alcohol evaporation

[RichD]

Why does alcohol evaporate so fast? I'm looking
for an explanation at the level of molecular dynamics.

--
Rich

[Mark Thorson]

RichD wrote:
>
> Why does alcohol evaporate so fast? I'm looking
> for an explanation at the level of molecular dynamics.

I presume you're comparing it to water.
The real question is why does water evaporate
so slowly. Based on molecular size and weight,
it should evaporate faster than propane.
The answer is hydrogen bonding. Hydrogen bonds
between oxygen on one molecule and hydrogen
on another molecule keep the water molecules
tied into a network. Alcohol has hydrogen bonds
too, but many fewer per unit of volume or weight,
so it evaporates more quickly. Ethyl alcohol
is about the same size and weight as propane,
but it evaporates much more slowly than propane
because of the hydrogen bonding it does have.

[Chris Richardson]

On Tue, 02 Oct 2012 13:16:27 -0700, RichD wrote:

> Why does alcohol evaporate so fast? I'm looking
> for an explanation at the level of molecular dynamics.

Molecular dynamics? My, my. What an impressive-sounding mouthful.

But it's the wrong mouthful. The explanation lies with intermolecular
forces.

Alcohol is not so special in this regard. Any common organic
compound will exhibit a similar rate of evaporation. Acetone
or hexane won't be around for long if you spill a bit on the
table top, for example. At room temperature, the rate of reaction
for X-liquid --> X-vapor is comparatively high due to the weak
intermolecular forces which, for organic molecules are largely
dispersion forces (van der Waals) or perhaps small dipole interactions.

[tj Frazir]

its boil point is lower as its vapour presure is /2 of water.
air presure makes a beed out of water to an edge thats twice as high .

http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[tj Frazir]

Its not hydrogen.
h2o is pushed together by 7 to 15 psi.
Its the easyest to push together.

alcohol is harder to push together and will boil sooner when a vaccume
is aplied .
at 10 psi the achohol is a gas and you can still make water.

at 6 psi you cant make water.

A compresor liquifies water the slowest.
it liquifies lp gasses quick at 300 psi and freeze pipes.

Compress air quick it gets hot as quick.
Liquifie gas can get hot real quick and expload.
pumping gas slow gets cold .



http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[Poutnik]

tj Frazir from Gravity...@webtv.net
posted Tue, 2 Oct 2012 21:15:37 -0400

>
> its boil point is lower as its vapour presure is /2 of water.

If this was true, the bp. would be higher.

> air presure makes a beed out of water to an edge thats twice as high .

Air pressure does not affect vapour tensions
( or just little for real gases ),

it affects only boiling point.



--
Poutnik

Current way of spaced quoting by GoogleGroups is disaster,
if combined with no quoting by some GG users.

[Chris Richardson]

On Tue, 02 Oct 2012 21:15:37 -0400, tj Frazir wrote:

> its boil point is lower as its vapour presure is /2 of water.
> air presure makes a beed out of water to an edge thats twice as high .
>

What a idiot!

The boiling point and vapor pressure are thermodynamic quantities
but we are concerned here with a rate, or kinetic, phenomenon.

Also, the "bead" form of water is caused by surface tension and
has nothing to do air pressure.

[G=EMC^2]

Same way oil evapoates slow. Read up on molecules TeBet

[Poutnik]

Chris Richardson from ro...@localhost.localdomain
posted 3 Oct 2012 07:03:08 GMT

>
> On Tue, 02 Oct 2012 21:15:37 -0400, tj Frazir wrote:
>
> > its boil point is lower as its vapour presure is /2 of water.
> > air presure makes a beed out of water to an edge thats twice as high .
> >
>
> What a idiot!
>
> The boiling point and vapor pressure are thermodynamic quantities
> but we are concerned here with a rate, or kinetic, phenomenon.

.. that is directly related to difference
between saturated and actual vapour pressure.

>
> Also, the "bead" form of water is caused by surface tension and
> has nothing to do air pressure.

[tj Frazir]

Boil poit of alc is 170 and BP of water is 220.
It will take less vaccum to boil the alc then the water.
a distalation only neads to boil the alc at 180 deg and not boil the
water its in to get the alc out of the water.

At room temp a vaccum can remove the alcohol from the water better then
disolation via steam alc condencing in a coil.

vapour presure will do the job.
a vaccume removes it from the water and air presure will re-condence the
alc in the next tank as its chilled and compresed.
No water will get to the other side.



http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[tj Frazir]

air presure is surface tensin dumbass.
Air presure is pushing water together .
its allso pushing alcohol together.

Remove the air presure with a vacuum pump.

NO ai presure no water and as the psi gets low the water boils at room
temp untill its ice or its a gas of h20.
air presure can make it water again as i remove the heat from
compressing it.

vapour presure just pushes liquids together.

Its thermal conductivity changes with vapour presure . You may not
compress a liquid but presure changes its feeze point. and its boil
point.








http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[tj Frazir]

Its boil poit is 170 deg when water is 220 deg so alcohol evapourtes
faster then water 1.2 times faster.
Im using vapour presure . to look at its evapouration rate.

I can change the vapour tension by adding or lowering air presure.
at room temp ...a vaccum on water freezes befor there water is gone BUT
its 1.2 times less vacccum to boil the alcohal.
Water room temp boils 70 deg F at air presure is 6 psi. yet at 15 psi
its room temp water ..lower the pai to 6 and 1/2 the water is vapour the
other half is ice ..at 20 deg F.

same for alc but it dont freeze and only neaded a vacuum to 10 psi to
be gas state.




http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[tj Frazir]

vacuum is the only way to get the alcohol out of a pile of grass treaded
with one cake in a gallon of water and left to rot.

at 15 psi you make less.. wine alc.
at 10 psi its 5 times faster but cant drop below 80 deg F or it kills
the yeast..

a slow vacuum in the sun tank o grass with it damp from the water and
yeast .. to 11 psi
then pumped down to 6 psi to get the alcohol out of the damp grass.
as the gras breaks down .


http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[tj Frazir]

remove the air presure and show me that beed .
NOW your saying psi only afects boil point.

water Lower te psi untill the boil point is less then freeze point
IDIOT.
Its that psi surface tension that pushes water together untill its a
liquid.

Te less psi air presure the lower the boil point.
The same force that resisted boiling at 400 deg F at 500 psi but at the
other end of the scale.

Your dumbshit thinks more psi higher boil point is a one way scale.

http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[tj Frazir]

is that a resonal prediction ! ¿

what do you mean boil point is higher when we add psi and not lower
when we lower psi ?

alc and water dont have the same vp.
the beed is 1.2 times higher in water .

alc has less beed at 15 psi.

http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[Poutnik]

tj Frazir from Gravity...@webtv.net
posted Thu, 4 Oct 2012 22:42:14 -0400

>
> Boil poit of alc is 170 and BP of water is 220.
> It will take less vaccum to boil the alc then the water.
> a distalation only neads to boil the alc at 180 deg and not boil the
> water its in to get the alc out of the water.
>
> At room temp a vaccum can remove the alcohol from the water better then
> disolation via steam alc condencing in a coil.
>
> vapour presure will do the job.
> a vaccume removes it from the water and air presure will re-condence the
> alc in the next tank as its chilled and compresed.

> No water will get to the other side.
>

You have forgotten about azetropic mixture alcohol water
with 95.63%w of alcohol.

[Poutnik]

tj Frazir from Gravity...@webtv.net
posted Thu, 4 Oct 2012 22:50:45 -0400

>
> vapour presure just pushes liquids together.
>

No, vapour pressure allows liquid evaporation.

[Bill Snyder]

On Thu, 4 Oct 2012 22:42:14 -0400, Gravity...@webtv.net (tj
Frazir) wrote:

>[the usual drived]

FOAD, moron. You aren't fooling anybody. And shove your
imaginary engine up your spamming, psychotic ass.

Everybody knows you have no engine, you have no yacht, you have no
money. Every post you make shows us all that you're a dumb,
illiterate bullshit artist.

And you can't even fool the Relfdroid any more. That must suck,
to be a crap-slinger who can't even fool the world's biggest born
sucker. Or maybe you get some kind of kick out of having everyone
laughing at you.

I wonder just how big a loser you are. Do you manage to hold some
kind of ultra-low-end job, of the WalMart greeter or "fries with
that" variety, or are you too crazy to be employable at all?

Interesting that the globe-trotting gazillionare with the huge
yacht and the mansion and all, posts from an ancient webtv
account. You'd think he could afford something a tiny bit
classier. I wonder if he lugs the TV around with him, or just the
set-top box? (Actually, I wonder if he's dialing in from his
trailer, or from his mommy's basement.)

You were mildly amusing when you first showed up, an illiterate
boob trying to pose as a zillionaire inventor, but that was years
ago. And there's nothing more boring than yesterday's stale joke.

--
Bill Snyder [This space unintentionally left blank]

[G=EMC^2]

On Oct 2, 4:16 pm, RichD <r_delaney2...@yahoo.com> wrote:

Fast moving molecles (cohesive force) TeBet

[tj Frazir]

I proved it.
170/220 1.2 times faster.

You said high VP raised the boil point.
And you failed to run that scale to the other end and lower psi till the
point the water dont boil is under its freeze point.

Now your just playing stupid

http://community.webtv.net/GravityPhysics/WhaleSteamEngineA

[Poutnik]

G=EMC^2 from herbert...@gmail.com
posted Fri, 5 Oct 2012 05:59:21 -0700 (PDT)

In fact ALCOHOL evaporates quite slow
because of strong hydrogen bonding of hydroxyl groups.
( Even if much weaker than in case of water ).

n-propane with comparable molecule mas and structure
( oxygen atom replaced by methylen group CH2 )
has boiling poing near -30 deg C,

more than 100 deg C below BP of alcohol.

Farther more, as there is higher molar enthalpy
of primary alcohol evaporation, comparing to n-alkanes,
vapor tension decreases faster for alcohols
with decreasing temperature.

Concerning molecular dynamics,
speed of evaporation of alcohol is usually driven by thermodynamics
and vapour difusion dynamics in the air.