Question

The dipole moment of BeF2 is zero, while that of H2O IS 1.85 D. account for this on the basis of their molecular structure

Answer 1

Explanation:

BeF2 has linear shape and hence its bond dipole cancels each other. But water has a bent structure

and hence its bond dipoles do not cancel each other. So it has a net bond dipole of 1.85D.

Answer 2

The dipole moment of $BeF_{2}$ is 0 while that of $H_2O$ is 1.85 D is because of the following reasons.

• The hybridization of $BeF_{2}$  is sp and hence it is linear in shape with Be as the centre atom.
• The polarity of each Be-F bond acts in opposite direction and it is linear, the effect gets cancelled out completely hence its dipole moment is zero.
• The hybridization of $H_2O$ is $sp^3$ and it has a bent shape due to two bonds and a lone pair.
• The polarity of each H-O bond is in opposite direction but as the angle between the bonds is not 180, the effect is not completely cancelled and hence the resultant dipole moment is 1.85 D.

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