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Chemical Bonding and Molecular Structure — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryChemical Bonding and Molecular Structure5 Marks
Question
What is meant by the term average bond enthalpy? Why there is difference in bond enthalpy of O–H bond in ethanol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$ and water?
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Answer

Average bond enthalpy is obtained by dividing total bond dissociation enthalpy by the number of bonds broken. All the identical bonds ina molecule do not have there are two but breaking of first, the second some change bond is used by total bond dissociation by the number of bond broken.
Average bond enthalpy $=\frac{502+427}{2}=464$
The bond are differentent because of differentent around oxygen atom.

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