The bond length of a carbon–carbon single bond in ethane, C₂H₆
CHEMISTRY · Multi-part · CBSE · Chemistry · Chemical Bonding and Molecular Structure · Chemical Bonding and Molecular Structure
Problem
The bond length of a carbon–carbon single bond in ethane, C₂H₆, is reported to be 154 pm, and its average bond energy is 348 kJ mol⁻¹.
Answer the questions below about other carbon–carbon bonds.
(a) Predict an approximate numerical value (in picometres) for the equilibrium bond length of the carbon–carbon double bond in ethene, C₂H₄. Explain your reasoning.
(b) Predict an approximate numerical value (in picometres) for the equilibrium bond length of the carbon–carbon triple bond in ethyne, C₂H₂. Explain how your prediction is consistent with the trend in part (a).
(c) Using the information given above for the C–C single bond, estimate the average bond energy (in kJ mol⁻¹) for the C=C bond in ethene. State any proportionality or assumption you invoke.
(d) Using your answer to part (c), estimate the average bond energy for the C≡C bond in ethyne. Discuss at least one limitation of the assumptions made in parts (c) and (d).