Final answer:
To estimate the C≡O bond energy in CO(g), we use the provided enthalpy change of -748 kJ and known bond energies from the formation of CO2 to set up an equation. By substituting the enthalpy change and solving for the unknown C≡O bond energy, using the bond energy value of C=O in CO2, we can estimate it. Discrepancies may arise due to mean bond enthalpies being averages that may not perfectly match individual molecules.
Step-by-step explanation:
To estimate the C≡O bond energy in CO(g) using the given enthalpy change for the reaction, we need to compare the enthalpy change of the reaction to the bond energies of the reactants and products. The reaction in question is the formation of CO2 from CO and O2, and the provided enthalpy change is -748 kJ for the conversion of CO to CO2.
The general approach to estimate the C≡O bond energy involves using the provided enthalpy change and the known bond energies in the reaction. Since the reaction of converting CO to CO2 involves breaking the C≡O bond in CO and forming two C=O double bonds in CO2, we can write an equation that relates the enthalpy change to the bond energies involved:
ΔH (reaction) = Bonds broken - Bonds formed
The bonds formed are two C=O double bonds, and if we denote the bond energy of the C≡O bond in CO as x, the equation becomes:
-748 kJ = x - 2 × bond energy of C=O
The bond energy for C=O in CO2 is typically around 799 kJ/mol per bond. Therefore, we get:
-748 kJ = x - 2 × 799 kJ/mol
By solving for x, we can estimate the C≡O bond energy in CO(g).
Note that the experimental value for this reaction's enthalpy change is −802.4 kJ/mol, which is slightly different from the provided -748 kJ. This discrepancy is attributed to the use of mean bond enthalpies, which are average values and can differ slightly from the actual bond energies in a specific molecule.