If I have two substances...

[SaltyNuts]

and one boils at let's call it 175 degrees, one boils at 200 degrees. I assume those a both probably "evaporating" at room temperature up to their boiling temperatures? Maybe the higher the temp before their boiling point the faster their evaporation? I'm trying to figure out if I have those two combined in one solution, and I want to get them separated as much as possible, I would guess I would bring the temperature of the solution to 175 degrees exactly, and no more, and let all the 175 boiling point liquid boil out into something ready to catch the steam? I assume if I did that there would still be SOME of the 200 degree boiling point liquid that would have evaporated and caught with the steam of the 175 boiling degree liquid? If that is right, is there any way to eliminate that 100%?

Also, is there a name for a device where you can catch the steam that comes out and covert it to liquid? I would guess its like a glass hat over the beaker of boiling liquid that curves over into another beaker, and then that end of the glass hat tube that is above the new beaker is cooled. So the hot steam comes out of the boiling liquid, is caught in the glass hat, and then chills as it moves through the glass hat tube into the other beaker, falling as liquid into the other beaker. But that is just me making something up that I think would work LOL.

Thanks!!!

 

[rcpratt]

You're describing distillation and condensers. Boiling a liquid is called vaporization, not evaporation. What you're describing may be possible, but distillation is often not effective for separating liquids whose boiling points lie close to one another.

 

[herm0016]

and one boils at let's call it 175 degrees, one boils at 200 degrees. I assume those a both probably "evaporating" at room temperature up to their boiling temperatures? Maybe the higher the temp before their boiling point the faster their evaporation? I'm trying to figure out if I have those two combined in one solution, and I want to get them separated as much as possible, I would guess I would bring the temperature of the solution to 175 degrees exactly, and no more, and let all the 175 boiling point liquid boil out into something ready to catch the steam? I assume if I did that there would still be SOME of the 200 degree boiling point liquid that would have evaporated and caught with the steam of the 175 boiling degree liquid? If that is right, is there any way to eliminate that 100%?

Also, is there a name for a device where you can catch the steam that comes out and covert it to liquid? I would guess its like a glass hat over the beaker of boiling liquid that curves over into another beaker, and then that end of the glass hat tube that is above the new beaker is cooled. So the hot steam comes out of the boiling liquid, is caught in the glass hat, and then chills as it moves through the glass hat tube into the other beaker, falling as liquid into the other beaker. But that is just me making something up that I think would work LOL.

Thanks!!!

its called a condenser. https://www.fishersci.com/us/en/browse/90094019/Condensers?searchType=typeahead

those temps are not that far apart, you will have to do it many times and you will never get to 100%. its like stepping half way to the wall continuously, you never reach the wall, but you get close enough.

 

[SaltyNuts]

Thanks guys! And I'll never get there 100% because even if the second one boils at 200 degrees, and even if I keep the temperate right at 175 (the boiling point of the first one), some of the second one will still vaporize even though its boing point has not been reached?

I see that if you do it 2 or 3 times the amount of the one that boils at 200 degrees would probably indeed be very, very small.

Thanks!

 

[Stiff Clamp]

CPU getting hot?

 

[herm0016]

@nsa @FBI
I have no knowledge of the use of this information.


lol, both of those are real accounts that have never posted.

 

[pete6032]

Thanks guys! And I'll never get there 100% because even if the second one boils at 200 degrees, and even if I keep the temperate right at 175 (the boiling point of the first one), some of the second one will still vaporize even though its boing point has not been reached?

I see that if you do it 2 or 3 times the amount of the one that boils at 200 degrees would probably indeed be very, very small.

Thanks!

Seems to me like you could get the 200 degree one to 100% purity by raising the temperature to anything over 175 and holding it there until all of the 175 boils off.

 

[MrSquished]

What are the two substances, hookers and blow?

 

[SaltyNuts]

Seems to me like you could get the 200 degree one to 100% purity by raising the temperature to anything over 175 and holding it there until all of the 175 boils off.

That makes sense. But the 175 one will have some of the 200 degree on in there correct?

 

[uclaLabrat]

Seriously go study some ochem. Take some classes. You need to learn the theory but more importantly, the safety.

 

[compcons]

That makes sense. But the 175 one will have some of the 200 degree on in there correct?

No. It literally stays a liquid until 200 and WILL NOT turn into a gas. This is freshman Chem stuff. Now the problem is likely being able to heat the solution to 175 and have it stay within a degree or two. 25 degrees is actually a really big difference. It's hard when boiling points are within less than 5 degrees that things get tougher (but still doable).

You will likely have other contaminates that boil at less than 175 which means you don't want to collect that condensate. Basically from room Temp to 175 you will throw the condensate away and then once you get to 175, you will probably toss a little bit away. Once things stabilize, you can collect pure 175 substance. Your yield will not be 100%. Repeat for 200 degree substance.

If this is something you will do regularly, it is probably worth investing in the necessary equipment like a heating device that can hold its temp to +/- a degree or better. The condensers are less precise. Basically pump cooling water through it and drop the temp of the vapor by a couple of degrees and collect the condensate.

 

[uclaLabrat]

Vapor pressure of substances is temperature dependent but it's not zero below the boiling point, otherwise liquids wouldn't evaporate until they boiled, which everyone knows is not the case.

Depending on the distillation, simple distillation can generally be used to separate substances differing by about 20 deg, other than tjat you'd have to go to fractional distillation with a pretty efficient column. That can get you down to differences of 2 deg C depending on the efficiency. In practice I've struggled with good separation with differences smaller than 5 deg C.

Anything over 120-130 should be distilled under vacuum.

 

[brianmanahan]

CPU getting hot?

my potassium nitrate is hot with solution

 

[SaltyNuts]

Vapor pressure of substances is temperature dependent but it's not zero below the boiling point, otherwise liquids wouldn't evaporate until they boiled, which everyone knows is not the case.

Depending on the distillation, simple distillation can generally be used to separate substances differing by about 20 deg, other than tjat you'd have to go to fractional distillation with a pretty efficient column. That can get you down to differences of 2 deg C depending on the efficiency. In practice I've struggled with good separation with differences smaller than 5 deg C.

Anything over 120-130 should be distilled under vacuum.

Thank you Labrat! What you say always seems to make sense to me, so logical. When you say "Anything over 120-130 should be distilled under vacuum", you talking Celsius I assume? And what does "distilled under vacuum" mean? And why do it that way?

Thanks so much as always!!!!

 

[SaltyNuts]

No. It literally stays a liquid until 200 and WILL NOT turn into a gas. This is freshman Chem stuff. Now the problem is likely being able to heat the solution to 175 and have it stay within a degree or two. 25 degrees is actually a really big difference. It's hard when boiling points are within less than 5 degrees that things get tougher (but still doable).

You will likely have other contaminates that boil at less than 175 which means you don't want to collect that condensate. Basically from room Temp to 175 you will throw the condensate away and then once you get to 175, you will probably toss a little bit away. Once things stabilize, you can collect pure 175 substance. Your yield will not be 100%. Repeat for 200 degree substance.

If this is something you will do regularly, it is probably worth investing in the necessary equipment like a heating device that can hold its temp to +/- a degree or better. The condensers are less precise. Basically pump cooling water through it and drop the temp of the vapor by a couple of degrees and collect the condensate.

You second sentence - "It literally stays a liquid until 200 and WILL NOT turn into a gas. " I think this is 100% wrong, clearly 100% opposite of what I was taking about in my first post and what UCLALabRat posted, which I agree with UCLALabRat was basically common knowledge LOL....

 

[BoomerD]

Seems like the OP should take some chemistry classes.

 

[SaltyNuts]

Seems like the OP should take some chemistry classes.

You better take some self-defense classes after pissing me off with that post.... I will put you through a wall...

This is WAY over the line.

Perknose
Forum Director

 

[Paperdoc]

This is part of the whole field of Colligative Properties in Physical Chemistry. The actual Boiling Point of a Solution of two different liquids is almost always HIGHER than the Boiling Point of either pure component, and it depends on the composition of the particular mixture (that is, what percentage of the mixture is Component A). An example of this is used every day in automobile radiators. Most car owners in North America have their cooling system filled with antifreeze. Well, actually they have a mixture of Ethylene Glycol and Water with a few minor additives for corrosion inhibition.. We tend to concentrate on how this mixture will NOT freeze until it gets much colder than 0 C (32 F), so it prevents that liquid from freezing in cold weather. But that mixture ALSO has a Boiling Point HIGHER that 100 C (212 F), so it prevents having the mixture boil in hot weather under heavy engine workloads.

The graph of Boiling Point versus % Composition is called a Phase Diagram. It is VERY common that this graph is composed of two curves that meet at some point in the range where the maximum Boiling Point is reached. When you try to separate the components by distillation the composition of the liquid phase changes as one component (with the higher vapour pressure) is selectively removed from the liquid system, and the Boiling Point is shifted higher. But at some point you get to the max Boiling Point composition and then the vapours boiling off have exactly the same composition as the liquid phase, and you cannot force the system to any higher temperature, nor can you use distillation to separate any further. For example, a mixture of Ethyl Alcohol (the drinkable stuff) and water has this high-temp point about 95% alcohol and 5% water, so when you distill a fermented batch you can NOT get the alcohol content to any higher than about 95%.

What OP is talking about really is best viewed as a special version of distillation called Fractional Distillation used to separate fractions (components) of a mixture. This is done widely in chemical processing using various designs of Fractionating Columns - the common ones in petroleum refineries are known by the shorter "Fracking Columns". Small-scale systems of this type are used in labs all the time. I've even used a sophisticated version of this called a Spinning Band Fractionation Column.

Regarding the "distill under vacuum" above, that process uses a distillation apparatus that can be closed up and sealed from the air, then have air and vapour sucked out by a pump so the pressure inside the still is below atmosphere. In that system you can get the liquid phase to boil at a lower temperature because of the lower vapour pressure inside. Why do this? Some components of such a mixture may undergo chemical reactions at high temperatures creating undesirable side products. Reducing the pressure inside allows the distillation to be carried out at a lower temperature, avoiding this problem.

 

[sdifox]

 

[snoopy7548]

All I know is if you add salt to water, it raises the boiling point, and adding lemon juice when you've over-salted food counteracts the salt flavor.

So by that logic, if you want to lower the boiling point in order to do this more safely at home, just add some lemon juice.

 

[compcons]

You second sentence - "It literally stays a liquid until 200 and WILL NOT turn into a gas. " I think this is 100% wrong, clearly 100% opposite of what I was taking about in my first post and what UCLALabRat posted, which I agree with UCLALabRat was basically common knowledge LOL....

I probably wasn't clear in my respone. If the boiling point of a compound is 200, NONE of that compound will be present as a gas below 200. So if you want to separate them, you have 25 degrees to work with when isolating the compounds. If my explanation sucks, I aplogize.
I gave up my life as a chemist long ago but I did a lot of sample prep work with some pretty interesting materials including waxes and oils.

 

[Captante]

What are the two substances, hookers and blow?

We can hope!

 

[Paperdoc]

compcons, you were incorrect there; SaltyNuts is much closer.

At ANY temperature, there will be an equilibrium between the liquid and gaseous phases of that compound that boils at 200. That is, in the air space (or whatever gases occupy that space) above the liquid surface there WILL be some of the gaseous version of that compound present. One way to measure the quantity of that is called Partial Pressure. Now, the pressure of a "Standard Atmosphere" of air on our planet is sufficient to support a column of Mercury (the densest liquid we have) 760 mm high. So we use those units to measure air pressure: 760 mm Hg is one Standard Atmosphere. In the space above the surface of the liquid compound the amount of its gaseous phase can be quantified in mm of Hg. For example, a Partial Pressure of 63 mm Hg would say the gas mix above the liquid in less than 10% of that compound, and the rest is all other air components. This DOES happen at all temperatures under which the compound is a liquid, and even DOES happen when that compound is cold enough to become a solid, although the Partial Pressure at that temperature is quite low, but NOT zero. An example? Frost. Frost coats surfaces with the solid (ice) phase of water when the temperature of the surrounding air is below 0 C (32 F). Where does that water come from? It is water in gaseous phase dissolved in the air - the water has a non-zero concentration and Partial Pressure in the surrounding air, and some of that can be converted to solid ice crystals adhering to surfaces like windows.

The Partial Pressure of a liquid depends on the temperature it is at - higher temps = higher Partial Pressure. The DEFINITION of the Boiling Point of the liquid is the temperature at which its Partial Pressure equals the surrounding applied pressure. So what we normally call its Boiling Point is the temp at which the Partial Pressure equals normal atmospheric pressure, 760 mm Hg. But if you place that liquid compound in a closed system and change the pressure, the temperature at which it BOILS changes. Vacuum distillation (discussed above) is one technique that makes use of this - you can distill something at reduced temperature if you do it in a closed system at reduced pressure. Another example is a car radiator and cooling system. These days all rads are closed systems that have a pressure-release cap on them, usually set to 15 PSI (one atmosphere) above normal atmospheric pressure, so that the rad fluid will boil at a HIGHER temperature than "normal" 100 C (212 F).

When you boil a mixture of two compounds with different normal Boiling Points, the gaseous phase in the space above them contains gases of BOTH compounds, each with different Partial Pressures. The one with the lower Boiling Point produces a higher Partial Pressure in that mix and hence is the more concentrated component in that space. But the space contains gaseous phases of BOTH compounds. The process of Fractional Distillation depends on these differences in Partial Pressure and the impact that has on the condensation of those gasses back to a liquid phase to accomplish separation of the compounds.