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Which out of NH_(3) and NF_(3) has higher dipole moment and why ? |
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Answer» SOLUTION :The dipole moment of `NH_(3) ` is more than `NH_(3)`. Dipole moment of `NH_(3) = 1.47 D = 4.9 xx 10^(-30)` C m Dipole moment of `NF_(3) = 0.23 D = 0.8 xx 10^(-30)` C m `mu (NH_(3)) gt mu (NF_(3)) : ` Both the molecules have pyramida shape with a lone pair of electrons on nitrogen atom.  Electronegativity: H (2.1), N (3.0) and F (4.0) os, partially N NEGATIVE in `NH_(3)` but positive in `NF_(3)`. In case of `NF_(3)` the orbital dipole due to lone pair is in the same direction as the RESULTANT dipole moment of the N - H bonds where as in `NF_(3)` the orbital dipole is in the direction opposite to the resultant dipole moment of the three N - F bonds. The orbital dipole because of lone pair decreases the effect of the resultant N - F bond moments. Which results i the low dipole moment of `NF_(3)` as represented below. 
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