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Author Topic:   Entropy and the immutable law of death
ChemEbeaver
Junior Member (Idle past 6004 days)
Posts: 18
From: Aloha, OR, USA
Joined: 11-09-2007


Message 78 of 83 (434033)
11-14-2007 2:04 AM
Reply to: Message 75 by crashfrog
11-13-2007 4:45 PM


quote from crashfrog:
At higher room temperatures than 25 deg. C, there are greater concentrations of both ions, which proves you wrong
It's correct, there are more ions at higher temperature, but it doesn't prove me wrong.
Hydrogen bonds are broken by electric field:
Geissler et al. have determined that electric field fluctuations in liquid water cause molecular dissociation (2). They propose the following sequence of events that takes place in about 150 fs: the system begins in a neutral state; the solvent's electric field breaks a hydrogen bond between two water molecules, creating a hydroxide and hydronium ion
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quote from crashfrog:
Temperature is a statistical property, which means that, in any substance at a certain temperature, some molecules of it have greater kinetic energy than average, and some have less than average. Arrhenius proved this, and it's why most chemical reactions display a continuous relationship between temperature and rate, rather than the discontinuous relationship one would expect from the examination of activation energies alone.
Hell, I have the lab notes to prove it.
Yes that's correct temperature is the average of kinectic energy. But that doesn't mean the upper end of the kinetic energy of room temperature is enough to break the strong hydrogen bonds. I don't doubt you have the notes, I only doubt your understanding of the notes.
quote from crashfrog:
Don't they teach chem engineers any chemistry at all?
We take the same chemistry class as chemists: gen-chem, o-chem, p-chem, inorg-chem, surface chem, etc. I am not sure about other university, but at mine chemEs are always at the top of the chemistry classes.
As for thermodynamics, we learn it from three perspectives: one term in P-chem, two terms in engineering (heat transfer) and three terms in CHE thermo.
This is probably why chemical engineers can come out after four years and is able to do real work earning an industry's average of $56,850 a year. Whereas chemist requires a master to do any real work and still gets paid less ($53,879).
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Edited by ChemEbeaver, : changing a word

This message is a reply to:
 Message 75 by crashfrog, posted 11-13-2007 4:45 PM crashfrog has replied

Replies to this message:
 Message 80 by crashfrog, posted 11-14-2007 8:05 PM ChemEbeaver has replied

  
ChemEbeaver
Junior Member (Idle past 6004 days)
Posts: 18
From: Aloha, OR, USA
Joined: 11-09-2007


Message 81 of 83 (435105)
11-19-2007 1:49 AM
Reply to: Message 79 by ringo
11-14-2007 10:11 AM


I'm pretty sure you can do calculations based on the energy states of the enthalpy and entropy of the initial and final to find if the reaction (of breaking the bonds and forming new ones) is spontaneous at temperature T, pressure P, concentration X...etc.
Although there isn’t any net change in energy of a "population" since, as you said, it happens in equilibrium, the calculation is useful for finding the theoretical values (spontaneous or not) of a molecule or mole (or in this case 2 water) not in equilibrium.
But I realized, just as you said also
calculations on whether or not a bond can "break" are irrelevant
since there is no amount of heat that can break chemical bonds, if I recall correctly from electrolysis.
(I was trying to point out to crashfrog that heat wasnt the reason water self ionizes).

This message is a reply to:
 Message 79 by ringo, posted 11-14-2007 10:11 AM ringo has not replied

  
ChemEbeaver
Junior Member (Idle past 6004 days)
Posts: 18
From: Aloha, OR, USA
Joined: 11-09-2007


Message 82 of 83 (435106)
11-19-2007 1:53 AM
Reply to: Message 80 by crashfrog
11-14-2007 8:05 PM


What electric field? We're talking about pure water
Even pure water has an electric field since it is still bipolar.
I remember now from electrolysis that heat cannot break chemical bonds; heat can only increases the breaking of the bonds.

This message is a reply to:
 Message 80 by crashfrog, posted 11-14-2007 8:05 PM crashfrog has replied

Replies to this message:
 Message 83 by crashfrog, posted 11-19-2007 6:17 PM ChemEbeaver has not replied

  
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