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Author Topic:   Entropy and the immutable law of death
Rrhain
Member
Posts: 6351
From: San Diego, CA, USA
Joined: 05-03-2003


Message 76 of 83 (434001)
11-13-2007 11:10 PM
Reply to: Message 67 by ChemEbeaver
11-13-2007 2:41 PM


ChemEbeaver responds to me:
quote:
but from a chemistry point of view "disorder" is very important to entropy.
Not at all. "Disorder" is merely a metaphor to describe a physical state. As the statistical definition of entropy tells us (and I can go into that one, too, if you wish...but you really ought to know it), entropy has to do with the number of available quantum states. To call this "order" is to impose a consciousness upon the system which does not exist. "Order" is a subjective term and science doesn't deal with subjectives.
quote:
Entropy also depends on the state of matter
Um, you do realize that the state of matter indicates the amount of energy available, yes? I went through that entire section about change of phase for a reason. When you add or remove heat to a substance at its phase point, you don't change the temperature. You merely change the phase.
The state of the matter is a function of how much energy is available.
quote:
Contrary to its name, thermodynamics is more than about "heat" as heat is only one aspect of it. Thermodynamics is about energy.
Indeed.
And what is heat if not energy? I went through the entire concept about the Zeroth Law for a reason. We use the kinetic definition of temperature for a reason. It is because the molecules are physically moving around. By adding heat (i.e., energy) to the system, we cause an increase in temperature because that energy is being used to make the molecules move faster.
quote:
Molecules seek the most stable configuration at the lowest energy states which is why they favor disorder over order.
But "disorder" and "order" are merely metaphors for the quantum states we are trying to describe. "Order" is a subjective term and science doesn't deal with subjectives.
For certain substances, the solid state has multiple variations. Carbon, for example, has three stable solid states: Graphite, fullerenes, and diamond. Each has a specific absolute entropy that has to do with the quantum states available, not the "order" of the crystalline structure.
Ice has a dozen different crystalline structures, again with specific absolute entropies, but they are tied to quantum states, not the "order" of the crystal.

Rrhain

Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.

This message is a reply to:
 Message 67 by ChemEbeaver, posted 11-13-2007 2:41 PM ChemEbeaver has not replied

  
ChemEbeaver
Junior Member (Idle past 5974 days)
Posts: 18
From: Aloha, OR, USA
Joined: 11-09-2007


Message 77 of 83 (434022)
11-14-2007 1:16 AM
Reply to: Message 74 by ringo
11-13-2007 4:31 PM


Yea I wrote it wrong. I think the correct reaction is:
H2O + H+ -> H3O+
H2O -> OH- + H+
= 2 H2O -> H3O+ + OH-

This message is a reply to:
 Message 74 by ringo, posted 11-13-2007 4:31 PM ringo has replied

Replies to this message:
 Message 79 by ringo, posted 11-14-2007 10:11 AM ChemEbeaver has replied

  
ChemEbeaver
Junior Member (Idle past 5974 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
Beauty Blog - For girls who keep up with the times
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).
Chemist Salary | PayScale
Chemical Engineer Salary | PayScale
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

  
ringo
Member (Idle past 411 days)
Posts: 20940
From: frozen wasteland
Joined: 03-23-2005


Message 79 of 83 (434075)
11-14-2007 10:11 AM
Reply to: Message 77 by ChemEbeaver
11-14-2007 1:16 AM


ChemEbeaver writes:
I think the correct reaction is:
H2O + H+ -> H3O+
H2O -> OH- + H+
= 2 H2O -> H3O+ + OH-
I think you're looking at it backwards when you talk about "breaking" bonds. There's an equilibrium between neutral water molecules and ions. Bonds are constantly forming and breaking spontaneously.
There's no energy change in the population of molecules/ions - i.e. no heat flow in or out of the beaker of water. Therefore, thermodynamic calculations on whether or not a bond can "break" are irrelevant.

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This message is a reply to:
 Message 77 by ChemEbeaver, posted 11-14-2007 1:16 AM ChemEbeaver has replied

Replies to this message:
 Message 81 by ChemEbeaver, posted 11-19-2007 1:49 AM ringo has not replied

  
crashfrog
Member (Idle past 1466 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 80 of 83 (434184)
11-14-2007 8:05 PM
Reply to: Message 78 by ChemEbeaver
11-14-2007 2:04 AM


It's correct, there are more ions at higher temperature, but it doesn't prove me wrong.
It does, because it's exactly what you said doesn't happen.
But it does happen.
Hydrogen bonds are broken by electric field:
What electric field? We're talking about pure water.
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).
That's fascinating, I guess, but I don't see the relevance.

This message is a reply to:
 Message 78 by ChemEbeaver, posted 11-14-2007 2:04 AM ChemEbeaver has replied

Replies to this message:
 Message 82 by ChemEbeaver, posted 11-19-2007 1:53 AM crashfrog has replied

  
ChemEbeaver
Junior Member (Idle past 5974 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 5974 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

  
crashfrog
Member (Idle past 1466 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 83 of 83 (435194)
11-19-2007 6:17 PM
Reply to: Message 82 by ChemEbeaver
11-19-2007 1:53 AM


Even pure water has an electric field since it is still bipolar.
Oh, you're talking about dipole moment.
But that just proves what I'm saying. Water's dipole moment only causes an interaction when the molecules are in proximity; ultimately, it's the kinetic action of heat that gets them into that proximity, which is why the concentrations of hydroxide and hydronium both increase when you heat pure water.
Which is precisely what you said would not occur. How do you explain this discrepancy?

This message is a reply to:
 Message 82 by ChemEbeaver, posted 11-19-2007 1:53 AM ChemEbeaver has not replied

  
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