Chemistry Alchemist
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Calcium Nitrate from Magnesium Nitrate
Hello fellow smart people its me again 
Magnesium nitrate is a fairly common chemical i can get my hands on for a cheap price for about 500grams, Calcium nitrate on the other hand is pretty
hard to get and it could be a very fun and useful chemical for pyrotechnics or just a good nitrate, its hard to get my hands on becuase i dont have
nitric acid so i cant simply add calcium carbonate to nitric acid to get Calcium Nitrate, so i have been thinking how can i make it out of Magnesium
Nitrate. Magnesium Hydroxide and Carbonate are both insoluble so if i could get something like Calcium Carbonate or hydroxide and mix it with
Magnesium nitrate maybe it will precipitate Magnesium OH or CO3, but then i relised wont work due to both the Ca(OH)2 and CaCO3 are insoluble so it
wont work... So it got me thinking even more... what is a soluble calcium salt which i can precipitate the magnesium and get calcium nitrate. Then it
hit me... Calcium Bicarbonate, It is soluble in water 16grams at 0 Deg C or 18 grams at 100 Deg C. This is where a question needs to be answered. Does
this reaction work.
CaCO<sub>3</sub> + CO<sub>2</sub> + H<sub>2</sub>O --> Ca(HCO<sub>3</sub> <sub>2</sub>
If this reaction does work then would it be possible to make a solution of Magnesium nitrate and have the freshly prepared Calcium bicarbonate in
excess and mix the 2 together as the following reaction.
Mg(NO<sub>3</sub><sub>2</sub> +
Ca(HCO<sub>3</sub><sub>2</sub> -->
MgCO<sub>3</sub> + Ca(NO<sub>3</sub><sub>2</sub> + CO<sub>2</sub> + H<sub>2</sub>O
Does all this seem to be right?
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weiming1998
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Quote: Originally posted by Chemistry Alchemist  | Hello fellow smart people its me again
Magnesium nitrate is a fairly common chemical i can get my hands on for a cheap price for about 500grams, Calcium nitrate on the other hand is pretty
hard to get and it could be a very fun and useful chemical for pyrotechnics or just a good nitrate, its hard to get my hands on becuase i dont have
nitric acid so i cant simply add calcium carbonate to nitric acid to get Calcium Nitrate, so i have been thinking how can i make it out of Magnesium
Nitrate. Magnesium Hydroxide and Carbonate are both insoluble so if i could get something like Calcium Carbonate or hydroxide and mix it with
Magnesium nitrate maybe it will precipitate Magnesium OH or CO3, but then i relised wont work due to both the Ca(OH)2 and CaCO3 are insoluble so it
wont work... So it got me thinking even more... what is a soluble calcium salt which i can precipitate the magnesium and get calcium nitrate. Then it
hit me... Calcium Bicarbonate, It is soluble in water 16grams at 0 Deg C or 18 grams at 100 Deg C. This is where a question needs to be answered. Does
this reaction work.
CaCO<sub>3</sub> + CO<sub>2</sub> + H<sub>2</sub>O --> Ca(HCO<sub>3</sub><sub>2</sub>
If this reaction does work then would it be possible to make a solution of Magnesium nitrate and have the freshly prepared Calcium bicarbonate in
excess and mix the 2 together as the following reaction.
Mg(NO<sub>3</sub><sub>2</sub> +
Ca(HCO<sub>3</sub><sub>2</sub> -->
MgCO<sub>3</sub> + Ca(NO<sub>3</sub><sub>2</sub> + CO<sub>2</sub> + H<sub>2</sub>O
Does all this seem to be right?
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Unlike the alkali metal bicarbonates, alkali earth bicarbonates (or indeed any metallic bicarbonates apart from the alkali metals) is extremely
unstable due to the bicarbonate ion decomposing to carbonate, H2O and CO2 in the presence of even a mildly acidic cation, because of how weak an acid
H2CO3 is. The reaction of CO2 and H2O to form Ca(HCO3)2 indeed works (as demonstrated by bubbling excess CO2 through lime water, the precipitate
disappears), but calcium bicarbonate is very unstable. It will decompose readily, especially in high concentrations (calcium bicarbonate exists in
very dilute solutions in "hard" water and other water sources) and cannot be isolated. Magnesium bicarbonate is slightly more unstable than calcium
bicarbonate (you can predict this by the increased acidity of the Mg2+ ion) but can still possibly exist in solution (sorry, can't provide references,
because all the search result relates to some bicarbonate drink). It would be difficult to create an adequately concentrated solution of Ca(HCO3)2 to
perform the double displacement reaction with magnesium nitrate that you suggested, and possible complications could occur with soluble magnesium
bicarbonate and magnesium carbonate hydrate as well. So, this idea is not good practically.
It is difficult to pick an insoluble magnesium salt that has the same anions as a soluble calcium salt, so I don't think double displacements are the
way to go. Try making nitric acid with the magnesium nitrate, then react with Ca(OH)2/CaCO3.
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AJKOER
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Fine comments and feedback by Weiming1998.
However, before you completely bury your CaCO3 idea, to be complete, you may consider mixing on a small scale a fresh precipitate of Calcium carbonate
with hot aqueous magnesium nitrate.
My reasoning is I believe I have read about at least one reaction that uses a fresh precipitate of Calcium carbonate to effect a reaction that would
otherwise not proceed. Most likely still won't work, but may be worth the effort as you do have a half a kilo of the stuff.
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Chemistry Alchemist
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i know that calcium bicarbonate is unstable and can easly convert back to carbonate, so i was saying making a new batch of bicarbonate and then
straight away filter it directly into magnesium nitrate
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bbartlog
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I believe magnesium salts tend to be more soluble than their calcium counterparts, so it is unlikely that you can find a way to selectively
precipitate the magnesium while leaving the calcium in solution. I think your best bet if you have the equipment is to add H2SO4 (to the magnesium
nitrate) and distill off the nitric acid, at which point you can react it with any one of a number of calcium salts to yield calcium nitrate.
The less you bet, the more you lose when you win.
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Chemistry Alchemist
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Well i was thinking, this reaction works with sodium bicarbonate and hydroxide so why cant it work with calcium bicarbonate. I dont have a good source
of H2SO4, only way to buy that is from a brand new car battery which is too expensive at this current time, and i dont have the glass ware to make
proper acid, id only be able to make a kinda sucky nitric acid
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Lithium
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at cooler temperatures, calcium formate is more soluble than magnesium formate
http://en.wikipedia.org/wiki/Solubility_table
( at 0 degrees C, Mg formate dissolves 14g per 100mls, whereas Ca formate dissolves 16.1g per 100mmls
oxalic acid reacts with glycerine to form formic acid (which can be distilled off)
http://www.erowid.org/archive/rhodium/chemistry/formic.acid....
calcium formate can also be formed via Ca(OCl)2 and acetaldehyde, which in turn may be formed from Ca(OCl)2 and ethanol
formic acid and CaCO3 react to form calcium formate, CO2 and H2O
[Edited on 26-7-2012 by Lithium]
Li
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Chemistry Alchemist
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Wouldnt mine making Formic acid, it was on my list of things to do for youtube, if i can make all that with out Proper glassware.... id do it
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ldanielrosa
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True calcium hydroxide solubility is low, but magnesium hydroxide solubility is lower per http://en.wikipedia.org/wiki/Solubility_table .
I'm surprised you can't get Ca(NO3)2.4H2O at the agriculture shop.
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weiming1998
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I made a video on Youtube about making formic acid using calcium hypochlorite, ethanol and oxalic acid. Yield was about 50 ml of a slightly
contaminated, a bit watered-down acid from lots of calcium hypochlorite (no scale) and about 80 ml ethanol (approximate). I'd distil it if I had an
efficient distillation setup, but mine was a very crude one involving a rubber tube with a cork on a flat-bottomed flask, that works better as a gas
bubbler. You don't actually need very complex equipment; a gas bubbler (which I talked about before, and you can make out of an ordinary glass bottle,
cork and a rubber tube) and a few beakers was sufficient. Here is my video that has all the procedures: http://www.youtube.com/watch?v=Bx584hCfWHQ&feature=g-upl
Edit: Thanks for subscribing!
[Edited on 26-7-2012 by weiming1998]
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Chemistry Alchemist
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I subbed to you btw
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bbartlog
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Interesting. My first reaction was to think that's hardly useful, since you can't really make up a solution with practical quantities of Ca(OH)2...
however, on further thought I recall that metathesis with (somewhat) insoluble inputs has been used industrially. In the 19th century, ammonium
sulfate was prepared by filtering aqueous ammonium carbonate through gypsum (in layers supported by canvas). The calcium carbonate is sufficiently
less soluble than the calcium sulfate that the reaction proceeds, producing ammonium sulfate and CaCO3.
Similarly, maybe you could run a hot solution of magnesium nitrate through a bed of Ca(OH)2 (held in a coffee filter or the like), repeatedly, until
you had achieved sufficient deposition of Mg(OH)2 and dissolution of calcium in solution.
The less you bet, the more you lose when you win.
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What about Boiling the 2 together? a very tiny bit of calcium hydroxide is soluble, so what if when that tiny put goes in solution, it reacts to form
magnesium hydroxide, and that gives more calcium hydroxide to dissolve?
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bbartlog
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Should work so long as the Ca(OH)2 is a sufficiently fine powder. The bane of such reactions is that the solid phase gets coated with the insoluble
product, i.e. if your calcium hydroxide is in larger particles then they'll just get completely covered in magnesium hydroxide and the reaction will
come to a halt.
The less you bet, the more you lose when you win.
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AJKOER
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| Quote: Originally posted by bbartlog | | Should work so long as the Ca(OH)2 is a sufficiently fine powder. The bane of such reactions is that the solid phase gets coated with the insoluble
product, i.e. if your calcium hydroxide is in larger particles then they'll just get completely covered in magnesium hydroxide and the reaction will
come to a halt. |
Again the same concept as I noted previously, I would react CaCl2 ( DampRid is a commercially available product) with NH4OH, or better heat impure
NH4OH and lead the NH3 gas into a solution of CaCl2. Decant and dilute repeatedly to maintain the Ca(OH)2 as a suspension and to remove the highly
soluble NH4Cl impurity. Reaction:
2 NH3 + 2 H2O + CaCl2 --> Ca(OH)2 (s) + 2 NH4Cl
Then, use this very fine suspension of Ca(OH)2 in your proposed reaction with Mg(NO3)2.
[Edited on 27-7-2012 by AJKOER]
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bbartlog
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CaCl2 forms complexes with NH3. If you think about it, it's hardly likely that you could react a very slightly acidic compound (CaCl2) and a weak base
(NH4OH) and obtain a more acidic solution (NH4Cl) and a stronger base (Ca(OH)2). I would assume that the reaction runs the other way and that mixing
Ca(OH)2 and NH4Cl in solution would result in the production of ammonia, water and CaCl2.
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AJKOER
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bbartlog:
You may be right with completely pure starting chemicals. What I first believed was that anhydrous CaCl2 could undergo a partial (but fully
exothermic) hydrolysis with water, for example:
CaCl2 + 2 H2O ---> Ca(OH)2 (s) + 2 HCl (g)
and the NH3 could move the reaction further to the right by removing any HCl in solution.
[EDIT] However, on further thought, it is more likely that when I actually performed this reaction there was probably some CO2 around (in the tap
water or the NH4OH), so the correct chemistry (which works very well by the way) is a follows:
CaCl2 + 2 NH3 + H2O + CO2 ---> CaCO3 (s) + 2 NH4Cl
There is a famous name for this reaction when you substitute Sodium for Calcium, which I will let others expound upon.
Now on your 'complex' comment with NH3, I believe the dry salt CaCl2 (or even the dihydrate CaCl2.2H2O, for example) forms a series of adducts with
ammonia: CaCl2.NH3, CaCl2.2NH3, CaCl2.4NH3 and CaCl2.8NH3. The adducts may exist in an aqueous solution, but I do not believe they can be created in
an aqueous environment and speculate that they would not play a role in this reaction.
[Edited on 28-7-2012 by AJKOER]
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