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What kind of intermolecular forces are present in the following compounds: #C Cl_4#, #CH_2Cl_2#, #CH_3OH#, #CO_2#, #SCl_4#, and #SCl_6#?

1 Answer
Aug 16, 2016

Warning! Long answer. Here's what I get.

You have to draw the Lewis structure of each molecule, use VSEPR theory to determine its shape, and then decide whether or not the bond dipoles cancel.

#"CO"_2# and #"CCl"_4#

CO2 and CCl4
(From www.peoi.org)

#"CO"_2# is a linear molecule with an #"O-C-O"# bond angle of 180°. The bond dipoles are equal and in opposite directions, so they cancel.

#"CO"_2# is a nonpolar molecule. Its strongest intermolecular forces are London dispersion forces.

#"CCl"_4# is a tetrahedral molecule with a #"Cl-C-Cl"# bond angle of 109.5°.

The two #"C-Cl"# bond dipoles in the plane of the paper have a resultant pointing to the right at an angle of 54.75° from the vertical.

The two #"C-Cl"# bond dipoles behind and in front of the paper have an equal and opposite resultant to the first.

Since the bond dipoles are equal and in opposite directions, they cancel.

#"CCl"_4# is a nonpolar molecule. Its strongest intermolecular forces are London dispersion forces.

#"CH"_2"Cl"_2#

preparatorychemistry.com

#"CH"_2"Cl"_2# has a tetrahedral shape. The two #"C-Cl"# bond dipoles have a resultant that bisects the #"Cl-C-Cl"# bond angle.

#"CH"_2"Cl"_2# is therefore a polar molecule, and its strongest intermolecular forces are dipole-dipole forces.

#"CH"_3"OH"#

#"CH"_3"OH"# has a highly polar #"O-H"# bond. The #"O"# atom has a high #δ^"-"# charge, and the #"H"# of the #"OH"# has a high #δ^+# charge.

employees.csbsju.edu

The #"O"# in one molecule is strongly attracted to the #"H"# in another molecule, and the #"H"# in one molecule is strongly attracted to the #"O"# in another molecule.

The strongest intermolecular force in #"CH"_3"OH"# is hydrogen bonding.

#"SCl"_4#

See-Saw
(From en.wikipedia.org)

#"SCl"_4# has a see-saw shape.

The two horizontal #"S-Cl"# bond dipoles cancel, but the downward-pointing dipoles reinforce each other.

#"SCl"_4# is a polar molecule, and its strongest intermolecular forces are dipole-dipole forces.

#"SCl"_6#

#"SCl"_6#is an octahedral molecule.

upload.wikimedia.org

Every #"S-Cl"# bond dipole has a partner pointing in exactly the opposite direction, so all bond dipoles cancel.

#"SCl"_6# is a nonpolar molecule, so its strongest intermolecular forces are London dispersion forces.