Identify the molecules that have a net dipole moment. Select all that apply: BF3 CCl4 (CH3)2O CH2Cl2 CO2
The Correct Answer and Explanation is :
Let’s evaluate each molecule for its net dipole moment based on its molecular geometry and electronegativity differences:
- BF3 (Boron Trifluoride):
- Geometry: Trigonal planar.
- The boron atom in BF3 is surrounded symmetrically by three fluorine atoms. While the B-F bonds themselves are polar due to the significant electronegativity difference between B and F, the symmetry of the molecule (due to its trigonal planar shape) cancels out the individual dipoles. As a result, BF3 has no net dipole moment.
- CCl4 (Carbon Tetrachloride):
- Geometry: Tetrahedral.
- CCl4 has four C-Cl bonds, and while these bonds are polar, the molecule’s symmetrical tetrahedral shape means the dipoles cancel each other out. This results in no net dipole moment.
- (CH3)2O (Dimethyl Ether):
- Geometry: Bent (due to lone pairs on oxygen).
- The molecule has two C-H bonds and one C-O bond, which is polar. Oxygen is more electronegative than carbon, so the C-O bond contributes to the dipole. The bent geometry causes the dipoles to not cancel out, and thus, (CH3)2O has a net dipole moment.
- CH2Cl2 (Dichloromethane):
- Geometry: Tetrahedral.
- CH2Cl2 has two C-H bonds and two C-Cl bonds. The C-Cl bonds are polar, and the molecule’s geometry prevents the dipoles from canceling out. Therefore, CH2Cl2 has a net dipole moment.
- CO2 (Carbon Dioxide):
- Geometry: Linear.
- The C=O bonds are polar, but because the molecule is linear and the dipoles are equal and opposite, they cancel out. Thus, CO2 has no net dipole moment.
Molecules with a net dipole moment:
- (CH3)2O
- CH2Cl2
I’ll also generate an image to visualize the molecular shapes of these molecules.
Here is the illustration showing the molecular structures of (CH3)2O, CH2Cl2, BF3, CCl4, and CO2 with their respective geometries and polar bonds. As we discussed:
- (CH3)2O and CH2Cl2 have a net dipole moment due to their bent or asymmetrical geometries that prevent the cancellation of dipoles.
- BF3, CCl4, and CO2 have no net dipole moment due to their symmetric molecular shapes.
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