Bond Enthalpy Flashcards
Define the term bond enthalpy
The energy required to break a particular covalent bond in one mole of molecule in a gaseous state.
Where is enthalpy stored in a molecule?
- Enthalpy is stored within chemical bonds.
- Bond enthalpy indicates the strength of a chemical bond in a gaseous molecule.
What does average/mean bond enthalpy mean?
In different environments, some bonds can have different strengths. e.g. C-H bonds can have different strengths if in CH3Cl than in CH4, as Cl atom affects the environment.
Average bond enthalpy indicates the strength of a typical bond.
Is bond breaking endothermic or exothermic?
Endothermic
Energy is needed to break bonds.
Is bond making endothermic or exothermic?
Exothermic.
Energy is released when bonds are made.
How can you use bond enthalpies to determine enthalpy change?
enthalpy required to break bonds - enthalpy required to make bonds
Which strength of bond enthalpies will break first?
Bonds with smaller bond enthalpies will break first.
What do low bond enthalpies indicate?
That a reaction will take place quickly.
What are the limitations of mean bond enthalpy?
- Values taken from range of different compounds
- Based on gaseous compounds - less accurate for solids, liquids & solutions
