# Validity of the law of mass action in three-dimensional coagulation processes

The speed of chemical reactions is constricted by the time it takes for the molecules or atoms to meet. The law of mass action accounts for this fact, stating that the rate of an elementary reaction is proportional to the product of concentrations of the participating particles. By analyzing a mathematical model of bimolecular reactions, we have probed the validity of this law. We find that at sufficiently high concentrations, the law of mass action is violated. The deviations are attributed to many-particle effects.