Answer:
The speed at which the reactants change to products over a given time.
Step-by-step explanation:
A chemical's reaction rate is the change in the concentration of a reactant or a product with time (in moles per second).
Remember that during a chemical reaction, reactants are converted to products. Or what is the same, products are formed at the expense of reactants. This can be represented:
reactants → products
Therefore, the progress of a reaction can be followed measuring the decrease in concentration of the reactants or the increase in concentration of the products.
According to the temperature and other parameters, the reaction rate can increase or decrease.