Wednesday, March 24, 2010

Notes from Wednesday, March 24, 2010

So, we started the day off with some demonstrations that taught us a few things. For instance, the volume of a mixture of two liquids is not necessarily the sum of the volume of its components, supersaturated solutions form crystals when disturbed by the addition of more solute, and water and methanol can be made immiscible by adding a salt (in our case, KCO3). Why? Comment with your theories.

Here's the other things from today.
  • Pressure increases the solubility of gas in liquid. Increased pressure causes more gas particles to dissolve in the liquid, and decreased pressure allows more dissolved gas to escape from the liquid.
  • Henry's law: The solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid.
  • The rapid escape of gas from a liquid in which it is dissolved is known as effervesence.
  • Unlike a solid, increasing the temperature usually decreases gas solubility.
Since we have a short blog today, I leave you with another video, about the awesomeness of effervesence. Have a good night!
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15 comments:

  1. Will LongMarch 24, 2010 at 3:04 PM

    This comment has been removed by the author.

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  2. AnonymousMarch 24, 2010 at 4:52 PM

    I think the salt molecules' polarity gave it a stronger attraction to the water than the methanol, so because all the salt was taking up space near the water, the methanol was forced away

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  3. Patrick SweeneyMarch 24, 2010 at 5:59 PM

    I think that the two most poler molecules, salt and water, came together while the less polar molecule of methanol went off away from the other two. Great video Jim.

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  4. Jacob PoseyMarch 24, 2010 at 6:42 PM

    I think in the first reaction the salt had a stronger attraction to the water leaving no "bonding" site for the methanol. In the second reaction the supersaturated liquid when more substance added the solid became more in quantity and absorbed the liquid. (my thoughts on the process)

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  5. Donnie SheaMarch 24, 2010 at 8:05 PM

    http://preparatorychemistry.com/Bishop_supersaturated.htm
    Good site on supersaturated solutions
    As for my theory, I believe the salt absorbs much of the water, therefore the methanol can no longer dissolve in the water.

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  6. matt johnsonMarch 25, 2010 at 4:52 AM

    i believe exactly what donnie said that because the salt absorbed the water, the methanol wasn't able to mix with the water and just sat on top

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  7. Taylor AdkinsMarch 25, 2010 at 5:19 AM

    I believe that the salt bonds with water because salt is ionic and water is covalent.

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  8. Charlie FisherMarch 25, 2010 at 5:48 AM

    I believe that the methanol does not have a strong attraction to water, and therefore was separated from it during the stirring process. The salt replaced it and the methanol rose to the top because it is less dense than water.

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  9. Ryan DiazMarch 25, 2010 at 5:52 AM

    I think the salt took up the areas occupied by the methanol so that the salt water and methanol seperated.

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  10. Ben SmithMarch 25, 2010 at 5:54 AM

    http://www.stevespanglerscience.com/experiment/00000078

    Heres a good site on supersaturated solutions

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  11. Justin ScheunerMarch 25, 2010 at 5:56 AM

    here is a website talking about the sodium acetate demonstration. and i think they didnt mix because of the nonpolar and polar ends on each of the three substances.
    http://www.instructables.com/id/Crystallization-of-homemade-sodium-acetate/

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  12. H.HillMarch 25, 2010 at 8:06 AM

    I think that the water had the correct number of orbitals to bond with the salt.

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  13. Colby "Girlfraand" MabryMarch 25, 2010 at 7:44 PM

    good website on henry's law.
    http://dwb.unl.edu/Teacher/NSF/C09/C09Links/www.chem.ualberta.ca/courses/plambeck/p101/p01182.htm

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  14. Matt OriansMarch 26, 2010 at 4:39 AM

    here's a good video on effervescence:
    http://www.metacafe.com/watch/1550867/effervescence/
    And i think the attraction between the salt and the water forced them together while the methanol was less dense and not attracted to it.

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  15. joe "kitty" krebsMarch 26, 2010 at 4:50 AM

    http://www.protocol-online.org/biology-forums/posts/24672.html

    hey guys this is a good site about concentration protocol in lab settings and such

    ReplyDelete

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