Is CF2Cl2 a polar or nonpolar molecule?
The Correct Answer and Explanation is :
CF₂Cl₂ (Dichlorodifluoromethane) is a polar molecule.
Explanation:
Dichlorodifluoromethane (CF₂Cl₂) is a tetrahedral molecule, as it follows the geometry of methane (CH₄) but with fluorine (F) and chlorine (Cl) atoms replacing hydrogen (H). To determine its polarity, we must consider bond polarity and molecular shape.
1. Electronegativity Difference and Bond Polarity:
- Electronegativity measures an atom’s ability to attract electrons in a bond.
- The electronegativities of the atoms involved are:
- Carbon (C) = 2.55
- Fluorine (F) = 3.98
- Chlorine (Cl) = 3.16
- Since fluorine is much more electronegative than carbon, the C–F bonds are highly polar, with a significant dipole moment pointing toward fluorine.
- The C–Cl bonds are also polar, but with a smaller difference in electronegativity than C–F, leading to weaker dipoles.
2. Molecular Geometry and Dipole Moment:
- CF₂Cl₂ has a tetrahedral shape, with two fluorine and two chlorine atoms around the central carbon.
- If all four substituents were the same, the dipoles would cancel out, making the molecule nonpolar.
- However, fluorine is much more electronegative than chlorine, creating an asymmetric charge distribution.
- The dipole moments of the C–F and C–Cl bonds do not cancel completely, resulting in a net dipole moment.
3. Conclusion:
Due to the uneven distribution of electronegativity and the tetrahedral asymmetry, CF₂Cl₂ is a polar molecule. This polarity contributes to its properties, such as being a good solvent for nonpolar substances and its past use as a refrigerant (Freon-12).