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 electrons, $e^{-}=4.8 \times 10^{-10}$ 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
$=\frac{\text { observed dipole moment }}{\text { theoretical value of dipole moment }} \times 100$
$=\frac{1.03}{6.12} \times 100$
$=16.83 \%$