Chemistry- finding percent ionic character

Question

A hypothetical molecule, X–Y, has a dipole moment of 1.90 D and a bond length of 117 pm. Calculate the percent ionic character of this molecule.

Answer 1

Hello Elisabeth,

 

Percent ionic character is a nice theoretical construct that is given by the formula

 

%I = (μ_observed/μ_ionic) × 100

 

where μ_observed is the measured dipole moment and μ_ionic is the theoretical dipole moment from the charge separation and the bond length.

 

If the charge separation is considered to be caused by one electron transferred from X to Y and the bond length is 117 pm

 

μ_ionic = (charge of one electron in coulombs)×(bond length in meters)/(3.356×10^-30) <- this last factor converts the units to Debyes.

 

Plug in your μ_observed and your calculated μ_ionic, and there you are!

 

Jim Scripko