Reaction Profiles - Chemical Bonds
Chemistry: AQA GCSE Higher, topic 5.1.8
Chemical Bonds
All chemical bonds have a "bond energy" that measures the strength of chemical bonds. By subtracting the total bond energies of the products from the total bond energies of reactants, we can see if a reaction is endothermic or exothermic.
Exothermic reactions
- Energy released by making bonds > energy required to break bonds.
- I.e. overall energy change of reaction < 0
Endothermic reactions
- Energy released by making bonds < energy required to break bonds.
- I.e. overall energy change of reaction > 0
Test yourself on Reaction Profiles - Chemical Bonds
Using the bond energies 432 kJ/mol (H-H), 142 kJ/mol (O-O) and 459 kJ/mol (O-H), what is the overall energy change for the reaction 2H2+O2→2H2O?
Bond energies in 2H2+O2→2H2O
Name the three types of bond found in the reactants and products of the reaction 2H2+O2→2H2O
Using the bond energy of a single H-H bond (432 kJ/mol), what is the total energy needed to break both H-H bonds in the reaction 2H2+O2→2H2O?
Comparing bond energies in 2H2+O2→2H2O