The bond energy (in kcal mol–1) of a C–C single bond is approximately
Bond energy is the energy required to break one mole of a specific chemical bond in the gaseous state. For a C–C single bond, this value is a well-established constant in chemistry.
The typical bond energy for a C–C bond is approximately: . Among the given options, 100 is the closest to this standard value.
Final Answer: 100
Bond energy is the amount of energy required to break one mole of a particular type of chemical bond in the gaseous state, separating the atoms completely. It is typically measured in kilocalories per mole (kcal mol–1) or kilojoules per mole (kJ mol–1). For a carbon-carbon (C–C) single bond, this value is a fundamental constant in organic chemistry.
The bond energy for a C–C single bond is approximately kcal mol–1 (or about kJ mol–1). This value represents the average energy needed to break such a bond, as the exact value can vary slightly depending on the specific molecule it is in (e.g., ethane vs. a longer-chain alkane).
Comparing this to the given options:
Therefore, among the choices, 100 is the closest approximation to the actual bond energy of a C–C single bond.
Bond energy, more precisely called mean bond enthalpy, is an average value. For example, the C–C bond in ethane (H3C–CH3) has a slightly different energy than a C–C bond in propane because the local chemical environment affects the bond strength. These values are crucial for calculating the enthalpy changes in chemical reactions using Hess's Law, where the reaction enthalpy is estimated from the sum of the energies of bonds broken minus the sum of the energies of bonds formed.
While there is no direct formula to calculate the bond energy of a specific bond from first principles (it is determined experimentally), it is used in the formula for estimating the enthalpy change of a reaction, :
Where represents the bond energy.