Supplemental Instruction
Iowa State University / Leader: / Ryan Gale
Course: / Chem 177
Instructor: / Miller/Bonaccorsi
Date: / 12/4/12
1) Moving from solid to liquid to gas, how do the following parameters change as the states moves in this order?
a.) Kinetic energy
b.) Temperature.
c.) Volume
d.) density
2) As intermolecular forces become stronger between atoms and molecules, more energy is needed to separate them. What trend is seen for heat of vaporization and the boiling point?
3.) Out of all the intermolecular forces, which are the strongest and which are the weakest?
4.) Given a description of an intermolecular force, name it and show an example of each:
a.) If a molecule has a dipole moment and it interacts with another molecule with a dipole moment, what kind of IMF occurs?
b.) If a molecule consists of a very electronegative atom and hydrogen, and that molecule interacts with another molecule of the same nature, what kind of IMF occurs?
c.) If a molecule is polar and encounters an ion in solution, what kind of IMF occurs?
d.) If a solid consists of a metal and a nonmetal, what kind of IMF exists between the atoms of the solid?
5.) Arrange substances CCl4, Si, and Ar in order of increasing boiling point.
6.) Benzoic acid, C6H5COOH, melts at 122°C. The density in the liquid state at 130°C is 1.08 g/cm3. The density of solid benzoic acid at 15 °C is 1.266 g/cm3.
a.) In which of these two states is the average distance between molecules greater?
b.) Explain the difference in densities at the two temperatures in terms of the relative kinetic energies of the molecules.
7.) Which type of IMF accounts for each of these differences?
a.) CH3OH boils at 65°C; CH3SH boils at 6°C.
b.) Xe is liquid at atmospheric pressure and 120 K, whereas Ar is a gas under the same conditions.