Sulaiman
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How to push this reaction to the right ?
I bought calcium nitrate with the intention of making nitric acid using drain cleaner sulphuric acid,
the byproduct, calcium sulphate is no use to me, so I am considering HCl in the form of brick cleaner;
Ca(NO3)2 + 2HCl = CaCl2 + 2HNO3
How can I determine the equilibrium, and move it to the right ?
by Le Châtelier's principle, excess HCl would help
but I would expect recovery of products to be problematic,
is this possible, and practical?
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Velzee
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According to my notes;
The Equilibrium Constant(K)=(molarity of the products)/(molarity of the reactants)
And you've already know the first rule of Le Châtelier's Principle:
Rule #1—If you increase the amount of reactants, the amount of products shall also increase.
And:
Rule #2—Remove the products to get more of the products.
The way I'd suggest is to boil the solution to recover the HNO3, but this probably will be heavily contaminated with HCl. This will be a messy
reaction, indeed and probably not worth it. I suggest you use H2SO4 instead, as this would precipitate CaSO4 and leave HNO3 in the solution, but this
would leave quite a messy clean up in the reaction flask, but definitely a purer product if you distill the HNO3.
Ca(NO3)2 + H2SO4 ---> CaSO4 + 2HNO3
[Edited on 8/2/2016 by Velzee]
[Edited on 8/2/2016 by Velzee]
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DraconicAcid
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Quote: Originally posted by Velzee  |
If you choose your proposed method, I believe you should increase the temperature and boil the solution to shift the equilibrium to the right.
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That won't work, because HCl is more volatile than HNO3.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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zwt
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Both nitric and hydrochloric acid form azeotropes, and the hydrochloric acid azeotrope has a lower boiling point. Distilling a mixture of calcium
nitrate and concentrated hydrochloric acid will first yield wet hydrogen chloride gas, then azeotropic hydrochloric acid, possibly contaminated with
side products like nitrosyl chloride and, yes, traces of nitric acid.
You could add copper to your nitrate and hydrochloric acid mix, à la NurdRage, but the reaction is very inefficient, the acid produced heavily contaminated, and the calcium chloride byproduct contaminated with
copper and residual nitrate.
Alternatively, if sodium carbonate is cheaply available, you could make your nitric acid with sulfuric acid and calcium nitrate, boil the sulfate
byproduct with sodium carbonate solution to yield calcium carbonate and sodium sulfate, and react the calcium carbonate with hydrochloric acid to give
the desired calcium chloride.
[Edited on 2-8-2016 by zwt]
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Velzee
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Ah, okay, I edited my post to remove my error.
Check out the ScienceMadness Wiki: http://www.sciencemadness.org/smwiki/index.php/Main_Page
"All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident."
—Arthur Schopenhauer
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Richard3050
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I would also highly recommend using sulfuric acid. Even if the calcium chloride product is more interesting then the calcium sulfate it's much easier
to do. If you look online for videos about nitric acid synthesis almost always sulfuric is used. The boiling point of sulfuric is so much higher than
nitric that boiling the mixture will automatically push the reaction to the right and give you a nearly pure product. Check out a video by NileRed on
YouTube to use as an example.
"Science knowledge only adds to the excitement... I don't understand how it subtracts."
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PHILOU Zrealone
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1°) HCl is much stonger acid than HNO3, but is also more volatile.
2°) CaCl2 is quite soluble into water just like Ca(NO3)2 so precipitation is no help here to displace equilibrium.
3°) Traces HCl or CaCl2 with HNO3 arround will gas out O=N-Cl (nitrosyl chloride) and be a kind of aqua regia.
Thus not practical!
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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blogfast25
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| Quote: Originally posted by Richard3050 | | The boiling point of sulfuric is so much higher than nitric that boiling the mixture will automatically push the reaction to the right and give you a
nearly pure product. Check out a video by NileRed on YouTube to use as an example. |
That's largely irrelevant here. CaSO4 is poorly soluble, so that pushes the reaction to near completion. Then filter of the
CaSO4 hydrate and distil the filtrate.
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Sulaiman
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OK ... looks like the HCl option is not viable,
not a big surprise but I thought i'd ask anyway ... thanks.
H2SO4 + Ca(NO3)2 it will be.
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unionised
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Wow!
Nobody noticed?
HCl is a reducing agent; nitric acid is an oxidising agent and yet nobody saw the competing reaction as an possible issue?
HNO3 (aq) + 3 HCl (aq) → NOCl (g) + Cl2 (g) + 2 H2O (l)
et seq
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PHILOU Zrealone
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| Quote: Originally posted by unionised | Wow!
Nobody noticed?
HCl is a reducing agent; nitric acid is an oxidising agent and yet nobody saw the competing reaction as an possible issue?
HNO3 (aq) + 3 HCl (aq) → NOCl (g) + Cl2 (g) + 2 H2O (l)
et seq
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You must be tired...   
Read 1rst § of ZWT's post and the 3°) of my post above this post.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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unionised
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| Quote: Originally posted by PHILOU Zrealone | | Quote: Originally posted by unionised | Wow!
Nobody noticed?
HCl is a reducing agent; nitric acid is an oxidising agent and yet nobody saw the competing reaction as an possible issue?
HNO3 (aq) + 3 HCl (aq) → NOCl (g) + Cl2 (g) + 2 H2O (l)
et seq
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You must be tired...
Read 1rst § of ZWT's post and the 3°) of my post above this post. |
Yep; bed time.
However my point was that, under any circumstances where HNO3 might hope to be a meaningful product, decomposition as going to be a major problem. In
a "never mind traces- this won't work" sort of way.
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Magpie
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I would recommend filtering off that CaSO4 before distilling. The presence of all those solids might lead to some heavy bumping.
Use of a filter aid like diatomaceous earth (celite, etc) will help in the filtration of the slimey CaSO4.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Sulaiman
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magpie
so are you in effect saying that the reaction Ca(NO3)2 + H2SO4 => CaSO4 + 2HNO3
will run to the right without having to boill off the HNO3 ?
I'd prefer doing the reaction in a beaker, filtering and distilling
to having to get the calcium sulphate out of my one and only 500ml 24/28 flask.
(which is another reason I was considering HCl)
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Magpie
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| Quote: Originally posted by Sulaiman | so are you in effect saying that the reaction Ca(NO3)2 + H2SO4 => CaSO4 + 2HNO3
will run to the right without having to boill off the HNO3 ?
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Yes. When a precipitate is formed the reactants are taken out of the solution, driving it to the right. This is similar to generating a gas where
it escapes the reactor thus driving the reaction to the right.
I have never made HNO3 with Ca(NO3)2 but have made it several times with KNO3 and sulfuric acid per my procedure in prepublication. I don't see where
this will be much different except you will have to deal with that messy CaSO4.
The single most important condition for a successful synthesis is good mixing - Nicodem
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blogfast25
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| Quote: Originally posted by Sulaiman | so are you in effect saying that the reaction Ca(NO3)2 + H2SO4 => CaSO4 + 2HNO3
will run to the right without having to boill off the HNO3 ?
I'd prefer doing the reaction in a beaker, filtering and distilling
to having to get the calcium sulphate out of my one and only 500ml 24/28 flask.
(which is another reason I was considering HCl)
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Just rewrite the equation:
Ca(NO3)2(aq) + H2SO4(aq) => CaSO4(s) + 2HNO3(aq)
Clear now? Filter off the solids and you have an (impure) solution of HNO3. Distil and be damned.
[Edited on 3-8-2016 by blogfast25]
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Magpie
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I think it would be useful to take a look at my procedure for making phosphoric acid in prepublication. Note the voluminous amount of CaSO4 generated
and my comments about having enough water present.
Don't worry having too much water in the product distillate. You can always distill to the azeotrope (67% IIRC) and even to fuming nitric if that is
what you ultimately want.
The single most important condition for a successful synthesis is good mixing - Nicodem
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