Which of the following exhibits dipole-dipole forces as its strongest intermolecular force?
Question 1 options:
a) NH3
b) CH4
c) BCl3
d) CO2
e) H2
state why?
a) NH3
NH3 exhibits dipole-dipole forces as its strongest intermolecular force because it is a polar molecule. The ammonia molecule has a lone pair of electrons on the nitrogen atom and a partial positive charge on the hydrogen atoms. This asymmetrical distribution of charge creates a permanent dipole moment, resulting in dipole-dipole interactions between NH3 molecules.
The compound that exhibits dipole-dipole forces as its strongest intermolecular force is option a) NH3 (Ammonia).
Dipole-dipole forces occur between molecules with polar bonds. In NH3, the N-H bonds are polar because nitrogen (N) is more electronegative than hydrogen (H), causing a partial negative charge on the nitrogen atom and partial positive charges on the hydrogen atoms.
These partial charges create temporary attractions between the positive and negative ends of neighboring molecules. These dipole-dipole interactions are stronger in NH3 compared to the other options because NH3 has the strongest overall polarity among the given compounds.
To determine which of the given substances exhibits dipole-dipole forces as its strongest intermolecular force, we need to examine the molecular structure and polarity of each compound.
Dipole-dipole forces occur between molecules that have permanent dipoles. A molecule with a dipole consists of one or more polar bonds and an uneven distribution of charge, resulting in a positive and a negative end.
Examining the options:
a) NH3 (ammonia) - NH3 has a lone pair of electrons on nitrogen, creating a trigonal pyramidal molecular shape. It has a polar N-H bond, and the molecule itself is polar. Therefore, NH3 exhibits dipole-dipole forces.
b) CH4 (methane) - CH4 consists of four C-H bonds arranged tetrahedrally around the carbon atom. Since the four C-H bonds are symmetrically distributed, the molecule's dipole moments cancel out, resulting in a nonpolar molecule. CH4 does not exhibit dipole-dipole forces.
c) BCl3 (boron trichloride) - BCl3 has a trigonal planar molecular shape with three polar B-Cl bonds. However, due to the symmetry of the molecule, the individual dipole moments cancel out, resulting in a nonpolar molecule. BCl3 does not exhibit dipole-dipole forces.
d) CO2 (carbon dioxide) - CO2 consists of two polar C=O bonds that are linearly arranged. However, the dipoles of the two C=O bonds are in opposite directions and cancel each other out. As a result, CO2 is a nonpolar molecule and does not exhibit dipole-dipole forces.
e) H2 (hydrogen gas) - H2 consists of two hydrogen atoms bonded together. Since the two hydrogen atoms are the same and have similar electronegativities, the molecule is nonpolar. H2 does not exhibit dipole-dipole forces.
Based on this analysis, the substance that exhibits dipole-dipole forces as its strongest intermolecular force is:
a) NH3 (ammonia)
This is because NH3 has a polar bond due to the difference in electronegativity between nitrogen and hydrogen, and the molecule itself is polar due to the trigonal pyramidal molecular shape. As a result, NH3 exhibits dipole-dipole forces.