Given the following average bond energies: C=O (double bond): 799 kJ/mol, C=S (double bond): 573 kJ/mol, and O=S (double bond): 523 kJ/mol, what is the apparent bond energy of the carbon–sulfur bond in carbonyl sulfide (COS)?

• A. 799 kJ/mol
• B. 523 kJ/mol
• C. 350 kJ/mol
• D. 573 kJ/mol

Answer: (D)

Verified step by step guidance

1. Identify the bonds present in carbonyl sulfide (COS). COS has a carbon atom double bonded to sulfur (C=S) and sulfur double bonded to oxygen (S=O).
2. Understand that the problem provides average bond energies for C=O, C=S, and O=S double bonds, and asks for the apparent bond energy of the carbon–sulfur bond in COS.
3. Recognize that the apparent bond energy of the C–S bond in COS corresponds to the average bond energy of the C=S double bond, since COS contains a C=S bond rather than a C–S single bond.
4. Use the given average bond energy value for the C=S double bond, which is 573 kJ/mol, as the apparent bond energy of the carbon–sulfur bond in COS.
5. Confirm that this value makes sense by comparing it to the other given bond energies: it is lower than the C=O double bond energy (799 kJ/mol) and higher than the O=S double bond energy (523 kJ/mol), consistent with the nature of the bonds.