Question

Which of the following statements is true about phosgene (COCl₂) molecule?

A. the bond angle Cl-C-Cl is 109.5° as the phosgene molecule is tetrahedral
B. the bond angle Cl-C-Cl is slightly smaller than the ideal 109.5° due to the lone pair on the carbon atom
C. the bond angle Cl-C-Cl is 120° as the phosgene molecule is trigonal planar
D. the bond angle Cl-C-Cl is slightly larger than the ideal 120° due to the C=O double bond
E. the bond angle Cl-C-Cl is slightly smaller than the ideal 120° due to the C=O double bond

Answer 1

The Cl-C-Cl bond angle in a phosgene (COCl₂) molecule is slightly less than 120° due to the higher electronegativity and the greater s-character of the C=O double bond, which causes a distortion from the ideal trigonal planar shape.

Step-by-step explanation:

The statement that the bond angle Cl-C-Cl is slightly smaller than the ideal 120° in a phosgene (COCl₂) molecule is true. This is because the C=O double bond is more electronegative than the C-Cl bonds, leading to greater s-character in the C=O bond and thus a greater pull of electron density towards oxygen.

This pulls the carbon atom slightly, leading to a reduction in the Cl-C-Cl bond angle from the ideal 120° that would be found in a perfectly trigonal planar geometry such as in the BCl₃ molecule, where all the bonds are identical and thus the bond angles are exactly 120°. In contrast, while the AX3 general formula would suggest 120° angles, the different electronegativities and bond strengths in COCl₂ result in a slight distortion of the trigonal planar shape.