Intermolecular Forces Stations by ashrafp


									                              Intermolecular Forces Stations (IMFS)
Directions are located on each lab table. Work in any order.
    1. In a picture or words, describe the behavior of the water with the charged balloon.

    2. By charging the balloon, you are collecting electrons on the side of the balloon that was rubbed, almost like making
       a gigantic induced dipole. Use this info, along with the fact water is a polar molecule, to explain which part of the
       water molecule is attracted to the balloon. Your explanation is at the particle level. Use words or a LABELED
       drawing, with the explanation including how the polarity of the water affects its behavior with the balloon.

    3. What type of IMF holds the water molecules together?

    4. What type of IMF combination is attracting the water to the balloon?

   1. Use words or a labeled diagram to explain the macroscopic interaction between the salt (NaCl) and the charged

    2. What type of compound is sodium chloride (use bond type to classify)? Based on this information (and
       remembering that when the balloon is rubbed the electrons are collected on the rubbed side resulting in a gigantic
       temporary dipole), explain on a molecular level why this interaction would occur. Which part of the NaCl is attracted
       to the charged side of the balloon?

    3. The NaCl and charged side of the balloon are displaying what IMF attraction combination?

                                                      IMF Stations p. 1
Floating Chads (the term “hanging chad” became infamous in the Al Gore/George W. election when Florida used a hole-
punch method for its ballots. The circle of paper that is supposed to get punched out is the “chad” and when the punch
doesn’t actually separate the chad from the ballot its called a “hanging chad”. Little bit of history.)

    1. Examine the substance in the flask. How many layers is it composed of? _______

    2. Describe the orientation of the chads in the flask. One side of the chad is gray, the other side is white.

    3. Without opening the flask, and limited gentle shaking or tilting, try to get the chads to flip over (change orientation)
       and stay that way. What happens?

    4. The gray side, which is colored in pencil (graphite) which is just a bunch of molecules made of carbon is: polar or

    5. The liquids in the flask are water and mineral oil. Explain the IMF occurring in this flask. Include the polarity of
       each liquid, the polarity of each side of the chad, and the orientation of the chad to the liquids.

    6. The white side of the chads and the water share what type of IMF attraction? (may be a combo)

Green Funk
                                           Bottle A                                    Bottle B
Initial appearance (should be 2 layers
of a different color, if not then wait)

Appearance immediately after

Appearance 2 min after gentle tilting
(should be 2 layers)

                                                        IMF Stations p. 2
   1. Based on your knowledge of polarity AND DENSITY explain why the 2 layers separate. Keep in mind a polar
      molecules attraction for molecules like itself.

   2. Assuming the colorless liquid is the same in both bottles, do you think the green layer is also the same? Explain
      why or why not.

Liquid Art
    1. Describe the shape of each liquid on the wax paper—does it smear or remain a bead?

   2. Describe the movement of the green liquid—does it smear, remain a bead, follow the toothpick, join with other
      drops of the same liquid?

   3. Describe the movement of the yellow liquid—does it smear, remain a bead, follow the toothpick, join with other
      drops of the same liquid?

   4. After mixing a few drops of the green and yellow liquid, describe the interaction.

   5. Both drops are on wax paper, which is a nonpolar substance.
          a. Is the green liquid polar or nonpolar? Explain your logic.

           b. Is the yellow liquid polar or nonpolar? Explain your logic.

   6. Why didn’t the food coloring mix well with the yellow liquid? Explain by describing whether the food coloring and
      yellow liquid had similar or different IMFs. Remember—nonpolar substances can exert dispersion forces on one

                                                     IMF Stations p. 3
   7. One of the liquids remained a bead on the wax paper. Are the IMFs in this liquid stronger or weaker than the IMFs
      in the other liquid? Explain.

Mural Meany
   1. Which solvent dissolved the ink?

   2. Is the ink polar or nonpolar? Explain.

   3. Acetone is the main component of nail polish remover. Is nail polish polar or nonpolar?

   4. The dye of the candy coating of M&Ms melt in your mouth (and in your hand if hold them long enough). Are the
      dyes in the candy coatings polar or nonpolar? (hint: after dropping a few M&Ms in your Slurpee---yummy!—the
      candy coatings appear white b/c the dyes dissolve into the Slurpee)

Penny Stacker
   1. How many drops of oil fit on the head of the penny?

   2. How many drops of water fit on the head of the penny?

   3. Why were you able to fit more drops of __ on the penny than drops of __? Your response should include the
      concept of polar, nonpolar, IMF, dispersion forces in nonpolar molecules, and H-bonding.

Smear Races
  1. Which smear evaporated the quickest—ethyl alcohol, water, or acetone?

   2. Based on the evaporation rates, which substance has the strongest IMF? Weakest?

   3. Rank the liquids in expected order of decreasing melting and boiling points.

                                                    IMF Stations p. 4

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