Rate Law and Rate Mechanism

Define the Rate Law and provide its’ formula

• The mathematical expression that allows calculation of reaction rate as a function of reactant concentration

• rate = k[A]^m[B]ⁿ

What do the different components of the Rate Law stand for?

• k: the RATE CONSTANT

• [A] and [B]: the CONCENTRATIONS of the reactants

• m and n: the ORDERS OF REACTION

How is the Rate Constant determined?

• determined experimentally and is unique for a single reaction at a specific temperature

Define the Order of Reaction

• the exponent used to describe the relationship between the initial concentration of a particular reactant and the rate of the reaction

Define the Total Order of Reaction

• the SUM of the exponents in the rate law equation

What is a Rate Mechanism?

• A series of elementary steps by which a chemical reaction occurs

What is an Elementary Step?

• a step involving one, two or three entity collision that cannot be explained by simpler reactions

What is a Rate Determining Step?

• the step in a reaction mechanism that determines the rate of the overall reaction; the SLOWEST step in a reaction mechanism

What is a Reaction Intermediate?

• a species that is neither a reactant nor a product but is formed and consumed during the reaction sequence

What are the requirements for a Rate Mechanism to be plausible? (2)

• Summing the elementary steps in  the reaction mechanism must give the overall balanced equation for the reaction

• The reaction mechanism must agree with the experimentally determined rate law