13, 17, 21
Which part of the molecule is more rigid?
left box, right box
Schematically, the solid liquid crystal has molecules aligned in a repeating
pattern. In the liquid, order is lost. In the liquid crystal, there is still
orientational order. Phase transitions are observed at 21 and 45 degrees
In which region would the liquid crystal be the stable phase?
A, B, C
2, 4, 6
A, B, C
d isomer, l isomer, both
Demonstration: Use gloves and hands to show the mirror-image relationship:
Which X-ray diffraction pattern corresponds to the FCC structure?
Which of the above three band diagrams represents solid hydrogen?
A, B, C
To conduct the experiment, the gas is compressed in a so-called anvil. The anvil must be made of a material that is 1) strong enough to withstand high pressures and 2) transparent, so that the sample can be viewed while it is being squeezed. Which of the following materials is the best choice for the anvil material?
diamond, NaCl, graphite
If you could conduct a diffraction experiment on the hydrogen sample while it was being squeezed, what do you predict would happen to the spacing between diffraction spots as the atoms are placed under increasing pressure?
the spacing would increase
the spacing would decrease
the spacing would stay the same
0, 1, 2, 3
If the hexagon is compressed in the vertical direction, as shown in Figure B, is there a net dipole moment?
1, 2, 3
236. Dissecting a Polymerization Reaction
Polyethylene is formed when the molecule ethylene is polymerized. Approximately how many C-C single bonds are formed from n molecules of ethylene? [The instructor may want to draw approximately half a dozen H2C=CH2 molecules in a line, sketch electron movement with arrows, and draw the resulting alkane to help students visualize this process.]
For the net reaction
nC2H4(g) ---> -[CH2-CH2]-n(s)
What is the sign of S?
Given that a mole of C=C double bonds is worth approximately 600 kJ/mol and a mole of C-C single bonds is worth approximately 350 kJ/mol, what is the sign of H?
Does H or S drive this reaction?
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