Is "vaporizing" actually the act of vaporization?

[Nebulous]

Hey all, I've got a chemistry-based question about what our favorite activity should be called from a scientific standpoint.

In chemistry, when a substance changes from gas to liquid, liquid to solid, etc, the process is called a phase transition.

http://en.wikipedia.org/wiki/Phase_transition

Vaporization is defined in chemistry as the change from liquid to gas state. When you boil water, you are "vaporizing" the liquid water molecules into gaseous water molecules.

My question is if the psycho-active compounds in marijuana are vaporized from a liquid to gaseous state. As it appears the compounds in our weed are initially in a solid state (we dry the stuff after all), the act of chemical "vaporization" would subsequently require melting of the compounds from a solid to liquid state, and then boiling/vaporizing them into gaseous vapor state. I don't think this is the case. Instead, I believe our vaporizers achieve the act of sublimation, which is direct transition from solid to gas, bypassing the liquid state. A classic example of sublimation is dry ice - the solid ice cubes turn to gas without melting.

What a chemist would call our notion of vaporization may be largely irrelevant to the task at hand, but I find it interesting to think that I am actually subliming my herb instead of vaporizing. And of course, sublimation calls to mind sublime, which is a word we can all agree describes the vaporization experience quite well


This diagram is useful when trying to visualize the various phase transitions.

 

[mrfloopa]

As it appears the compounds in our weed are initially in a solid state (we dry the stuff after all), the act of chemical "vaporization" would subsequently require melting of the compounds from a solid to liquid state, and then boiling/vaporizing them into gaseous vapor state.

I'm no chemist, but just because something is in a solid doesn't necessarily mean it is a solid..? It may have been because of the use of the word vaporization, but I always imagined the chemicals in a plant are more gel-like than solid. In that case, the chemicals would vaporize.

 

[Stu]

I read somewhere that the process is called volatisation.

Or I am totally mistaken. Take your pick.

 

[Hippie Dickie]

the guy who invented the Eterra (log type vape) got the idea from the pyrolysis plant he was working at.

The "Processes for biomass pyrolysis" section seems somewhat on point.

i am very definitely seeing a "heat of vaporization" cooling effect in my vape -- i.e. there is a liquid going to gas (i think) ... well, maybe the same thing happens in sublimation??? idk

 

[OhTheAgony]

I think I'll just stick to vapin', stop mezzing with my head plz

 

[Hippie Dickie]

i love these discussions ... spending 30 minutes in Wikipedia is always rewarding. i see several new vape ideas in that section i mentioned above.

 

[dcorp]

Cannabinoids, including THC are oils and they have their specific boiling temperatures. So i think technically it is still vaporization - when the vaporizer reaches the required temperature the oil in your plant starts to boil and evaporates.

 

[vap999]

The desired herbal components are not in a solid state. Rather, they are notoriously sticky/gunky essential oils (liquids) that strongly adhere to most any surface, cellulose fibers (the structural component of plants) in this case.

"Vaporization," as the term is used, really involves two different physical processes. The basic process involved may be termed "thermal desorption," involving desorption, unbinding or dissociation of essential oil molecules adsorbed onto (sticking to) plant cellulose fibers using heat, followed by by vaporization (the phase shift from liquid to gas). Each process requires its own thermal energy.

 

[nicelytoasted]

I too, prefer to think of what we do to our beloved herb as thermal desorption, which is fundamentally a thermally induced physical separation process defined by thermodynamics as conversion of a substance from a liquid or solid state to a gaseous or vapour state by the application of heat (or reducing pressure), or by a combination of these processes.

This process does actually volatilize the trichomes, containing the cannabinoids and terpenes, into the stream of heated air, the result being a mix of vapour, aerosols and particulates of varying sizes.

These terms are mostly interchangeable, so I can see using either or all to describe what we refer to as vapourizing, imo.

 

[weedemon]

but they melt don't they? i see what you are saying about them being a solid to begin with, but look at good hash you apply heat and it melts into a liquid then bubbles away right?

maybe it melts then vaporizes?

interesting theory though man.

 

[Nycdeisel]

good question weedemon,

all good food for thought

I would like to agree with what dcorp said but I ahve not read those articles linked(yet.... ) but I sure am interested int this.

 

[djonkoman]

from my experience I would think it's just vaporisaton
you can crumble hash by shortly heating it with a flame to make it softer

and if I put a piece of hash in my VG and look after a few hits, the hash is solid but with bubbles, wich to me seems to indicate it gets soft first, more aproaching liquid(but since it's a mixture also some solids), wich then boils and vaporizes, leaving behind the solds that after it doesn't produce any hits anymore is dry and crumbly

but that's in no way scientific ofcourse

 

[High Sigh]

Since when is vaporizing the change from a liquid to a gas?

Definition: Vaporization is the transition of matter from a solid or liquid phase into a gaseous (or vapor) phase. Water boiling into steam is an example of vaporization.

Go vape another one

 

[djonkoman]

since my highschool chemistryclasses?
I've learned that sema schematic posted above(albeit in dutch instead of english, and without plasma altough I learned about that myself from the internet)

 

[Nebulous]

Very interesting ideas being presented here. I certainly have a lot of wikipedia reading to do now

The wikipedia page for THC states the boiling point is 157 C, right around the vapor zone. So yeah, the molecules definitely are boiling. If I had ever used hash before I likely would have realized this also.

http://en.wikipedia.org/wiki/Tetrahydrocannabinol

Thanks for the help everyone!

 

[Qbit]

It's hash oil that demonstrates the liquid properties of cannabinoid oils. Heat a dab of hash oil up and it melts into a little puddle before it goes up in a puff.

 

[onox]

The desired herbal components are not in a solid state. Rather, they are notoriously sticky/gunky essential oils (liquids) that strongly adhere to most any surface, cellulose fibers (the structural component of plants) in this case.

"Vaporization," as the term is used, really involves two different physical processes. The basic process involved may be termed "thermal desorption," involving desorption, unbinding or dissociation of essential oil molecules adsorbed onto (sticking to) plant cellulose fibers using heat, followed by by vaporization (the phase shift from liquid to gas). Each process requires its own thermal energy.

I agree with this guy. Remember that sublimation at atmospheric pressure can only happen for certain compounds (like dry ice subliming into gaseous CO2). If you look at the phase diagram of any compound, there's a triple point. At temps/pressures below the triple point, sublimation can occur. At temps/pressures above the triple point, a solid compound will melt into a liquid before turning gaseous. I couldn't find a phase diagram for THC (can't really think of a good reason a researcher would make one, really), but I was unable to find a melting point. So I assume that vap999 is right when he says that the cannabinoid molecules are adsorbed onto plant fibers, and the high heat causes them to desorb, forming a liquid, which then boils and turns gaseous.

 

[biojuggernaut]

@qbit holy shit just like BHO on a hot skillet solid>liquid>gas! SO crazy and interesting

 

[Heos]

I thought it was the change from a liquid to gas, when we vaporize aren't we vaporizing the essential oils? Liquid.

 

[SD_haze]

I thought it was the change from a liquid to gas, when we vaporize aren't we vaporizing the essential oils? Liquid.

Essential oils aren't liquid though. Stu was correct when he mentioned volatilization.

Here's an explanation on why you dont vaporize THC, but instead volatilize it.

Recently, this process that has conventionally been termed vaporization has been re-named volatilization for scientific purposes to be more technically correct in some applications due to the fact that it is the volatile plant oils that are being released in a vapor like form in extractions from volatile oil containing plants. The term volatilization is more scientifically correct in that it refers to the process of converting a volatile oil into a gaseous state while vaporization technically refers to the conversion of something that is normally solid or liquid into a gaseous state (volatile oils having different properties than either solids or liquids).

[pulled from the VripTech website]

 

[Vapemania]

Very interesting ideas being presented here. I certainly have a lot of wikipedia reading to do now

The wikipedia page for THC states the boiling point is 157 C, right around the vapor zone. So yeah, the molecules definitely are boiling. If I had ever used hash before I likely would have realized this also.

http://en.wikipedia.org/wiki/Tetrahydrocannabinol

Thanks for the help everyone!

Well, I've been looking on Wiki also.

Thermal desorption seems to be a process where contaminants are vaporised off stuff.
So essentially, it's like burning off chemicals from soil by heating up the soil.
But does this answer whether THC is vaporised or sublimated?

Wiki says vaporisation is where the 'active compounds boil off into a vapor'.
So if boiling is occurring, then the THC is liquid.

But Wiki also defines THC as: 'in its pure form, it is a glassy solid when cold, and becomes viscous and sticky if warmed'.

So THC is solid.
The heating of the herb then changes the state of the THC from solid to liquid form.
It then 'boils off' into a gas.
So all three stages are occurring in the vaporisation process.
There is no sublimation.

However, the cold state of THC is solid.
IMO.

Essential oils aren't liquid though. Stu was correct when he mentioned volatilization.

Here's an explanation on why you dont vaporize THC, but instead volatilize it.

Recently, this process that has conventionally been termed vaporization has been re-named volatilization for scientific purposes to be more technically correct in some applications due to the fact that it is the volatile plant oils that are being released in a vapor like form in extractions from volatile oil containing plants. The term volatilization is more scientifically correct in that it refers to the process of converting a volatile oil into a gaseous state while vaporization technically refers to the conversion of something that is normally solid or liquid into a gaseous state (volatile oils having different properties than either solids or liquids).

[pulled from the VripTech website]

Ah, I think your post answers it.

So the THC is not actually solid or liquid.
It's a volatile oil.
Which has different properties to either a liquid or solid.

So vaporisation doesn't actually occur.
Instead, volatilization happens.

Wow. That was a trip!

mod note: use the edit button to avoid back to back posts. Merged.

 

[TriiKLe]

sublimination?

 

[vap999]

The active agents of interest are definitely liquids at room temperature, particularly when in a purified state. Viscous liquids, even referred to as oils, but definitely liquids, which can be poured and vaporized [or synonym - thermally desorbed, volatilized, etc.] into a gaseous state (which instantly becomes an aerosol) But in reality, everything is more complex and nothing is pure -- we are dealing with biological molecules, cells and tissues.

For those who perceive vaporization as involving a solid becoming a gas, I would ask them whether the plant material itself is solid? Yes, when you look at it or pick it up. But not when you look at the cellular or molecular levels.

We are dealing with dead plant cells, with fairly strong inert cellulose cell walls and their contents. See the plant cell graphic at http://micro.magnet.fsu.edu/cells/plantcell.html. Dead cells will, presumably, contain lots of air/space (after the materials have been cured and dried). What's left within the cell walls would be residual plant gunk containing essential oils, cellular debris/organelles, proteins, DNA, degraded chlorophyll, water, etc. with this sticking to the cells walls. For "vaporization," heat is applied to the plant material, the gunk heats up and likely at some point becomes much less viscous and spreads over the cell walls/cellulose fibrils. As heated, the various "liquid" components each has its own broad vaporization profile/range/spectrum, with there being no distinct boiling points with such complex mixtures adsorbed to plant material.

This is just a longer explanation of "vaporization" viewed as "thermal desorption." Obviously, with purified oils (no plant material), the process would be just vaporization/volatilization.

 

[Stu]

Interesting. Thanks for the insight, vap999.

 

[quantumjump]

My question is if the psycho-active compounds in marijuana are vaporized from a liquid to gaseous state. As it appears the compounds in our weed are initially in a solid state (we dry the stuff after all), the act of chemical "vaporization" would subsequently require melting of the compounds from a solid to liquid state, and then boiling/vaporizing them into gaseous vapor state. I don't think this is the case. Instead, I believe our vaporizers achieve the act of sublimation, which is direct transition from solid to gas, bypassing the liquid state. A classic example of sublimation is dry ice - the solid ice cubes turn to gas without melting.

For sublimation to occur (in the above example), the boiling point must be reduced to below the melting point of the substance, so the substance vaporizes before its melting point (as in a vacuum). While the transition from solid to liquid to vapor happens "instantaneously", the liquid state exists, and no sublimation is occurring.