Question

The bond length of $HCl$ molecule is $1.275\,\mathring{A}$ and its dipole moment is $1.03 \,D$. The ionic character of the molecule (in percent) (charge of the electron $=4.8 \times 10^{-10}$ esu) is

• A. 100
• B. 67.3
• C. 33.66
• D. 16.83

Answer 1

Answer: (D)

Given,

observed dipole moment $=1.03\, D$

Bond length of $HCl$ molecule, $d=1.275 \,\mathring{A}$

$=1.275 \times 10^{-8} \,cm$

Charge of electron, $e^{-}=4.8 \times 10^{-10}$ esu

Percentage ionic character $=$ ?

Theoretical value of dipole moment $=e \times d$

$=4.8 \times 10^{-10} \times 1.275 \times 10^{-8} esu - cm$

$=6.12 \times 10^{-18} esu - cm $

$=6.12\, D$

Percentage ionic character

$=\frac{\text { observed dipole moment }}{\text { theoretical value of dipole moment }} \times 100$

$=\frac{1.03}{6.12} \times 100$

$=16.83 \%$