Item 4 Question 1
For parts of the free-response question that require calculations, clearly show the method used and the steps involved in arriving at your answers. You must show your work to receive credit for your answer. Examples and equations may be included in your answers where appropriate.

The figure presents two Lewis electron-dot diagrams. In the first diagram, a C atom is surrounded by 4 pairs of electrons, each of which is shared with an H atom. In the second diagram, a C atom is surrounded by 4 pairs of electrons, each of which is shared with a C l atom. Each C l atom has 3 additional pairs of nonbonding electrons.
Answer the following questions about CH4
and CCl4
. The Lewis electron-dot diagrams for molecules of the compounds are shown above.

(a) Which compound has the higher boiling point? Justify your answer. The type(s) of intermolecular force(s) in both substances should be included in your answer.
(b) At 400K
both compounds are gases. At this temperature, which compound, CH4(g)
or CCl4(g)
, behaves more like an ideal gas? Justify your answer, including reasoning about both molecules.
(c) CCl4(l)
is placed in a previously evacuated container at 30°C
, and some of the CCl4(l)
evaporates. In the box below, draw a particulate diagram to show the species in the container after some of the CCl4(l)
has evaporated. The phases of the species should be indicated by the spacing and distribution of the particles in the diagram. Some of the species shown in the legend will not be used.