What determines the rate of a chemical reaction?

There are several factors that can affect the rate of chemical reactions:

concentration of reagents. A higher concentration of reactants leads to more efficient collisions per unit of time, which leads to an increase in the reaction rate.
temperature. Usually, an increase in temperature is accompanied by an increase in the reaction rate.
state of matter. The rate of a chemical reaction depends on the environment in which the reaction takes place.
the presence of catalysts. Catalysts (for example, enzymes) lower the activation energy of a chemical reaction and increase the rate of a chemical reaction.