Sciencemadness Discussion Board

Limestone for CaCo3

CHRIS25 - 30-4-2012 at 10:31

I have read so many times that you can react Limestone with HCL to get calcium chloride. However none of these sites mentioned that there are different types of limestone. Clean unbedded, clean bedded, some with magnesium carbonate others yet still with even more chemicals interlaced. So is this an irresponsible suggestion.

I ask because where I live has a high concentration of clean unbedded limestone and was thinking about simply taking a spade and doing a little dig, you know that's how chemistry was always done right? (although upon seeking a definition of all these terms on google I turned up nothing except complex geological surveys with even more complex terminology), anyway, surely limestone can be of any purity and unreliable?
I am assuming that Calcium carbonate (that I have already made from my seashells) and sodium chloride is a more reliable method?

Oh and buying rock salt is not an option, since the little bit of rock salt that I have seems to be sodium chloride, albeit not for human consumption.

Regards


[Edited on 30-4-2012 by CHRIS25]

[Edited on 30-4-2012 by CHRIS25]

Hexavalent - 30-4-2012 at 10:43

Adding sodium chloride to calcium carbonate will not produce calcium chloride.

Calcium carbonate is often available from building suppliers or garden/lawn stores. It can also be prepared by adding a soluble calcium salt to sodium carbonate, although since you haven't got CaCl2 I assume you have no other soluble calcium salts; the nitrate is sometimes available in agricultural stores.

The best way of preparing calcium chloride, short of either buying it from a supplier or looking on eBay or looking in DampRid packs near you, is simply adding calcium carbonate to the acid, the latter of which can be purchased from most hardware stores.

IMO, calcium carbonate is one of the basic chemicals (excuse the pun) that any lab should have in their stock.

[Edited on 30-4-2012 by Hexavalent]

CHRIS25 - 30-4-2012 at 11:27

Hi Hexavalent, was that a typing error: sodium chloride to calcium chloride will not produce calcium chloride? I thought Caco3 and NaCl would give you a soluble CaCl? anyway thanks. I don't have a basic lab yet but sure - trying to build one.

Hey just as an off-topic curiosity: "Nothing is a fact unless it can be proven." Surely not? The inability to prove something "Is" is often down to the incorrect or misguided parameters by which we set out to measure something in the first place? So logically a "Fact" can still be a fact without its empirical support?

barley81 - 30-4-2012 at 11:38

Adding calcium carbonate to sodium chloride does not produce soluble calcium chloride. Adding HCl converts the carbonate ion to carbon dioxide gas, which escapes, driving the reaction forward. HCl destroys the carbonate ion so that the calcium carbonate can dissolve. NaCl does not.

Good luck in building your lab!!!

Debate!!!!!! One might be able to argue that for any fact that you say has no empirical evidence behind it, there is actually empirical evidence. I wonder if it's possible to win the debate that way.

CHRIS25 - 30-4-2012 at 11:48

Yes just goes to show how much I have yet to learn. I think I had better go to the builders!!

Mmm, I suppose that means that anything can be a fact, even cinderella, we just have to find the empirical evidence. But obviously that is silly, that leaves everybody to claim anything is fact.

watson.fawkes - 30-4-2012 at 17:58

Most limestone has significant Mg in it, not so much as dolomite, obviously, but it's very unlikely to be pure Ca. If the mixed alkali earth salt is OK for your application, this won't matter. Otherwise you have a purification issue and possibly a separation one, if the Mg concentration is too high to economically use the purification methods.

CHRIS25 - 30-4-2012 at 18:49

Thanks watson, Mmm, precisely.

Vikascoder - 3-5-2012 at 02:29

If you want to make calcium chloride you can make it buying bleaching powder then heating it until it gives white precipitate. Important thing . This process will not make calcium chlorate because calcium chlorate made by disproportion generally decompose to calcium chloride

m1tanker78 - 3-5-2012 at 04:43

Buy a sack of hydrated lime at your local building store. It's literally cheaper than dirt and a convenient starting material for making other calcium salts. While you're there, pick up a gallon or two of hydrochloric acid. If you want calcium chloride without the hassle of boiling down a solution, pick up some damp rid.

Tank

CHRIS25 - 3-5-2012 at 07:47

calcium oxide is obtained from calcium carbonate , How? Because I have plenty of that, and I do not need to buy the calcium oxide (Slaked lime)

A visit to the builders is coming soon, so we'll see what I can find. I have never seen Bleaching powder in Ireland Vikascoder. Regards.

[Edited on 3-5-2012 by CHRIS25]

[Edited on 3-5-2012 by CHRIS25]

Hexavalent - 3-5-2012 at 08:01

The calcium carbonate is heated to a very high temperature IIRC to produce calcium oxide and carbon dioxide gas;

CaCO3 ---> CaO + CO2

Note, however, that slaked lime is actually calcium HYDRoxide, Ca(OH)2.

CHRIS25 - 3-5-2012 at 09:13

Ah of course should have known that about the slaked lime. So easy, heat the calcium carbonate - I should have guessed being that most oxides are achieved, I believe, as a result of temperature changes as opposed to mixing with another ingredient.

Hexavalent - 3-5-2012 at 10:23

Yes, but it must be heated to a very high temperature to obtain this. This is why CaO is often referred to as 'burnt lime'.

CHRIS25 - 3-5-2012 at 12:51

Yes 850 thereabouts - I have a torch that reaches 1000c so that should not be a problem, I assume heating in cast iron pot is ok.

Hexavalent - 3-5-2012 at 13:51

Yes, the torch can reach that temperature but the question is can it actually sustain such high temperatures on the calcium carbonate?

I can't be certain about heating in your cast iron pot, but personally I would try using a ceramic vessel and heating carefully to eliminate ANY problems with the iron reacting with the air at those high temperatures.

I also assume that upon cooling the reaction product would have to be covered to prevent the extremely hot CaO from reacting to produce Ca(OH)2??

MagicJigPipe - 3-5-2012 at 20:35

Converting CaCO3 to CaO will be much harder than you think. Like Hexavalent said, even if your torch can go to 1500*C, can it heat up the vessel and the carbonate to ~850? It will take a while and you have to have a way of covering it up so that it doesn't react with the water in the air while it's cooling (I know I'm kind of just restating what hexavalent said but if I take this out my paragraph looks flaccid). That shouldn't be too difficult though. The hard part is the heating and all the complications that go with it.

It's not impossible though and I hope you succeed. Let us know how it goes and avoid setting fire to living things or personal property. And wear goggles. Damp powders have a tendency of "exploding" when heated quickly.

CHRIS25 - 4-5-2012 at 04:23

Hi, yes you are probably right, I have the heat to do that actually with something else but containment is a problem. I am not going to make this difficult on myself.

CHRIS25 - 4-5-2012 at 04:53

Quote: Originally posted by Vikascoder  
If you want to make calcium chloride you can make it buying bleaching powder then heating it until it gives white precipitate. Important thing . This process will not make calcium chlorate because calcium chlorate made by disproportion generally decompose to calcium chloride


I wish you had mentioned earlier that bleaching powder was calcium oxychloride!!!

I also see that it contains calcium hypochlorite, and that it is this chemical that when mixed with HCL gives you the calcium chloride, unfortunately the Hydroxide - chloride - hypochlorite ratios in this product dont seem to make it viable? At least I really do not know what happens if you heat this suff in a saucepan??

[Edited on 4-5-2012 by CHRIS25]

[Edited on 4-5-2012 by CHRIS25]

weiming1998 - 4-5-2012 at 05:25

Quote: Originally posted by CHRIS25  
Quote: Originally posted by Vikascoder  
If you want to make calcium chloride you can make it buying bleaching powder then heating it until it gives white precipitate. Important thing . This process will not make calcium chlorate because calcium chlorate made by disproportion generally decompose to calcium chloride


I wish you had mentioned earlier that bleaching powder was calcium oxychloride!!!

I also see that it contains calcium hypochlorite, and that it is this chemical that when mixed with HCL gives you the calcium chloride, unfortunately the Hydroxide - chloride - hypochlorite ratios in this product dont seem to make it viable? At least I really do not know what happens if you heat this suff in a saucepan??

[Edited on 4-5-2012 by CHRIS25]

[Edited on 4-5-2012 by CHRIS25]


Yes, heat bleaching powder, then dissolve the residue in water. Contaminants like Ca(OH)2 and CaCO3 will precipitate while CaCl2 will stay in solution because it is very soluble. A filtration will separate the fairly pure CaCl2 from the impurities. If you want purer CaCl2 for more sensitive applications, recrystallize, which basically means taking the CaCl2 solution, boiling it down until crystals form, then chill the solution and harvest the crystals. Repeat for increased purity.

CHRIS25 - 4-5-2012 at 06:28

Ah thankyou Welming. Now I have a choice... Do i do this, the bleach reaction or this one :
CaCo3+2HCL+H2O2

Could someone just check that I understand things correctly (I am still learning so need to double check my own understanding). I want to know how much Calcium Carbonate will dissove in a 12 Mole solution of HCL. So I take the 12m and multiply that by a 1m CaCo3 divided by a 2m HCL? Answer is well 6 moles of CaCo3. Am I doing things right here?

Having said that I may well do both reactions.

Thankyou

[Edited on 4-5-2012 by CHRIS25]

adamsium - 4-5-2012 at 07:17

Quote: Originally posted by CHRIS25  
Ah thankyou Welming. Now I have a choice... Do i do this, the bleach reaction or this one :
CaCo3+2HCL+H2O2

Could someone just check that I understand things correctly (I am still learning so need to double check my own understanding). I want to know how much Calcium Carbonate will dissove in a 12 Mole solution of HCL. So I take the 12m and multiply that by a 1m CaCo3 divided by a 2m HCL? Answer is well 6 moles of CaCo3. Am I doing things right here?

Having said that I may well do both reactions.

Thankyou

[Edited on 4-5-2012 by CHRIS25]


I'm assuming you're asking how much calcium carbonate will react with the HCl. As you can see from the reaction stoichiometry, one mole of calcium carbonate will react per two moles of acid. So, if you were to use 1L of 12mol/L HCl, 6 moles of calcium carbonate would react (assuming a complete reaction), as the ratio moles of HCl : moles of calcium carbonate is 2:1. As the molecular weight of calcium carbonate is 100.09g/mol, 6 moles equates to 600.5g. From this, you can calculate the appropriate amount of calcium carbonate using simple ratios. e.g, if you use 100mL of 12M HCl, you would use 60g of calcium carbonate, or for 175mL of acid, use 105.1g of calcium carbonate, etc. Essentially, the ratio moles of HCl : mass of calcium carbonate is 1mol : 50g and, as already implied, the ratio for a 12mol/L HCL solution is 100mL HCl : 60g calcium carbonate.

You probably want the acid to be in excess, though, meaning you'd use slightly less calcium carbonate or slightly more acid than these stoichiometric quantities, as it's unlikely to react exactly as you calculate it. You don't want any relatively insoluble calcium carbonate remaining.

Each mole of 'reaction' (i.e. for each mole of calcium carbonate) will yield one mole of calcium chloride. Using the above example of 100mL of HCl, this would mean that you have used 1.2 moles of HCl (i.e. 1/10 of 1L of a 12M soln.) and 0.6 moles of calcium carbonate, so will produce 0.6 moles of calcium chloride, which, if anhydrous, would have a weight of around 66.6g, as the molar mass of anhydrous calcium chloride is ~111g/mol.

CHRIS25 - 4-5-2012 at 07:52

Yep that clears things up a bit. So just clearing my way a bit here:

In the following example: Copper and HCL for copper chloride. Cu+2HCL=CuCl2 So going with the 12m HCL still I worked this out:

6 moles of copper is 381g; to 1000ml HCL. Therefore: 38.1 g Cu + 100ml HCL gives me 11,1g of copper chloride.?.?

Hexavalent - 4-5-2012 at 07:53

Well said Adamsium. Chris, as I mentioned upthread you could try using a ceramic vessel for the heating.

Also, please use the edit feature as opposed to double-posting. The latter only serves to bolster your post count.

adamsium - 4-5-2012 at 09:16

Quote: Originally posted by CHRIS25  
Yep that clears things up a bit. So just clearing my way a bit here:

In the following example: Copper and HCL for copper chloride. Cu+2HCL=CuCl2 So going with the 12m HCL still I worked this out:

6 moles of copper is 381g; to 1000ml HCL. Therefore: 38.1 g Cu + 100ml HCL gives me 11,1g of copper chloride.?.?


No, not quite. A couple of things. First, my understanding is that elemental copper won't react with HCl in general. This would be due to elemental copper having a higher standard reduction potential than hydrogen (0.00000V for hydrogen). Essentially, the copper is not able to be oxidised by the chlorine as it is unable to displace the hydrogen since the hydrogen is a stronger reductor than the copper metal. You can find this information in standard redox potential tables. You should be able to form copper chloride by using copper carbonate in place of elemental copper metal. You will produce aqueous copper chloride, water, with the evolution of carbon dioxide gas. Just filter (probably not essential) and crystallise. Recrystallise for increased purity.

Also, something is out with your molar masses. Just a tip for future use - from what you wrote, "38.1 g Cu + 100ml HCL gives me 11,1g of copper chloride", can you now see why it is obviously wrong, without even calculating anything? If you were to completely react 38.1g of copper metal, ADDING the mass of the chloride to it, you will see an increase in mass (of the copper 'compound' - initially elemental copper, then copper chloride), not a decrease. You'd have to be doing some pretty nifty nuclear chemistry to do that (lose mass), in which case you wouldn't have copper-anything anymore... but anyway. :o

The molar mass of copper (II) chloride is 134.4g/mol (SI Chemical Data, 6th Ed). For the dihydrate, the molar mass is 170.5g/mol. Since the reaction between copper metal and HCl is not going to happen, this is a moot point. Regardless, as shown, that reaction would yield 1mol of copper (II) chloride per mole of copper metal used (assuming an excess or stoichiometric quantity of acid).

EDIT: I also found this. You may find it helpful and easier than redox potentials. http://en.wikipedia.org/wiki/Activity_series

[Edited on 4-5-2012 by adamsium]

CHRIS25 - 4-5-2012 at 12:16

Quote: Originally posted by Hexavalent  
Well said Adamsium. Chris, as I mentioned upthread you could try using a ceramic vessel for the heating.

Also, please use the edit feature as opposed to double-posting. The latter only serves to bolster your post count.


Hi Sorry, but what do you mean "double posting" I'm lost here. I always simply type a reply at the bottom or if I typed and posted and made a mistake I simply use "edit" have no idea what I have done wrong?

CHRIS25 - 4-5-2012 at 12:27

Hi Adamsium, no you are right - absolutely. However I should have told you that I was adding Hydrogen Peroxide, and as long as I keep that topped up copper chloride will form for as long as I want.
So the complete equation is (sorry my fault): Cu + 2HCL + H2O2 = CuCl2 + 2H2O, then as this reacts I get CuCl2 + Cu = 2CuCl.

That list you pointed me to I have as a print out. Problem is my knowledge of everything is weak but growing and I often do not really know when to look at what. If you can understand that.

Many appreciations though for taking the time to help and correct me.

Hexavalent - 4-5-2012 at 13:30

You're welcome, after all we're all here to learn.

What is meant by double posting is what you've just done now - even if you have finished talking about one thing, do not post again for a new topic or for a continuation. Your past two posts are an example. If you wish to add more info, use the edit feature, as opposed to adding a new post.

adamsium - 4-5-2012 at 20:47

Quote: Originally posted by CHRIS25  
Hi Adamsium, no you are right - absolutely. However I should have told you that I was adding Hydrogen Peroxide, and as long as I keep that topped up copper chloride will form for as long as I want.
So the complete equation is (sorry my fault): Cu + 2HCL + H2O2 = CuCl2 + 2H2O, then as this reacts I get CuCl2 + Cu = 2CuCl.

That list you pointed me to I have as a print out. Problem is my knowledge of everything is weak but growing and I often do not really know when to look at what. If you can understand that.

Many appreciations though for taking the time to help and correct me.


Ok, that makes sense. Although, I'm not sure what you mean by that last equation. I found a link to a page that you might find useful for this. I believe this is the blog of a forum member. http://thehomechemist.com/blog/cucl2synthesis/

CHRIS25 - 4-5-2012 at 23:34

Ok Hexavalent. no problem, though when I do it - it is actually without thinking. I promise you I have no interest in being in competition, especially since it would take me years to learn what most poeple on this forum already know in just casual conversation - and that is before they get technically serious, (:

Adamsium: Hi, I understand that HCL is consumed and eaten up in the first part of the reaction. CuCl is the byproduct but upon being revitalised by the H2O2 it turns into CuCl2, should I say it gets re-oxidised again, I suppose the two equations are like a circle. Please feel free to correct me though....

I am a Copper metal worker, (Artistic not industrial) and wish to use this reaction to do Etching, instead of the Ferric chloride which is a wasteful product and more hazardous than this reaction. (I can neutralise the first solution after months of use with Sodium Carbonate and then it becomes safe for the sink, not so with ferric chloride after it is laden with copper chloride). Well this is how at this moment I understand things.

weiming1998 - 5-5-2012 at 00:10

Quote: Originally posted by CHRIS25  
Ok Hexavalent. no problem, though when I do it - it is actually without thinking. I promise you I have no interest in being in competition, especially since it would take me years to learn what most poeple on this forum already know in just casual conversation - and that is before they get technically serious, (:

Adamsium: Hi, I understand that HCL is consumed and eaten up in the first part of the reaction. CuCl is the byproduct but upon being revitalised by the H2O2 it turns into CuCl2, should I say it gets re-oxidised again, I suppose the two equations are like a circle. Please feel free to correct me though....

I am a Copper metal worker, (Artistic not industrial) and wish to use this reaction to do Etching, instead of the Ferric chloride which is a wasteful product and more hazardous than this reaction. (I can neutralise the first solution after months of use with Sodium Carbonate and then it becomes safe for the sink, not so with ferric chloride after it is laden with copper chloride). Well this is how at this moment I understand things.


That (etching copper with CaCl2), unfortunately, will not work.

As described by this site: http://www.p-m-services.co.uk/ferric_chloride.htm
the etching process proceeds by the oxidation of the copper to insoluble copper(I) chloride , then to a soluble copper (II) chloride. This depends on the Fe3+ ion, as it acts as an oxidizing agent, easily reduced to Fe2+.

Ca2+, on the other hand, cannot be either oxidized or reduced (unless by a metal more electropositive than calcium) , which boils down to unable to be reduced in aqueous solution at all. If it cannot oxidize the copper, how can you use it to etch the copper?

If you are just looking for a better, less hazardous etching agent, use dilute nitric acid, an acid+H2O2, or even bleach+vinegar (although the solution is unstable and will decompose into Cl2, making it on-site and dropping the copper in should be reasonable.). The waste products can then be neutralized with baking soda and the copper carbonate extracted and disposed separately.

CHRIS25 - 5-5-2012 at 02:53

Hi Welming, Mmm, I know i have a lot to learn, and I will be studying a bit more stuff here. But I have already tried an experiment with that formula and what happens is that the copper that is left exposed in the solution (After I have added a resisit) dissolves away. Effectively leaving raised parts which is your design or your writing.

[Edited on 5-5-2012 by CHRIS25]

weiming1998 - 5-5-2012 at 06:27

Quote: Originally posted by CHRIS25  
Hi Welming, Mmm, I know i have a lot to learn, and I will be studying a bit more stuff here. But I have already tried an experiment with that formula and what happens is that the copper that is left exposed in the solution (After I have added a resisit) dissolves away. Effectively leaving raised parts which is your design or your writing.

[Edited on 5-5-2012 by CHRIS25]


Did you mean that the CaCl2 solution worked and etched the copper? Or do you mean the acid+peroxide did?

If the CaCl2 worked, then this is something undiscovered, and I will try it myself.

CHRIS25 - 5-5-2012 at 12:10

Hi Welming, no I had to add the peroxide. I used an 8m sol of hcl (24%) and 50/50 with peroxide. I added the copper and it etched.

weiming1998 - 5-5-2012 at 21:01

Quote: Originally posted by CHRIS25  
Hi Welming, no I had to add the peroxide. I used an 8m sol of hcl (24%) and 50/50 with peroxide. I added the copper and it etched.


Yes, that would etch. The CuCl2 formed will oxidize the copper to CuCl as well. So it will continue etching until all the green solution has exhausted to a white precipitate.

[Edited on 6-5-2012 by weiming1998]