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fatkangaroo
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calcium nitrate to ammonium nitrate
Looking for some help to do this reaction properly as I cant seem to get it right.
As I understand it the CN is dissolved into boiling water and the calcuim drops out as it won't dissolve in water.
Well I gave it a shot and the problem is everything dissolves and there are no solids to filter off. I boiled for ten minutes or so then put it in the
frezzer. Nothing is coming out full stop.
Any help would be appreciated.
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cyclonite4
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Problems with that method:
1. Ca(NO3)2 is quite soluble in water.
2. The Calcium wont just 'drop' out for no reason.
3. You lack the ammonium ion in all of your procedure.
What you should try is mixing with a stoichiometric amount of NH4OH with the Ca(NO3)2 to precipitate out Ca(OH)2, filter it off, and you will be left
with a NH4NO3 solution.
\"It is dangerous to be right, when your government is wrong.\" - Voltaire
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Jome
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That wont work either, ammonia is a base, but it is to weak to push Ca(OH)2 out of solution.
I tried it two months ago, and not even one tenth of calculated ammount Ca(OH)2 precipated.
To push Ca(OH)2 out of a solution of Ca-nitrate the base has to be stronger, it works fine with NaOH or KOH which I've used dozens of times.
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cyclonite4
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| Quote: | Originally posted by Jome
That wont work either, ammonia is a base, but it is to weak to push Ca(OH)2 out of solution.
I tried it two months ago, and not even one tenth of calculated ammount Ca(OH)2 precipated.
To push Ca(OH)2 out of a solution of Ca-nitrate the base has to be stronger, it works fine with NaOH or KOH which I've used dozens of times.
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I know. But with your method your not really forming AN are you now? 
Maybe try precipitating a less soluble calcium compound?
[Edited on 30-12-2004 by cyclonite4]
\"It is dangerous to be right, when your government is wrong.\" - Voltaire
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hodges
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How about mixing the calcium nitrate solution with ammonium sulfate? Calcium sulfate is insoluable so will precipitate out, leaving ammonium nitrate
solution.
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guy
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You can also mix regular ammonia with calcium nitrate to precipitate Ca(OH)2 and you end up with AN. Simple.
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FloridaAlchemist
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Hodges way should work fine
Calcium Nitrate and Ammonium Sulfate should work fine... The Calcium Sulfate is filtered off and the water is evaporated from the Ammonium Nitrate
solution at approx 105 'C in a oven.
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fatkangaroo
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Thanks everyone for your comments and assistance.
Just a little unsure how much of the Ammomium Sulfate should be added to the Calcium Nitrate solution?
I was wondering the same thing about the Ammonia-Calcium Nitrate technique.
I attemped adding the NaOH to the very cold solution that I still had from my first attempt. Nothing happened that I saw, but didnt really give it a
chance. I dumped it after about 1 hour.
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runlabrun
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Amounts of each reactant depends on the ratio:
Ca(NO3)2 + (NH4)2SO4 --> NH4NO3 + CaSO4
Equimolar amounts. Got it?
What do you mean about " was wondering the same thing about the Ammonia-Calcium Nitrate technique." You want to know how to go in the
reverse direction of what you have just done? ie Ammonium Nitrate --> Calcium Nitrate?
Adding NaOH to ammonium nitrate would have given you a solution of Sodium nitrate and ammonia in water solution.
You wouldnt have seen anything because both Ammonium and Sodium nitrates are soluble in water so the reaction would go unseen.
Best to mix a calcium compound of a weaker anion, the stronger Ca will attract the stronger anion (nitrate).
Acetate? You would do this:
NH4NO3 + Ca(C2H3O2)2 --> Ca(NO3)2 + NH4(C2H3O2)
-rlr
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fatkangaroo
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OK I am going to try the Calcuim Nitrate Ammonium Sulfate route and see how I go. What I really want to know is how much of the Ammonium Sulfate
shound be added per 100 grams of Calcuim Nitrate.
I am very new to Chemistry so I don't know how to work these things out for my self.
I am learning though and having lots of fun and the same time.Makes me wish I tried a bit harder at school,I am a late bloomer you see. My chemisty
adventure has only just begun and I feel so far behind the 8-ball compaired to everyone else on these boards.So please understand I am a bit slow on
the uptake.My lab is the poor mans kind-spagetti jars pyrex bowls and hotplate basic chemicals from open sources hardware ect.
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Magpie
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You are on the right track I believe. Calcium sulfate is insoluble and should precipitate out. You can then decant or filter off the ammonium nitrate
solution. But if you don't get the stoichiometry right you will have ammonium sulfate or calcium nitrate in your product as contaminant.
Write a balanced chemical reaction. Determine your molecular weights. Multiply the molecular weights times the corresponding coefficients in the
reaction. The results will allow you to calculate the weight of ammonium sulftate needed per gram (or kg) of calcium nitrate used. If you don't
understand any of this go to your public library and check out a text on elementary chemistry. Let us know how this works out. Where do you get the
calcium nitrate and ammonium sulfate? - fertilizers?
The single most important condition for a successful synthesis is good mixing - Nicodem
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fatkangaroo
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Ahhh. I see... fun fun fun.
Yes indeed my Cacium Nitrate and Ammonium Sulfate are both fertilizers.
Found the molecular weights, just doing a online stoichiometry lesson at the moment. I know it will take me some time to fully understand all the
concepts.I have really have to get my own books.Downloaded Vogels but I find it very hard to read as the writting is very small and faded.
I think for today I will give it a try without knowing the bananced reaction.
The plan is to make the hot Calcuim Nitrate solution then slowly add the Ammonium Sulfate spoonful by spoonfull untill I see the Calcuim Sulfate
appear and take it from there.
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neutrino
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Don’t you mean add sulfate until CaSO<sub>4</sub> <i>stops</i> precipitating? You really should go with accurately weighed
masses, though.
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runlabrun
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Yeah neutrino is right, you should add till it stops precipitating. But accuracy with amounts is advisiable, you dont want to end up with an excess of
the equally soluble ammonium sulphate in your solution.
You should come up with 80.6g Ammonium sulphate to treat 100g of Calcium Nitrate.
Make the solution of 100g calcium nitrate in just enough water (138g Calcium nitrate is soluble in 100mL of water) to dissolve the solid so this means
around about 72.5mL. Slowly add the 80.6g ammonium sulphate in small portions stirring in between each addition. You will see calcium sulphate
precipitating out, being 0.21g per 100mL it isnt very soluble at all. Filter out the precipitate and collect the fluid, this is your ammonium nitrate
in solution.
Sound good? Easy?
-rlr
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fatkangaroo
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Happy days
I really feel indebted to you guys!
For me the success of this experiment will be a major steping stone and I feel good.Can't wait to get started.
Thanks runlabrun for spelling it out for me clear and simple.
Still going to hit the books and learn to work things out for myself and hopefully be able to contribute to the board and one day be able to help
someone else.
Let you know tommorow how things went.
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fatkangaroo
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Just finished trying to make the Ammonium Nitrate and had no luck, hoping for another point in the right direction.
First I added 100 grams of Calcuim Nitrate to 75ml of distilled boiling water this all dissoved quickly and the mix started to get cloudy.Next I
added the 80 grams of Ammonium Sulfate slowly over around 20 minutes and the mix looked like milk.I was a little confused at this point as I could not
tell what was the Calcuim Sulfate precipitating and what was undissolved Ammonium Sulfate.Anyway the mix was very thick and filtering came next.A
large amount of chalky stuff was collected and thrown away. I put half the solution into the frezzer and so far nothing has happened. The other half
of solution was put into the oven at 105 'c. It boiled down into a brown sludge which looked nothing like beautiful crystals I was hoping for.
Any suggestions?
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runlabrun
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The mix started to get cloudy when it was just calcium nitrate in water? Maybe i was a little off on the solubility could try to add a bit more water,
20-30mL or so.
Your mix after the addition of ammonium sulphate looked like milk, that should be good, CaSO4 is a white precipitate, leaving the mixture to settle
and cool (place it in the fridge) should allow you to achieve a white sediment.
Very thick? Example? It would be thick while the water is still hot and the precipitate is floating around, allow to form a sediment as mentioned
above.
Chalky filtrate would be the calcium sulphate and any undissolved crap. Putting the fluid into the freezer wont do much as ammonium nitrate is very
soluble (208g per 100mL 25oC water) so you wont see anything.
However i am interested in your brown sludge.... no idea what that would be.... maybe some contaminants in your original reagents.... where were they
from? The reaction would work with some gentle heating and quality reagents.
The product may have contamination so re-x from alcohol to see if you can leave some of the crap behind.
-rlr
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neutrino
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A word of advice: whenever you’re going to do a precipitation reaction like this which produces large amounts of precipitate, add a
<b>very</b> large excess of water unless you want a large gel-like cake of precipitate.
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Magpie
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brown sludge
You should not have any precipitate until you start adding the ammonium sulfate. If you do you didn't have enough water initially.
There should be no need for heating or freezing.
Remember that you are working with fertilizer grade not reagent grade material. There's a reason why the former is cheap and the latter is
expensive - i.e., purity. That doesn't mean you can't eventually purify your ammonium nitrate with proper procedures, however. Your sludge
is probably most ammonium nitrate. 
The single most important condition for a successful synthesis is good mixing - Nicodem
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guy
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The brown sludge is probably partially hydrated calcium sulfate known as Paster of Paris.
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neutrino
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Plaster would be a white gel-ish precipitate. Come to think of it, I do remember a small amount of brown goo when I was boiling down ammonium nitrate
from cold packs. Might it be a decomposition product of some sort?
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The_Davster
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Maybe the decomposition product of some additive... The decomposition products of ammonium nitrate are all gaseous.
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runlabrun
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"Yes indeed my Cacium Nitrate and Ammonium Sulfate are both fertilizers. " -fatkangaroo
I think this is the problem, depending on what % CN and AS are in the mix and what else is there....
Sorry bout the water volume issue, i thought the mix would sediment rather easily in the fridge, obviously it was incorrect, so as neutrino said, use
large volume of water.
What has been assumed is all i can think of, purification of starting materials would be my best idea for a resolution to the problems your having.
-rlr
[Edited on 5-1-2005 by runlabrun]
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fatkangaroo
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If first you don't suceed try try again.
Gave It another try after reading your comments and doing a bit searching around for answers.
I followed the same procedure as last time accept I used 150ml of boiling water.The hot solution got very thick and I filtered it quickly. This is
because as soon as stirring is stopped it thickens immediatly even if the solution is cooled,and not just thick its just about a solid.Anyhow I put
the soultion into fridge and with in 10 minutes there was another layer of chalk to filter off. Once that was done I was left with a clear water
looking solution This time I put the solution on a hot water bath and slowly
evapourated and water out. To my absolute joy small white crystals started forming and a couple of long needle like ones to.
As for the brown sludge from yesterday, I started looking for some answers. I found a archived thread from another board. The thought there was AN
when heated in solution can go straight from the liquid to molten AN without you knowing it.I think now this may have happened to me.I put a small
sample into water and it got cold like AN should do. Now I have to find the best solvent to recrystallize in.
So all in all I am pretty happy the way things are going although I'm not 100% sure what I have is AN. I have plenty of Calcium Nitrate and
Ammonium Sulfate so I'm just going to keep on going to I get it as perfect as I can get it.
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fatkangaroo
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Just finshed another few batches.
I can say that the amount of water does not seem to have any influence on the mix. Large or small, the mix will still turn thick.
I use old sheets for filters and everytime I filter this mix it clogs up in seconds and the solution has to be squeezed out drop by drop.
I bought a instant cold pack to do some comparisions between the homemade stuff the commercial product. The main difference is the homemade product
will not turn to crystals in the freezer while the ice pack AN loves it. Why is that? Also the shapes of the crystals vary greatly. I mean the cold
pack AN forms beauitiful long clear needles, while the homemade gets tiny little white ones with the odd big one.
I have tried a few different ways of precipitating the homemade AN. Tried the oven again, this time on 75'c this mix is still going even now. It
has been in there for around 25 mins there is a crystal like skin forming on the surface with a few crystals stuck to the sides and bottom. Next I
tried the electric fry pan set on 110'c. Unfortunatlely it went molten. I was watching it wondering when it was going to happen. So I dumped what
was left (not much) onto a dinner plate. The second the hot solution hit the plate it turned into a solid that ran all over the plate and left what
looked like icing suger. Did again on the electric fry pan and let it boil right down then turned the heat off(molten again). As it cooled it formed a
thin cake across the pan. This was a major pain to get off, got it done but scratched the crap out of the pan.The AN was very dirty from the cooking
surface of the pan.
Any thoughts on what I could do to make this process more effective or anything you can see that Im doing wrong.
Just pulled the latest batch that was in the oven on 75'C. This is the best temperature for me. No molten crap straight to white powder with a 50
gram yield. Is this good or bad?
[Edited on 6-1-2005 by fatkangaroo]
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