A mathematical model is proposed to investigate the kinetics and equilibrium of homogeneous elementary first- and second-order chemical reactions. The dynamics is defined by the Monte Carlo method (MCM), with the Metropolis update, and the Ehrenfest urn model (EUM). MCM is an important step that accesses the kinetic and thermodynamic properties of the system, while the EUM defines the orders of the reactions studied in this work. The main parameters, such as temperature, the activation energy and the steric factor, were taken into account in the calculation of the transition probabilities between the reactants and products. It is thus possible to reproduce the kinetic profiles of the reactions and to evaluate the influence of temperature and the steric factor. Furthermore, it is possible to simulate the behaviour of the system by modifying the activation energy barrier, thus simulating a catalytic process. The effect of the addition of molecules was also investigated, with the system returning to a thermodynamic equilibrium condition after partial consumption of the added reactant, as predicted by Le Chatelier’s principle. All the simulated data are in agreement with the theoretical results present in physical chemistry textbooks.