Separate: Chemistry and Extended Only
The following are two examples of substitution reactions. Only the reaction involving chlorine is a photochemical reaction.
Extended Only
Bond forming is exothermic, bond breaking is endothermic.
Explain the difference between an exothermic reaction and an endothermic reaction.
Separate: Chemistry and Extended Only
Use the bond energies to show that the following reaction is exothermic.
Bond energy is the amount of energy (kJ / mol) which must be supplied to break one mole of the bond.
Bond energies in kJ /mol
Cl–Cl +242
C–Cl +338
C–H +412
H–Cl +431
bonds broken energy in kJ /mol
...................... .............................
...................... .............................
total energy = .............................
bonds formed energy in kJ /mol
...................... .............................
...................... .............................
total energy = .............................
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