Answer:Be sure to answer all parts. Select the type(s) of intermolecular forces that exists between molecules (or basic units) in each of the following species:
(a) BrF
i. dipole-dipole forces
ii. dispersion forces iii. ion-induced dipole forces
iv. dipole-induced forces
(b) CH4
i. dipole-dipole forces
ii. dispersion forces
iii. ion-induced dipole forces iv. dipole-induced forces
(c) SO2
i. dipole-dipole forces
ii. dispersion forces
iii. ion-induced dipole forces
iv. dipole-induced forces
Answer:
a) BrF - i. dipole dipole forces
b) CH4 - Ii. dispersion force
c) SO2 - Both i. dipole-dipole forces and ii. dispersion forces
Explanation:
Since bromine and fluorine are both halogens, which is group VIIA on the periodic table. Since they are both non-metallic elements, the bonds between the fluorine atoms and the bromine atom are covalent.
Intermolecular forces however are related to the electronegativity differences (polarity) of the bonds and the molecular shape.
Let’s take a simple linear molecule with a high polarity – BrF.
F = 3.98, Br = 2.96
Difference = 1.02 The bond is polar covalent.
Dipole -dipole interactions occur when the partial charges formed within one molecule are attracted to an opposite partial charge in a nearby molecule.
Moreover the intermolecular forces in methane are dispersion forces. The electronegativities of C and H are so close that C-H bonds are nonpolar. There are no bond dipoles and no dipole-dipole interactions.
While So2 is an angular molecule and hence polar, dipole-dipole interactions work between its molecules along with London Dispersion Forces.
Note: Regarding Induced forces;
Induced-Dipole Forces - result when an ion or a dipole induces a dipole in an atom or a molecule with no dipole. These are weak forces.
Ion-Induced Dipole Force is a dipole attraction with a weak attraction that results when the approach of an ion induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species
Dipole-Induced Dipole Forces
A dipole-induced dipole attraction is a weak attraction that results when a polar molecule induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species.