# How can I read the potential energy diagrams when there is thermal energy?

If you compare the size of the barrier to the average thermal energy, the probability of surmounting the barrier of height ${E}_{A}$ is approximately equal to the Boltzmann factor $P = \exp \left(\frac{- {E}_{A}}{R T}\right)$. So the probability of surmounting a 200 kJ/mol barrier at 500K is $1.3 \times {10}^{- 21}$ (really small!). That's why many reactions require ${10}^{20}$ attempts or more to get a successful reaction event.