Answer:
1) Reaction rate, in chemistry, the speed at which a chemical reaction proceeds. It is often expressed in terms of either the concentration (amount per unit volume) of a product that is formed in a unit of time or the concentration of a reactant that is consumed in a unit of time.
2) By collecting the hydrogen gas that is produced over water or in a syringe, rate graphs can be produced. The volume of gas produced and the time taken need to be recorded. The rate of the same reaction could be monitored by measuring the change in the mass of reactants as they react to form products.