To determine which compound has the strongest dipole moment, we need to consider both the molecular geometry and the electronegativity differences between the atoms in each molecule.
1. Carbon Tetrachloride ([tex]$CCl_4$[/tex]):
- Structure: Tetrahedral
- Electronegativity difference between C and Cl creates individual C-Cl bond dipoles.
- However, the tetrahedral shape is symmetrical, and the dipoles cancel each other out.
- Result: No net dipole moment (non-polar molecule).
2. Bromine Chloride (BrCl):
- Structure: Linear
- Electronegativity difference between Br and Cl creates a bond dipole.
- While this molecule has a dipole moment, it is moderate because the electronegativity difference is not extremely large.
- Result: Moderate dipole moment.
3. Silicon Dioxide ([tex]$SiO_2$[/tex]):
- Structure: In its most common form (quartz), [tex]$SiO_2$[/tex] is a network solid rather than a discrete molecule.
- In a linear molecular context, as two Si=O bonds (like CO2), the dipoles cancel each other.
- Result: No net dipole moment (non-polar molecule).
4. Phosphorus Trichloride ([tex]$PCl_3$[/tex]):
- Structure: Trigonal pyramidal
- The electronegativity difference between P and Cl creates bond dipoles.
- The molecular shape is asymmetrical, which means the dipoles do not cancel out completely.
- Result: Strong dipole moment.
5. Water ([tex]$H_2O$[/tex]):
- Structure: Bent (due to lone pairs on oxygen)
- The electronegativity difference between H and O creates bond dipoles.
- The bent shape means that the dipoles do not cancel each other out.
- Result: Very strong dipole moment due to the combination of shape and high electronegativity difference.
Given these analyses, the strongest dipole moment is found in the molecule with both a large electronegativity difference and an asymmetrical shape that prevents dipole cancellation. Water ([tex]$H_2O$[/tex]) meets these criteria best, as it has a strong dipole moment due to its bent shape and significant electronegativity difference between hydrogen and oxygen.
Therefore, the compound with the strongest dipole moment of the given options is:
e. [tex]$H_2O$[/tex]
