Edited by elementcollector1 Link to comment Share on other sites United Nuclear!$10 or something, I ampouled some the other day. Still have plenty left for reactions, etc.

I wonder if I could reduce some rare earths with this stuff?

EDIT: Incidentally, how did you dehydrate your CaSO4? I blowtorched some of mine in a ceramic bowl, and it didn't *seem* to do anything.

Personally, I just heat it up in a furnace, or if I'm short for time I blowtorch it until its red hot. The temporary glow is what tells me it is done.United nuclear is great, but I try to avoid ordering from there. I used to add sulphuric and distill, but that's dangerous, and I'm out of good sulphuric now.

Edited by chilled_fluorine
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• 1 month later...

I don't think any Ca metal is made at all, not just because Ca is more electropositive than Al (there can be exceptions to that, like making Na from Mg), but because of different reasons.

Firstly, let's assume Ca metal was made. Aluminium sulfate would be a by-product. Usually, it is quite stable, but we're talking about thermite temperatures here. At that temperature, it will decompose to form Al2O3, SO2 and oxygen. Both the SO2 and oxygen can and will react with any calcium formed, especially at such a high temperature.

Second, remember that although sulfates are not typically regarded as oxidizers, they can act as oxidizing agents at high temps. For example, Na2SO4 is reduced to Na2S easily in a furnace when roasted with charcoal. It is far more energetically favourable for aluminium metal to reduce the sulfate to sulfide, instead of actually "stealing" off the sulfate anion. Any potential calcium metal formed will also react with the sulfate quickly to form oxides of calcium and sulfides.

So, at the end, instead of calcium metal, there is a mix of calcium and aluminium sulfides and oxides.

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I don't think any Ca metal is made at all, not just because Ca is more electropositive than Al (there can be exceptions to that, like making Na from Mg), but because of different reasons.

Firstly, let's assume Ca metal was made. Aluminium sulfate would be a by-product. Usually, it is quite stable, but we're talking about thermite temperatures here. At that temperature, it will decompose to form Al2O3, SO2 and oxygen. Both the SO2 and oxygen can and will react with any calcium formed, especially at such a high temperature.

Second, remember that although sulfates are not typically regarded as oxidizers, they can act as oxidizing agents at high temps. For example, Na2SO4 is reduced to Na2S easily in a furnace when roasted with charcoal. It is far more energetically favourable for aluminium metal to reduce the sulfate to sulfide, instead of actually "stealing" off the sulfate anion. Any potential calcium metal formed will also react with the sulfate quickly to form oxides of calcium and sulfides.

So, at the end, instead of calcium metal, there is a mix of calcium and aluminium sulfides and oxides.

Disagree.

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Disagree.

Why don't you agree? You can't just say "disagree" without explaining your reasoning. Care to explain why it would be favourable for calcium metal to form and not be destroyed instantly?

By the way, another reason why no calcium metal is formed: The exothermic reaction. The reduction of Ca2+ by Al, if it even happens at all, would be NOWHERE NEAR as exothermic as the CaSO4+Al thermite. But the oxidation of aluminium from another oxidizing agent, the sulfate ion itself, which loses oxygen at thermite temperatures even without a reducing agent, is much more likely to be the cause of the exothermic reaction.

Yet another reason. The reason why magnesium reacts with sodium hydroxide is because of covalent bonding. Magnesium partially covalently bonds to its oxygen, along with ionic bonding. Sodium ionically bonds strongly to oxygen, but hardly covalently bonds at all. So the additional covalent bonding formed is what makes this reaction energetically favourable. But think of calcium. I would think that it would also partially covalently bond to its oxygen, along with a strong ionic bonding. So Ca2+ oxidation of aluminium would not be energetically favourable (or favourable at all, unless you distil off the molten calcium metal).

The formation of H2S that you observed is perfectly consistent with my hypothesis that sulfides are formed instead of calcium metal. But you have one more test, light it with a torch. If any calcium metal is formed, it would burn with an orange flame after you stop heating it with the torch. A flame test will only show the presence of calcium, not whether it is in the form of a metal or a compound, so that would not work.

Edited by weiming1998
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Why don't you agree? You can't just say "disagree" without explaining your reasoning. Care to explain why it would be favourable for calcium metal to form and not be destroyed instantly?

By the way, another reason why no calcium metal is formed: The exothermic reaction. The reduction of Ca2+ by Al, if it even happens at all, would be NOWHERE NEAR as exothermic as the CaSO4+Al thermite. But the oxidation of aluminium from another oxidizing agent, the sulfate ion itself, which loses oxygen at thermite temperatures even without a reducing agent, is much more likely to be the cause of the exothermic reaction.

Yet another reason. The reason why magnesium reacts with sodium hydroxide is because of covalent bonding. Magnesium partially covalently bonds to its oxygen, along with ionic bonding. Sodium ionically bonds strongly to oxygen, but hardly covalently bonds at all. So the additional covalent bonding formed is what makes this reaction energetically favourable. But think of calcium. I would think that it would also partially covalently bond to its oxygen, along with a strong ionic bonding. So Ca2+ oxidation of aluminium would not be energetically favourable (or favourable at all, unless you distil off the molten calcium metal).

The formation of H2S that you observed is perfectly consistent with my hypothesis that sulfides are formed instead of calcium metal. But you have one more test, light it with a torch. If any calcium metal is formed, it would burn with an orange flame after you stop heating it with the torch. A flame test will only show the presence of calcium, not whether it is in the form of a metal or a compound, so that would not work.

The only proof I need is what I saw. And what I saw was a chunk of calcium. Try it yourself, but I have better things to do than explain myself to doubters. Until you've tried it (and even then you can't be sure), you can't say anything against it. Btw, I dissolved it all in hcl, 'member?

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The only proof I need is what I saw. And what I saw was a chunk of calcium. Try it yourself, but I have better things to do than explain myself to doubters. Until you've tried it (and even then you can't be sure), you can't say anything against it. Btw, I dissolved it all in hcl, 'member?

People "see" UFO's but that doesn't make them true; did you assay it? Explaining yourself to doubters is an essential part of what science is all about...ever heard of peer review?

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