Question

Rank the following molecules in order of increasing dipole moments: bcl3 , bcl2h , bclh2.

Answer 1

The molecules BCl3, BClH2, and BCl2H can be ranked in increasing order of dipole moments based on molecular symmetry and differences in electronegativity. BCl3 has no dipole moment due to its symmetrical shape, whereas BClH2 and BCl2H are not symmetrical and have nonzero dipole moments, with BCl2H having the highest due to having more polar B-Cl bonds.

Step-by-step explanation:

Ranking the molecules BCl3, BCl2H, and BClH2 in order of increasing dipole moments involves understanding both molecular geometry and electronegativity differences. For BCl3, the molecule is trigonal planar and symmetrical, which means any dipole moments from the B-Cl bonds cancel out, resulting in a net dipole moment of zero. In the case of BCl2H and BClH2, we need to compare the difference in electronegativity between B-Cl and B-H bonds as well as the molecule's geometry. The electronegativity difference between boron and hydrogen is smaller (2.04 for B and 2.20 for H) compared to boron and chlorine (3.16 for Cl), which makes B-H less polar than B-Cl.

Furthermore, the molecular geometry for BCl2H and BClH2 is no longer symmetrical, leading to a net nonzero dipole moment for both. The molecule with more B-Cl bonds will have a higher dipole moment due to the greater polarity of the B-Cl bond compared to the B-H bond. Thus, we can rank the molecules in order of increasing dipole moments as: BCl3 < BClH2 < BCl2H.

Answer 2

BCl₃ has no net dipole moment due to its symmetrical structure. Replacing Cl with H in BCl₃ creates a net dipole as BCl₂H and BClH₂ have increasingly asymmetrical structures, leading to BClH₂ having the highest net dipole moment.

Step-by-step explanation:

• The student is asking to rank the molecules BCl3, BCl₂H , and BClH₂ in order of increasing dipole moments.
• The molecule BCl₃ is trigonal planar and symmetrical, hence it has no net dipole moment because the individual dipoles cancel out.
• As we substitute Cl atoms with H atoms, the symmetry is broken, resulting in a net dipole moment.
• Electronegativity plays a critical role in determining the magnitude of the dipole moment.
• Since Cl is more electronegative than H, replacing a Cl atom with an H atom in BCl₃ increases the dipole moment due to the increased difference in electronegativity between Boron (B) and the surrounding atoms.

Therefore, we rank them as follows in order of increasing dipole moments:

1. BCl₃ (no net dipole moment)
2. BCl₂H
3. BClH₂(highest net dipole moment)