NH3 Boiling Point

Beautiful!

That PDF is Perfect!

Thank You!

Joe

Mixing water & ammonia could result to a solution both containing the 4 compound below each with a distinctive property. Stability of each compound is dictated by temperature(saturation).

NH₃ + H₂O NH₄⁺ + OH⁻ (compound)

Looking at the equation above one would expect from this equation that as NH3 decreases->NH4 increased conversely exactly the same way, NH4 decreases as NH3 increases.

NH4 & NH3 has distinct saturation temperature, NH3 having a lesser molecules of H will be lighter than NH4 (basic chem).

Looking again from the equation above, NH3 can not just boil like

CO2 + H2O = CO2 + H2O carbonated water (mixture)

well, it is because obviously....you answer

OK,

Now looking at that pdf

http://www.airgasspecialtyproducts.com/Libraries/Aqua_Ammonia_Technical_Data_Manual/Physical_Properties.sflb.ashx

If i had a concentration of HN3 25% and H2O 75%

It looks like if I raised it to 95 or higher the NH3 would boil off right but none of the H20 as long as I stayed below 212 yes?

So Like if I raised it to 150 to 175 deg or so all that would be boiling off would be NH3 yes?

Joe

Actually, no.

At all temperatures there would be apartial presure due to NH3 and a partial pressure due to H2O with the total pressure equal to the atmospheric condition over the liquid. The ratio of those partial pressures would tell you the concentration of NH3 in the vapor. The rate of total evporation would tell you the amount of NH3 say in pounds per hour coming out of the solution and that would depend on how much heat was being put into the system.

A key part of this post is the term "partial pressure". Water turns into vapor at nearly any temperature- as does the NH3/NH4. Water evaporates even when it it ice in a freezer. It definitely does not need to be 212F to vaporize, and- even if it it 212F, the rate of vaporization is determined by the additional thermal input available for the phase change.

A good question though that I think you should also answer is, "can all the NH4+OH be converted all to NH3?" Just to make the readers have a clear grasp in equilibrium of solution.

NH₃ + H₂O NH₄⁺ + OH⁻.

Since the NH3 will leave the system as a gas the equilibrium will continue to drive the reaction to make more NH3 until for practical purposes it is all gone. It may take a long time for it to get to that point, but it will eventiually get there.

You can smell the ammonia when a bottle of the stuff is opened. Therefore there must be ammonia molecules in the air. Hence it do boils off the solution.

Even solutions of ammonia in water above "household" strength need to be stored in pressure vessels (although the pressure is not great). The typical strength of solution being used for NOx control in the power industry is now 20% or slightly less due to restrictions placed on higher concentrations (i.e. 25%) by the EPA in an effort to reduce "fugitive emissions". Obviously, dissolving ammonia in water, there is a much different "boiling point", and one considers the range of vapor pressure that exists across the range of storage temperature. Tanks should be painted in such a way as to not have much solar gain.

Actually I may be chasing an idea that won't work anyway. And maybe some of you can help me with this.

OK, we all know the boiling point of NH3, and hence the condensing point would be the same.

I do a LOT of high altitude Ballooning. Been doing it for well over 22 years now. Some of you are familiar with our projects, Like how about the view from over 100,000 feet,

Of a flight we did for several hundred Boy Scouts, here is a you tune video of that flight,

http://www.youtube.com/watch?v=HJ0IT4ZwtSo

But a long duration flight so far has been something we have always wanted to try.

There are many ways to do this but most are very expensive too. But one we thought of trying is to use NH3 as the lifting gas. It is lihter than air, It has the lifting capacity of about 60% of H2 so not good but not too bad either, BUT it does have one property, it's boiling/condensing point is in the range of temps that we fly in.

we can fill the balloon with 100% NH3 and launch it, and it will rise till it gets to the level where it's cold enough to condence out and of course then it would start to fall only to hit warmer air and re vaporize and regain it's lift it should continue bobbing back and forth.

But then we got the thought of a Hybrid. fill the balloon with 75% of the needed lifting power required of H2, then add the remainder needed with NH3.

This way we use much less of the NH3 and the same effect would happen true?

Once it gets cold enough to condence the NH3 it would and then the balloon would start to come down only to warm up some again, and here we go a bobbing.

OK Now the question is, will that happen? Or will the H2 and NH3 mix into some other hybrid compound and the NH3 no longer condense where it should at the temp it should?

If using H2 messes this idea up how about a hybrid HE and NH3?

Joe

I think NH3 would not be a very good material to inflate baloons for several reasons, as you already mentioned. But also, remember NH3 is a flammable gas. It similar disadvantage that way as does H2, not as explosive, but still very capable of having an explosion. Better to stay with helium or hot air if that is the type of baloon you fly.

Not a Problem We have been using H2 for 22 years on these flights, we have already done over 50 of them. It's not a problem at all so the flammability aspect is of no concern.

Thanks for worrying about us tho.

In addition the world supply of HE is running out as we speak. and unlike H2 there is no way to make any more. Once it's gone, it's gone forever,

The national weather service which launches well over 110 balloons like this twice a day soo 220 balloons a day every day has also switched over to H2 because of the dwindling supply of HE

Very interesting, re. use of H2 in baloons. I thought that ended with the Hindenberg. Just goes to show how out of touch I am. I still think using H2 is playing with fire, (no pun intended). It seems like there is a lot of "crude" helium available at a relatively low price. That is a mixture with nitrogen at around 80%. That would have plenty of lifting power and be inert. Wouldn't that make more sense?

Here's a link to some info. World reserves are actually very large so there is really not a "shortage" considering uses of it in its less pure form.

http://minerals.usgs.gov/minerals/pubs/commodity/helium/mcs-2009-heliu.pdf

But in these "LESS PURE" mixes, the performance is terrible.

Yes there are some other groups now doing what I do, and always run HE, I always run H2, And with identical payloads where I'll hit 115,000 feet, they with GOOD HE, they rarely get over 100K and using "Party" balloon HE the mix as you suggest they usually only hit 75K or so.

Never mind the cost too!

A GOOD quality HE tank is now going for over 100 bucks, where I can get the same amount of H2 for 19 bucks.

Just one more comment on the safety item. I have worked with hydrogen on industrial scale for many years, in gas and liquid sytems at various pressure levels from low to relatively high pressure. I know it can be handled safely, but I have always had a healthy respect for it.

Perhaps it goes back to a demonstration given during a freshman chemistry lecture session (many years ago) where the very learned professor wished to impress the students about the explosive power of hydrogen. He filled a ballon to about a six inch sphere with hydrogen and set it off in the lecture hall. It gave a shock wave enough for everyone to feel it and duck. I will always remember the dust flying out from the cracks in the floor in that old, fairly large, lecture hall.

One of the hazards is that its explosive range is very wide, and the energy level needed to ignite it is very low. The saving grace is that since the gas is so light it diffuses out into the atmosphere quickly and gets diluted, but still I would suggest anyone using it to do so with much caution.

He had to have a mixture of H2 and O2 in that balloon. H2 all by itself will not burn, and never ever explode. It MUST have oxygen "MIXED" in with it.

It will Burn yes but only if it has O2 MIXED in with it. to be explosive.

We have on probably 50% of the flights when we were waiting for the chase and recovery crews to come back in the evening, once it gets dark we would fill large trash bags with the H2, then tie onto it a ohhh say 100 foot long piece of knitting yarn that has bbeen soaked in either diesel fule or charcoal lighter fuel. we'd let it out till we are just holding the bottom of the string light it and let it go, It would get ohh 2 or 3 hundred feet up and it would hit the bag and there would be this orange fireball. but NO explosion, more or less a fireball the same size ad the trash bag.

But then to prove the point we'd then do the exact same thing but have the bag already filled with about 1/2 way with air. and do the same thing,

and then yes there was a large explosion.

H2 has a bad wrap from the hindenburg, plus it was determined it never exploded anyway it more or less Burned as i described earlier and then the fabric covering thatwas highly flammable it was made 90% of the flames. but there were no explosions anyway.

Just a comment, maybe off topic, but safe handling of hydrogen is something I have been concerned with for many years so I would like to comment on your post.

Unless you fill the container, whether it is a balloon or anything else, with the hydrogen starting from a completely empty vessel, i.e. near "full vacuum" or a vessel charged fully with an inert gas such as nitrogen, you will have an explosive mixture in the vessel during the filling. Also, depending on what pressure you go to, you can end up with an explosive mixture at the end of the filling. The lower explosive range is about 2%, upper is around 70%. The professor just filled the balloon starting from air in the balloon, so of course there was an explosive mixture.

Certainly pure hydrogen in a closed system will not burn. It is stored in tubes and tanks all the time without burning. But any leak can be ignited by any spark. If the leak is into a confined area any spark can set it off explosively.

Pure anhydrous NH3 might work, as well as your hybrid idea, The H2 and NH3 will not react. However, there are several concerns, including chemical compatibility with the balloon. My biggest concern would be that the NH3 will cause the balloon to absorb a lot of moisture from the air. I won't go into a lot of detail, but this is likely with anhydrous NH3.

Once there is moisture in the balloon, you are dealing with a complicated 3 component system. Once it gets cold enough, NH4OH or H2O will condense (at a much higher temp. than anhydrous NH3). If there is sufficient moisture, the condensed water can actually suck all the gaseous NH3 out of the balloon, pulling it into solution.

So, maybe it would work, but I would guess it would be very unstable.

I infer that you were hoping to use NH4OH because it is easier to handle, then simply heat it to get NH3. This would be a very bad situation, as the balloon would contain NH3 saturated with water. I question whether it would have any lifting power at all, and it would collapse as soon as the temperature dropped a few degrees.

Thank you, Thoughts mixed below,

Pure anhydrous NH3 might work, as well as your hybrid idea, The H2 and NH3 will not react. However, there are several concerns, including chemical compatibility with the balloon.

That we won't know I guess till we try it too. It's a special formulation of a Latex / syntheitic blend.

My biggest concern would be that the NH3 will cause the balloon to absorb a lot of moisture from the air. I won't go into a lot of detail, but this is likely with anhydrous NH3.

The balloon is totally void of air or any other gasses till we put the lifting gas in the balloon, even then it is still only whatever gasses we put into it.

Once there is moisture in the balloon, you are dealing with a complicated 3 component system. Once it gets cold enough, NH4OH or H2O will condense (at a much higher temp. than anhydrous NH3). If there is sufficient moisture, the condensed water can actually suck all the gaseous NH3 out of the balloon, pulling it into solution.

Now if we are sure to use anhydrous NH3, this should not be a concern correct?

So, maybe it would work, but I would guess it would be very unstable.

I infer that you were hoping to use NH4OH because it is easier to handle, then simply heat it to get NH3. This would be a very bad situation, as the balloon would contain NH3 saturated with water. I question whether it would have any lifting power at all, and it would collapse as soon as the temperature dropped a few degrees.

Yeah I was also thinking of that. The reason was hoping to distill the NH3 out of the mix.

Reason? Getting Pure anhydrous NH3 is dirt cheap! Farmers around here use it all the time to use it as a fertilizer. in the next few months I'll be seeing 500 to 1000 gallon tanks rolling down the highways and out in the farmers fields. BUT try to get just a few gallons is as easy as buying a few grams of cocaine.

NH3 is used in the process of making Meth. so anyone that is looking for just a small amount is a suspect all the time. Buy a 1000 gallons and it will be delivered to your door. But want to get a gallon or two and it's like wow.

Joe

Why not use methane hydrogen, just as easy, no concerns over materials compatibility, or just use methane, since it is not so likely to condense to a liquid in flight. Then I won't have to tell you how exactly to purify and obtain pure anhydrous ammonia in small quantities. Suggestion: absorb the water vapor.

If transporting the methane under pressure bothers you, it should not. Just make sure you follow all the supplier/manufacturer safety guidelines related to transporting the pressurized bottles, and you should be (1) legal, and (2) safe.

Comments below,

Why not use methane hydrogen, just as easy, no concerns over materials compatibility, or just use methane, since it is not so likely to condense to a liquid in flight.

But see that is what we want it to do. Is condense so we loose the lift, and it starts to come down then it warms up and we regain the lift, then it cools, etc. eventually it would somewhat hover at a certain altitude with a small amount phase changing back and forth.

Joe

OK, I missed the context underlying your original question and made comments dealing with simple chemical principles regarding NH4OH solution properties as a bulk fluid. While the comments were ok from chemistry theory, they likely did not address your need very well.

I see now that you have a very particular objective. Namely, find a fluid that on warming in the liquid phase will generate a gas, lighter than air, the gas to be used for lifting a balloon. The process must be reversable such that on cooling the gas will be reabsorbed back into the liquid phase reducing the amount available for the lift. The cycle must be capable of being repeated and safely regulated to provide a desired amount of lift. Can this process be implemented using NH3 in aqueos solution?

Very interesting question, and I think quite an innovative concept for inflating and deflating a balloon. I have absolutely no idea on whether it could be made to work or not. As an aside I would say that maybe the concept has been explored by someone before, almost everything has, and a literature search may provide some insight. It may have been tried with something other than ammonia.

As a general observation without giving it a lot of thought my first impression is that the limitation may come more from mechanics rather than chemistry. It seems to me you will need some hardware to make the process function, i.e. heating, cooling, reabsorbing, etc. and that together with the weight contributed by the liquid NH4OH solution and its storage vessel would over burden the whole thing so that it would never fly, or make the size of the balloon so large it was not a practical thing. That's just a guess, but it would certainly be nice to see it work.

Thoughts below,

As a general observation without giving it a lot of thought my first impression is that the limitation may come more from mechanics rather than chemistry. It seems to me you will need some hardware to make the process function, i.e. heating, cooling, reabsorbing, etc. and that together with the weight contributed by the liquid NH4OH solution and its storage vessel would over burden the whole thing so that it would never fly, or make the size of the balloon so large it was not a practical thing. That's just a guess, but it would certainly be nice to see it work.

Actually None of the above is needed. the earths atmosphere does it all for us,

we put the needed amount in the balloon on the ground in gas form to get the desired lift.

seal off the balloon, and launch it.

it gets higher and higher and colder and colder, (parts of a typical flight can experience -70 below temps!)

It gets to a zone whereit's now cold enough to start condensing back to a liquid. and it does, the liquid just collects at the bottom of the balloon, eventually enough condenses and nthe amount in gas for is too little to provide enough lift and it starts to come down, but in doing that it finds warmer temperatures and the liquid then changes back to a gas and providing enough lift

bla bla bla..

Joe

Sounds like you are thinking ammonia gas, not NH4OH aqueos solution properties.

Would you give us some idea of the dimensions of the balloon. When fully inflated what is the approximate volume and what gas pressure do you need to maintain inside the balloon to keep it inflated from minimum to maximum size for the various altitudes you want to operate within?

Need to look at liquidus curve temp-pressure relationship for methane, but I think this is a cryogenic liquid, and -70 F is considerably above the normal boiling point. Interestingly enough, propane, or even butane might fit in here, except one small problem, I think the vapors are denser than air. How about using methane in solution of butane? Temperature should have a role in the fraction in vapor and in solution.

A balloon is like a large membrane. While it is meant to keep H2 in, in reality H2 will permeate out to some extent, and gases in the surrounding air permeate in.

With a gas like H2, this effect is probably pretty small. Some moisture will permeate in, but the effect is probably minor.

Ammonia, however, has a very high affinity for water. Even if the gases are perfectly dry, it may be that the NH3 would pull moisture through the balloon walls. I don't know this will be a major effect, but it is something I would be concerned about. It would be an interesting experiment.

Of course, where this is going there isn't a lot of moisture left in the atmosphere too, true?

Joe

It seems my concern is unfounded, and NH3 is used in weather balloons.

Good luck, and let us know how you make out!

There's not a Good Question so I give you a GA, this could be ground breaking work, for sure a great project for you NSS people, keep us posted Joe.

Since the balloon of which you speak travels up and down, how rapidly, and how far? If the balloon could be made on a tether, then the winding out of the tether could be made to turn a generator? How about some sort of hydraulic re-wind mechanism that would from energy stored during spool out?

I think your concept has merit, and I would use ammonia anhydrous with the hydrogen, just to avoid any problem with water forming ice or condensing, etc.

This whole process resembles an ammonia/water absorption refrigeration cycle, perhaps best described as a back-and-forth rather than a circular process. I am inclined to think that it would work, but I haven't traced out a water/ammonia chart for the whole process. In any case, this has certainly become an interesting topic.

Yup it i interesting,

If anyone wants to be on a list, I can notify them when we will be launching. I usually have a live streaming video , chat rooms,, ytackers,, etc. so people on the web can join in.

Joe

The thing is that ammonia condenses at -33 C if the pressure is maintained at atmospheric pressure, if the pressure in the balloon goes lower, as it rises, the pressure in it goes lower and the condensing temperature goes lower too. I don't think that ammonia will condense inside the balloon. What you have to put up is the smell, which at 100 parts per million makes the place unbearable. The latex, if resists to ammonia it suppose to make a sound vapor barrier. First, see if you can withstand the smell, after that, put some ammonia with water in a bag made out of your balloon fabric to see if it resist to chemical action (is caustic). But most important is the smell, small leaks make you run away.

I believe that is the analogous cycle that would be at work in this. It is what I thought he was describing, but his last comment relates better to a system in which pure NH3 gas would fill the balloon.

The thermodynamic properties for aqua ammonia are published and available to do an analysis of what it would take to make it work if that were the media. But, I wonder about the dynamics and mechanics of it in terms of the amount of NH3 that needs to be released from solution and reabsorbed to give the balloon the type of inflation it needs to be aloft at various altitudes; i.e. how much aqueos NH4OH to do you need and how much heat transfer you need to do the phase changes. How would this work relying strictly on ambient atmospheric conditions to do all the work?

If it is anhydrous NH3 it is a different analysis.

Interesting discussion with some high quality comments.

I have only a couple minor items to add.

If you intend to use ammonia to regulate height consider that ammonia has a relatively high specific heat....over twice that of air. Depending on the heat transfer characteristics of the balloon, there may be a significant lag between a change in ambient temperature and any significant amount of ammonia condensing or boiling..

I have very little working knowledge of the navigating the skies. In the ocean, I am familiar with thermoclines, if there are similar conditions in the sky where you intend to balloon, a lag in altitude control based on ambient temperature could have the balloon headed down rapidly. Perhaps you already have a system to deal with this...heat the ammonia or drop sand bags? I'd be interested to learn how you deal with unintended rapid descent.

You mentioned mixing hydrogen with the ammonia. Even if you start with pure ammonia, you will get nitrogen and hydrogen gas in your balloon. Exposed to moderate energy gammas (or fast neutrons, or other high energy particle) ammonia decomposes to hydrogen and nitrogen. So the longer you fly at high altitude, the more hydrogen should be wandering off from inside your balloon, leaving the sad nitrogen.

Another thought, Perhaps you could expose various materials to reflect or absorb light to control the temperature of the ammonia and altitude. ....

Some chemical heaters might help if all else fails.