The reaction rate of a reaction can vary depending on a number of factors. The following are the most common ones that allow us to affect the rate of a reaction:

1. Reactant concentration

The reaction rate usually increases with the concentration of reactants. Though the specific mechanisms for this is actually complex, it's still intuitive, because more reactant molecules will be present to react with each other.

2. Temperature of the reaction mixture

Increasing the temperature of a system generally speeds up the chemical reaction. As the temperature is increased, the reactant molecules move faster and with higher energy. This makes them undergo the reaction more frequently, and as a result, the reaction rate increases.

Figure 1. This graph shows the concept of why increasing the temperature will increase the reaction rate. The proportion of molecules which will readily react is larger at a higher temperature.

3. The presence of catalysts

A catalyst is a substance that speeds up a reaction without undergoing a permanent chemical change itself. In the Arrhenius equation, this is interpreted as decreasing the activation energy (Ea) of the reaction.

4. The solvent in the reaction

The solvent can impact the reaction rate through its physical properties and molecular interactions with the reactants and products. The choice of solvent depends on other things than just the reaction rate though, for example solubility of the reactants and products. It is important to pick a solvent that is chemically suitable for the choice of an included catalyst as well.