How many of the following molecules possess dipole moments : #BH_3, CH_4, PCl_5, H_20, HF, H_2#?

1 Answer
Sep 9, 2017

Answer:

Only #H_2# and #PCl_5# possess no dipole moments....

Explanation:

The molecular dipole moment, is the VECTOR sum of the individual bond dipoles. For trigonal planar #BH_3# (an hypothetical species), and #CH_4#, and #PCl_5# the individual bond dipoles sum to ZERO. And of course there is no polarity to be considered in the the dihydrogen molecule....

For #H_2O# and #H-F# there is bond polarity, i.e. #""^(delta+)H-stackrel(delta-)O-H^(delta+)#, and #""^(delta+)H-F^(delta-)#, and because the individual bond dipoles do not SUM to ZERO...both the acid and the water are polar molecules.

#"Chloroform"#, #CHCl_3#, has some polarity, however, #"carbon tetrachloride"# is a non-polar molecule given that the #""^(delta+)C-Cl^(delta-)# dipoles sum to zero given a tetrahedral geometry.