Has there been an improved understanding of water ?

Discussion in 'Chemistry' started by river, Aug 16, 2013.

  1. Trippy ALEA IACTA EST Staff Member

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    The bonding in liquids is generally the same as the bonding in solids, the difference between them is the energy of the particles.
     
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  3. arauca Banned Banned

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    Are you saying material in solid and in liquid , what about the step , latent solidification does not exist ?
     
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  5. Trippy ALEA IACTA EST Staff Member

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    This doesn't quite make sense. Care to rephrase? Are you asking me about latent heat? If so, take a moment to think about what I said and what latent heat is...
     
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  7. arauca Banned Banned

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    you take the time , again explain " bonding in liquids is generally the same as bonding in solids " Ij many solids there is an amorphous phase ( referred as solid solution and there is a crystalline phase which is an ordered bonding in a variety of geometric orders.
     
  8. kurros Registered Senior Member

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  9. wellwisher Banned Banned

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    In liquid water, hydrogen bonding forms clusters of water molecules. In ice these clusters have to expand to form hexagonal arrangements within itself and with other clusters. Again, it is all hydrogen bonding but different arrangements. Liquids have more entropy than do solids. The disorder results in hydrogen bonding that reflects the higher levels of entropy.

    My favorite property of water, which is important to life, is the entropic force. This is the fifth force of nature and is based exclusively on an increase in entropy, generating a force. This is commonly seen in osmosis, with the force connected to osmotic pressure P=F/A. The scenario is created by a semi-permeable membrane that allows water diffusion but restricts other solutes from moving. The water will diffuse in the direction of higher solute concentration to increase entropy.

    Osmosis is a colligative property of water, which means it occurs independently of the character of the solute. It is only dependent on the concentration or atom/ion count. This is why electromagnetic force is factored out. We can use single or double ions or polar molecules, and only the number matters not which we use. It is pure entropy generating a force. In cell cycles, the cell uses the entropic force to expand the mother cell before division into daughter cells; osmosis.

    On the diagram below, on the right, the pressure head is connected to the entropic force. Like I mentioned before, liquids can have two force vectors at steady state. On the right diagram at steady state, the left side is under a given pressure head, while the right side has less pressure head, yet water is freely diffusing in both directions at the membrane like there is no net force. Before steady state as the pressure head is building water is flowing in the direction of higher pressure due to the entropic force.

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  10. origin Trump is the best argument against a democracy. Valued Senior Member

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    Wellwisher, this is the science section of the forum - in science we are not allowed to just make up stuff and pass it off as science. Do you understand what I mean? I mean saying junk like "entropy is the fifth force". It is not good form in science to replace research with ignorance and guesses.
     
  11. Trippy ALEA IACTA EST Staff Member

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    Here you're confusing the solid phase with what I mean.

    Look, if hydrogen bonding keeps the liquid together, then it's hydrogen bonding that keeps the solid together. The difference between the liquid and the solid is that the particles in the liquid have sufficient energy to partially overcome the intermolecular forces where those in the solid do not.

    It's really not that hard.
     
  12. wellwisher Banned Banned

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    Glass that you use for windows appears to be a solid, but will flow over long periods of time like it is a liquid. If you look at old glass manufactured hundreds of years ago, the bottom is thicker than the top due to flow. It is liquid over longer periods of time, but solid in the short term. I suppose the definition is again based on time scale.

    In the chemistry glossary;

    Water is an exception in that ice expands upon freezing causing the particles to separate. But once solid it tends to be stable in shape and volume. In case of the glass, it decreases volume upon solidification, but the shape stability is a function of time. This is why I am hesitant to over simply the definition, although that would make it easier for you.
     
  13. wellwisher Banned Banned

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    Pressure is force/area, correct? The pressure above is called osmotic pressure, correct? Osmosis is a colligative property, which means it is based only on entropy, correct? We have a force, based on entropy, where entropy is the second law of science and rates higher than force laws which are not in the top two. Entropy is only behind energy. I coined the phrase "entropic force". You must be a memorizer and were never taught how to reason and think without group floaties.
     
  14. origin Trump is the best argument against a democracy. Valued Senior Member

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    False. What a shock! Instead of making something up this time you have presented an urban ledgend as fact.
     
  15. origin Trump is the best argument against a democracy. Valued Senior Member

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    Incorrect. Please supply the equation (or source) that shows the entropy (S) is the driving force of osmotic pressure.

    I am coining the term "entropic confusion" to describe your misunderstanding and obsession with entropy.
     
  16. exchemist Valued Senior Member

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    Well……actually, isn't the phenomenon of osmosis due to entropy? The numbers of particles diffusing through the membrane in each direction only become equal once the concentrations on both sides of it are equal. That is a statistical, Maxwell's Demon type, effect, is it not?

    However osmotic pressure is not a pressure exerted by this process, it is the artificially applied pressure differential one needs to exert across the membrane, in order to STOP the osmosis. So it isn't a force driven by entropy.

    So the osmotic pressure example doesn't justify calling entropy the 5th "force". It is NOT a force, whereas gravitation, EM, Weak and Strong Forces are.

    Entropy represents a tendency in nature arising from the statistics of the kinetic theory of matter. But that does not make it a force.
     
  17. Trippy ALEA IACTA EST Staff Member

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    Glass panes that were made hundreds of years ago we made by taking a lump of molten glass, rolling it, expanding it, and flattening it. It was then spun into a disc and cut into panes. These panes were then installed heavy side down. Interestingly, there's been work done on this as recently as may 2013 which suggests that glasses do not actually behave as liquids: The ‘glass is a liquid’ myth has finally been destroyed

    Most solids are capable of viscous flow when subjected to appropriate stress-strain regimes - this is why unsupported solids sag over long time frames. Somewhere I have seen a photo of a marble bench that has sagged in the middle because of this. Much of the Earth's interior is a solid that is capable of plastic (or was it ductile?) viscous flow because of the combination of the temperature and pressure.

    It's a general statement someone says a group of things 'tend to do this' then it means the majority of things do it, but some don't. Water, incidentally, is not the only exception to the rule. Silicon, Gallium, Germanium, Antimony, Bismuth, and Acetic acid all expand on freezing. In fact silicon exapnds more when it freezes than water does.

    Actually, it's capable of undergoing viscous flow under appropriate stress-strain regimes, just like any other solid. Here's an example of it doing so:

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    No, it's a function of the stress strain regime it is subjected to. Just the same as liquid water or solid steel.
     
  18. origin Trump is the best argument against a democracy. Valued Senior Member

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    I agree with everything you have said here, thanks for clearing up my muddled response. Wellwisher incorrectly thinks osmotic pressure is an actual pressure and then extends this misunderstanding to state that it is actually an entropic force that leads to the pressure...
     
  19. origin Trump is the best argument against a democracy. Valued Senior Member

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    2 things.

    First, that is a great picture of a glacier.

    Second, my wife is a ceramic engineer/glass technologist (she uses her intelligence wellwisher, weird huh?) and the whole "glass is a super cooled liquid that flows over time" really grinds her gears.
     
  20. Trippy ALEA IACTA EST Staff Member

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    Thanks, although,. it's not actually mine. Having said that, I do have some pictures of Fox Glacier and Franz Josef Glacier floating around, somewhere.

    I'll bet it does.
     

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