William C. answered • 09/21/23
Experienced Tutor Specializing in Chemistry, Math, and Physics
In the figure, potential energies (PE) are
reactants (A + B): 40 kJ
transition state: 100 kJ
products (C + D): 20 kJ
The activation energy is ___ kJ
The activation energy is transition state energy – reactant energy = (100 – 40) kJ
This is not asked in the question, but note that
activation energy determines the rate of the reaction (how fast it takes place)
lower activation energy means a faster reaction
higher activation energy means a slower reaction
______________________________________________________________
The reaction is _____ (endothermic or exothermic).
The overall change in potential energy (ΔPE) is
ΔPE = product energy – reactant energy = (20 – 40) kJ
When products are more stable (lower PE) than reactants (higher PE)
ΔPE is negative and the reaction is exothermic
When products are less stable (higher PE) than reactants (lower PE)
ΔPE is positive and the reaction is endothermic
