Does COS (carbonyl sulfide) have a dipole moment? Choose the answer that best explains the reason for your choice.

• A. No, because the electronegativities of carbon, oxygen, and sulfur are identical, so the molecule is nonpolar.
• B. Yes, because COS is a bent molecule, which always leads to a dipole moment.
• C. No, because COS is a linear molecule and all linear molecules are nonpolar.
• D. Yes, because COS is a linear molecule with atoms of different electronegativities, resulting in an uneven distribution of charge.

Answer: (D)

Verified step by step guidance

1. Step 1: Determine the molecular geometry of COS. COS is a triatomic molecule with the atoms arranged in a straight line, so its geometry is linear.
2. Step 2: Consider the electronegativities of the atoms involved: carbon (C), oxygen (O), and sulfur (S). These atoms have different electronegativities, with oxygen being the most electronegative, sulfur less so, and carbon intermediate.
3. Step 3: Analyze the bond dipoles. Because the atoms have different electronegativities, the C=O bond and the C=S bond each have a dipole moment pointing toward the more electronegative atom.
4. Step 4: Since the molecule is linear, the dipole moments from the two bonds do not cancel out completely because the magnitudes of the dipoles are different due to the different atoms involved.
5. Step 5: Conclude that COS has a net dipole moment because it is linear but composed of atoms with different electronegativities, leading to an uneven distribution of charge and thus a polar molecule.