rate
It should be noted that just because a process is spontaneous does not mean that it occurs quickly. The rusting of iron is a spontaneous process that takes place over a long period of time. The combustion of gasoline in oxygen also a spontaneous process is extremely fast when provided with a spark, but gasoline can be stored in air for quite a while without spontaneously combusting. Thermodynamics predicts the direction in which a reaction will eventually proceed, but it does not tell us anything about the rate at which the reaction occurs. The rate of a reaction depends on many factors, including activation energy, temperature, concentration, and the presence or absence of a catalyst. Chemical kinetics focuses on the pathway between reactants and products, while thermodynamics considers only the difference between the initial and final states.