Question

The rate law for an elementary process can be written from the stoichiometry of the reaction.
A.True
B.False

Answer 1

Basically, rate law which is also known as rate equation for a chemical equation is an expression which provides a relationship between the rate of reaction and the concentration of the reactant that are participating in it. Moreover, the expression of the rate law for a specific reaction can only be determined experimentally.

Complete step by step answer:
Generally, the elementary reactions are the sum to the overall reaction equation. The rate laws for the elementary steps are derived from the molecularity of each step. Now, the molecularity is defined as the number of reacting molecules which collide simultaneously to bring about a chemical reaction or it can also be defined as the number of reactant molecules taking part in the reaction.
Now, every chemical reaction proceeds according to a reaction mechanism which is further a step by step description of what occurs during a reaction on the molecular level. So, each step of the mechanism is known as an elementary process which describes the single moment during a reaction in which the molecules break and form new bonds.
Moreover, there are two requirements that must be fulfilled for a reaction mechanism to be valid. These steps are:
1.The sum of each elementary step in a reaction mechanism must yield the overall reaction equation.
2.The rate law of the rate determining step must agree with the experimentally determined rate law.
Therefore, the given statement is correct.
Hence, option A is correct.

Note: Usually the rate determining step is the slowest step in a reaction mechanism. It further determines the rate of the overall reaction because it is the slowest. Moreover, there are three possible molecularities i.e. unimolecular, bimolecular and termolecular. Generally, termolecular is not common due to the rarity of these molecules colliding at the same time.