Re: [Phys-L] simulation of "bonding"

["LaMontagne, Bob" <RLAMONT@providence.edu>]

I would expect that if the final state is not very temperature dependent. In water vapor condensation, it is. but if a molecule is formed, then I would expect the gross kinetic energy of the product to be temperature dependent but not the internal energy of the molecule.

When I was teaching, I used similar arguments to qualitatively explain heats of formation, but I could never give a convincing argument for a specific value of the heat of formation.

I would love to hear other thoughts on this.

Bob at PC
________________________________________
From: Phys-l <phys-l-bounces@www.phys-l.org> on behalf of Robert Cohen <Robert.Cohen@po-box.esu.edu>
Sent: Saturday, March 5, 2016 8:14 PM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] simulation of "bonding"

So if I give all of the particles some initial KE, you think that medium's gain in KE will depend on what initial KE I use?

Robert Cohen             Department of Physics                  East Stroudsburg University
570.422.3428             http://quantum.esu.edu/~bbq     East Stroudsburg, PA 18301


> -----Original Message-----
> From: Phys-l [mailto:phys-l-bounces@www.phys-l.org] On Behalf Of
> LaMontagne, Bob
> Sent: Friday, March 04, 2016 7:02 PM
> To: Phys-L@Phys-L.org
> Subject: Re: [Phys-L] simulation of "bonding"
>
> I was referring to particles that have the same average KE as the medium
> BEFORE the bonding. After the bonding the KE and PE is more or less fixed (not
> completely temperature dependent). The bonding energy is related to the KE
> before and after in these simulations. Therefore, the temperature is a factor.
>
> However, the model is good for qualitative predictions of heating and cooling
> when water condenses and evaporates.
>
> Bob at PC
> ________________________________________
> From: Phys-l <phys-l-bounces@www.phys-l.org> on behalf of Robert Cohen
> <Robert.Cohen@po-box.esu.edu>
> Sent: Friday, March 4, 2016 6:06 PM
> To: Phys-L@Phys-L.org
> Subject: Re: [Phys-L] simulation of "bonding"
>
> Interesting point, thanks.  I'm not sure I fully understand though.  Are you saying
> that the KE that the pair has after the bonding (compared to the potential
> energy that was lost) is not reflective of the real bonding process?  Or is it that
> the final KE of the pair in the simulation (on order of 1/50 of the initial potential
> energy) would be even smaller in a real bonding process because there would be
> more than just 100 particles making up the environment?
>
> Robert Cohen             Department of Physics                  East Stroudsburg
> University
> 570.422.3428             http://quantum.esu.edu/~bbq     East Stroudsburg, PA
> 18301
>
>
> > -----Original Message-----
> > From: Phys-l [mailto:phys-l-bounces@www.phys-l.org] On Behalf Of
> > LaMontagne, Bob
> > Sent: Thursday, March 03, 2016 4:15 PM
> > To: Phys-L@Phys-L.org
> > Subject: Re: [Phys-L] simulation of "bonding"
> >
> > Qualitatively, this simulation gives a mechanism for the medium to
> > gain kinetic energy when two particles bond. However, the bonding
> > energy is usually a fixed number. Assuming that the two particles have
> > the same average kinetic energy
> > (temperature) of the medium, then the implication is that the bonding
> > energy is temperature dependent.
> >
> > Bob at PC
> > ________________________________________
> > From: Phys-l <phys-l-bounces@www.phys-l.org> on behalf of Robert Cohen
> > <Robert.Cohen@po-box.esu.edu>
> > Sent: Thursday, March 3, 2016 3:27 PM
> > To: Phys-L@Phys-L.org
> > Subject: [Phys-L] simulation of "bonding"
> >
> > I wanted to show students how "bonding" releases energy but couldn't
> > find any simulations online so I wrote one based on Bruce Sherwood's
> > programs (which I have found to be a great resource, by the way).  Not
> > sure if this is useful to anyone else but my students found it very
> > useful and I figured I'd pass it on in case (a) anyone else wants to
> > use them or (b) it doesn't really show what I want it to show and someone (in
> which case I am sure someone will correct me).
> > One simulation shows two particles under an attractive force, allowing
> > for elastic collisions.  They just continue to bounce off each other.
> >
> > <
> > http://www.glowscript.org/#/user/rcohenpa/folder/Public/program/charge
> > pair
> > interaction>
> >
> > The other simulation shows the same two particles but in a field of
> > neutral particles.  The two particles eventually "stick together"
> > after transferring their energy to the surrounding particles.
> >
> > <
> > http://www.glowscript.org/#/user/rcohenpa/folder/Public/program/charge
> > inte
> > ractions>
> >
> >
> > Robert Cohen             Department of Physics                  East Stroudsburg
> > University
> > 570.422.3428             http://quantum.esu.edu/~bbq     East Stroudsburg, PA
> > 18301
> >
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