Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: P-man on June 23, 2005, 04:14:23 PM
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Alright, I did this yesterday, but I need your help, (or advice).
1) I dissolved some ammonium chloride (NH4Cl). This gave me an acidic solution. NH4Cl + H2O --> ?NH6ClO?
2) I then added some sodium carbonate to the acidic solution to form a salt. NH6 + NaCO3 --> Na(OH)2 + H2O + NH2C + ClO
Please correct as you wish.
Pierre.
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1) the ammonium chloride dissociates in water to form HCl and NH3. since HCl is a stronger acid while aq. NH3 is a weak base, the solution is generally acidic. water acts as a solvent.
2) the Na2CO3 reacts with the acid i think to form NaCl + H2O + CO2
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I would imagine that you have a slightly more complicated reaction going on. Ammonia in water is at equilibrium:
NH3 + H2O <--> NH4OH
When you initially dissolve ammonium chloride in water, you should get:
NH4+ + Cl-
Now, since chloride is the anion of HCl, it won't try to form HCl right away. However, you may wind up with a small amount of this reaction:
NH4+ <--> NH3 + H+
Because this is in equilibrium, some acidic protons will be in solution. That leaves both H+ and Cl- in solution, or aqueous HCl. This is some speculation on my part, and it may be something a little different than that.
xiankai is correct with his assertion about how sodium carbonate will react with an acid. If you did not notice any gas evolution, though, you may have had this reaction:
2 NH4+ + CO3-2 --> (NH4)2CO3
IIRC, ammonium carbonate stinks pretty badly, so if you are able to isolate the salt, see if it smells like ammonia at all.
Also, when you write NH6, take a look at the structure. What does the Lewis dot structure tell you about that formula?
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However, you may wind up with a small amount of this reaction:
NH4+ <--> NH3 + H+
Because this is in equilibrium, some acidic protons will be in solution.
http://www.chembuddy.com/?left=pH-calculation-questions&right=pH-weak-base-hydrolisis-q1 (http://www.chembuddy.com/?left=pH-calculation-questions&right=pH-weak-base-hydrolisis-q1)
The only difference is that pKb for NH4+ is 9.25.
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It smelt like Windex.
So you mean I seperated the Cl and the NH4? Wow.
And then I made Hydrogen? Awesome...
But then the H and the Cl form aqueous HCl... makes sense.
Thanks...
Pierre
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NH4Cl when dissolved dissociates into ions, as hmx9123 wrote.
You haven't made hydrogen. Hydrogen and H+ are two different things.
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Oh, ok, Thanks.
But check this one out.
H2SO4 + NH4Cl --> SO4 + HCl + NH6
Proof for SO4: Heavy sulphuric fumes came out of the est tube. It smelt terrible. Another option could be SO2.
Proof for HCl: I had a liquid that measured a pH of about 1 or 2.
Proof for NH6: Well, that's all the reactants that were left.
Is that correct? My proofs seemed convincing enough for myself, but are they for you?
Pierre
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I am afraid you don't understand a thing.
6 H2O -> H12O6
As good as NH6
Your proofs doesn't prove anything :(
Proof 1: there is no such thing like SO4. SO2 - and why not SO3?
Proof 2: you have used sulfuric acid, why do you expect pH to be forced by HCl, if the solution was acididc from the start?
Proof 3: there is no such thing like NH6. Just because you can write formula doesn't mean it describes any compound.
As they tell "a day in the library can spare you six months in the lab". They also say "six months in the lab can spare you a day in library". It is up to you to select which way you wanna go.
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I would imagine that you have a slightly more complicated reaction going on. Ammonia in water is at equilibrium:
NH3 + H2O <--> NH4OH
When you initially dissolve ammonium chloride in water, you should get:
NH4+ + Cl-
Now, since chloride is the anion of HCl, it won't try to form HCl right away. However, you may wind up with a small amount of this reaction:
NH4+ <--> NH3 + H+
Because this is in equilibrium, some acidic protons will be in solution. That leaves both H+ and Cl- in solution, or aqueous HCl. This is some speculation on my part, and it may be something a little different than that.
xiankai is correct with his assertion about how sodium carbonate will react with an acid. If you did not notice any gas evolution, though, you may have had this reaction:
2 NH4+ + CO3-2 --> (NH4)2CO3
IIRC, ammonium carbonate stinks pretty badly, so if you are able to isolate the salt, see if it smells like ammonia at all.
Also, when you write NH6, take a look at the structure. What does the Lewis dot structure tell you about that formula?
Well, NH4OH really doesn't exist. It's more appropriate to write it out as hydrated ammonia (NH3*H2O). The NH4+ ion will, however, form some H+ in solution which is why ammonium salt solutions are acidic in nature. Ammonia solutions are basic because the ammonia molecule will pull off some Hydrogen atoms from water and form NH4+ and some free OH- ions. The ability for NH3 to form NH4+ and free OH- ions is a bit greater than NH4+'s ability to donate it's H+ and form free ammonia again. Hence why NH3(aq) is basic in nature.
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Oh, ok, Thanks.
But check this one out.
H2SO4 + NH4Cl --> SO4 + HCl + NH6
Proof for SO4: Heavy sulphuric fumes came out of the est tube. It smelt terrible. Another option could be SO2.
Proof for HCl: I had a liquid that measured a pH of about 1 or 2.
Proof for NH6: Well, that's all the reactants that were left.
Is that correct? My proofs seemed convincing enough for myself, but are they for you?
Pierre
I agree with Borek. Please study some basic chemistry books and try to really understand what is going on.
When you add H2SO4 to NH4Cl, then the following reaction occurs:
NH4Cl + H2SO4 --> NH4HSO4 + HCl
With some heating you probably can go further:
2NH4Cl + H2SO4 --> (NH4)2SO4 + 2HCl
The 'heavy sulphuric fumes' you get do not contain any sulphur. This is the HCl, which escapes from the test tube as colorless gas. With humidity in the air, it forms a white fume, which consists of very small droplets of water, with a lot of HCl dissolved in it (in fact, the fume is hydrochloric acid, a.k.a. muriatic acid).
The same experiment can be done with plain table salt:
NaCl + H2SO4 --> NaHSO4 + HCl
Just do the experiment and you'll have a very similar result.
If you heat the mix of NH4Cl and H2SO4 very strongly, then you _might_ get some SO3, but before you get that, you have to heat really strongly (a few hundreds degrees centigrade), so it is unlikely that the fumes you obtained contain any SO3.
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So I DID make HCl, didn't I? I just got everythng else wrong, right?
So, what I have learned...
NH6 doesn't exist as a seperate compound.
SO4 doesn't exist as a seperate compound.
Nor does SO2 exist as a seperate compound.
Now, some questions:
Why can't these coumpounds exist?
How is H+ not the same as Hydrogen?
What are some books that I should read?
Thanks for all your trouble in your helpless attemps to make me understand,
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So I DID make HCl, didn't I? I just got everythng else wrong, right?
Yes.
SO4 doesn't exist as a seperate compound.
There exists SO42- - product of sulfuric acid dissociation.
Nor does SO2 exist as a seperate compound.
SO2 exists, as well as SO3.
Why can't these coumpounds exist?
That's what chemistry is about :)
How is H+ not the same as Hydrogen?
H+ is an ion. Hydrogen exists in the molecular form H2. They have completely different properties.
What are some books that I should read?
Somebody else must answer, I can propose you a bunch of books in Polish ;)
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Have you taken high school chemistry? It seems that most of what we covered back then would give you a solid foundation for this type of stuff.
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Read this thread, the first post specifically:
http://www.chemicalforums.com/index.php?board=2;action=display;threadid=2402
I would get the Pauling book if I were you. You should be able to order it locally so you don't have to pay outrageous shipping, it is cheap, and though it is somewhat old, it is well-written and the concepts that you need to learn haven't changed much since the book was written. You could get a more updated textbook, but because the information you need is so basic and the price of this book is so cheap, I would go with it.
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Read this thread, the first post specifically:
http://www.chemicalforums.com/index.php?board=2;action=display;threadid=2402
I would get the Pauling book if I were you. You should be able to order it locally so you don't have to pay outrageous shipping, it is cheap, and though it is somewhat old, it is well-written and the concepts that you need to learn haven't changed much since the book was written. You could get a more updated textbook, but because the information you need is so basic and the price of this book is so cheap, I would go with it.
I doubt whether this book is suitable. I also have this book and I really like it as one of my best chemistry books, but I'm afraid the level is too high. If I judge the original posts from P-man, then I would suggest to buy a book for high schools, starting with the real basics of chemistry (e.g. the concept of atoms, molecules, formula's, simple forms of bonds etc.). Things like wave functions, orbitals, hybridization etc. are way beyond the level the original poster needs.
I write this, not to piss off P-man, but to prevent having him disappointed. All of us have to start with the real basics. A good highschool book also may have some nice simple experiments, with explanations, which may help him further.
Unfortunately I cannot suggest any title of a highschool book (I'm from the Netherlands), so someone from the US or Canada may help further with this.
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I think alot of my high school science books were Addison Wesley, or Nelson (I live in Canada).
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I had two HS texts in two different chemistry classes. One was Addison-Wesley, and I thought it sucked. It dumbed down the chemistry to the point where it made no sense half the time and in some cases, it was just plain wrong. My second book was a first year college chemistry book that served its purposes very nicely. You certainly don't have to waste your time with wave functions when you first start out, but that can easily be skipped in the Pauling book. I'd rather suggest specific chapters of the Pauling book to read than to suggest a poorly-written HS book. If you have a good HS book, then fine. Otherwise, I'd start out with a General Chemistry college text. I suggested Pauling because it was cheap. Of course, I bought my Zumdahl text for $2 used, so that was cheaper.
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I just finished Grade 7, arnyk. I just got this book called The Golden Book of Chemistry Experiments. I think it talks about the basics. Otherwise, I have the Firefly Science Encyclopedia. It's great. I'm learning lots of stuff from it. It's just when you guys are talking, sometimes it's a little complicated. But I mostly get the big picture.
I'm trying to learn more over the summer and next year so I can have a head start in High School.
P.S. I'm leaving on Thursday for camp. I'll be away for a month, away from the internet, so don't expect me to reply. I'll be reading tons on chemistry, though.
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If you're only in 7th grade, you should have no problems with things when you get there. For a 7th grader, you understand a lot; for a 35 year old, you could use some work. :) You'll probably have a great time with chemistry when you get to high school. Good luck!