In this sub-section, we analyze different quantities of interest (QoIs) obtained from the solution of the master equation by separately relying on QCT-computed and SurQCT-predicted rate coefficients. To this aim, an isochoric and isothermal chemical reactor is simulated for the O 2 +O system at nine different translational temperatures, which include the five training temperatures (1, 500, 5, 000, 10, 000, 15, 000, 20, 000 K) and five test temperatures: 2, 500, 6, 000, 8, 000, 12, 000, 14, 000 K. All collision processes are considered in the master equation analysis, and both dissociating and recombining scenarios are studied. For the former, the initial internal heat bath temperature is set to 300 K with 95% molecules and 5% atoms. For the latter, the initial temperature is set to 5, 000 K with 1% molecules and 99% atoms. The evolution of the mole fractions of O 2 and O is plotted in Fig. for two recombining scenarios at heat bath temperatures of T = 1, 500 and 2, 500 K, and three dissociating scenarios at heat bath temperatures of T = 8, 000, 10, 000, and 20, 000 K. Fig. shows the evolution of the average rotational and vibrational energies of the O 2 molecule for the same five heat bath temperatures. The agreement in the mole fraction evolution and average rotational and vibrational energy is excellent for both the recombining and dissociating scenarios. Furthermore, the percentage delay of O 2 depletion/recombination is plotted in Fig. for different translational temperatures. This variable quantifies the delay/advancement in time for the SurQCT-based O 2 mole fraction to reduce by 50% its initial/final value (depending on whether it is a dissociating or recombining case) compared to the QCT-simulation. It is computed according to the following equation,