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Homework Help: Intermolecular bonding in liquids

  1. May 13, 2009 #1
    I have done an experiment in which I measured the time and depth of the vortex of water, paint thinner (varsol), and vegetable oil. Water had the deepest and longest lasting vortex, paint thinner was a little less, then oil had a very minimal vortex that was gone right away.

    Now I'm trying to answer the following questions, but am not sure if I am on the right track...I know some other posts have somewhat addressed this, but I would like a better explanation.

    1. Name the types of intermolecular bonding present in each of the liquids.
    2. In terms of intermolecular bonding, explain the relative differences in time taken for the vortex to disappear in each liquid.
    3. Why is water so much different from the other 2 in time and depth of vortex?
    4. Why would sugar dissolve in water faster than salt (w/ same agitation and temp.)?

    This is what I have:

    1. The types of intermolecular bonding present in each of the liquids are:
    o van der waals forces – paint thinner
    o hydrogen bonding – water
    o dipole-dipole bonding – vegetable oil

    2. ?

    3. Water is so much different in terms of time and depth of vortex, because it is a smaller molecule. Since it is a smaller molecule, you can tranfer kinetic energy to it more easily. The water is able to gain more momentum, and thus the depth of the vortex is greater and takes longer to disappear. Oil contains oleic acid, which is a larger molecule, making it more difficult to transfer kinetic energy to. Paint thinner contains small molecules like toluene (which is still bigger than a water molecule), which is why it is between water and oil in terms of time and depth of vortex.

    4. With the same type of agitation and at the same temperature, sugar dissolves faster in water than salt because sugar is covalently bonded while salt is contains ionic bonds. The covalent bonds in sugar make sugar molecules weaker, and the ionic bonds in salt make them stronger and harder to separate. A greater number of bonds are able to form between sugar and water compared to salt. This is because the salt ions are smaller compared to the size of the sugar molecules. Sugar has a greater solubility than salt.
  2. jcsd
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