Which of the following best describes bond dissociation energy?

• A. The energy required to ionize one mole of atoms in the gas phase.
• B. The energy needed to convert a solid into a gas.
• C. The energy released when a bond is formed between two atoms.
• D. The energy required to break one mole of a specific bond in a gaseous molecule.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the concept of bond dissociation energy (BDE). It refers to the amount of energy required to break a specific chemical bond in one mole of gaseous molecules, resulting in the separation of atoms or radicals.
2. Step 2: Recognize that bond dissociation energy is an endothermic process, meaning energy must be absorbed to break the bond, unlike energy released when bonds form.
3. Step 3: Differentiate bond dissociation energy from other energy terms: ionization energy is the energy to remove an electron from an atom or ion, and enthalpy of vaporization is the energy to convert a solid or liquid into a gas.
4. Step 4: Note that bond dissociation energy is usually measured in units of kJ/mol and is specific to each type of bond in a molecule, reflecting bond strength.
5. Step 5: Conclude that the best description of bond dissociation energy is 'the energy required to break one mole of a specific bond in a gaseous molecule,' as it precisely captures the definition and context of BDE.