FUNCHEM 17 - Molecularities of reactions, reaction mechanisms and reaction orders and the Arrhenius equation Flashcards
What is a reaction mechanism?
A reaction mechanism tells you the sequence of steps that leads to product formation.
What is an elementary step?
An elementary step is each step in an overall reaction.
Molecularity
Molecularity tells you the number of molecules reacting in an elementary step: - Unimolecular = 1 reactant - Bimolecular = 2 reactants - Termolecular = 3 reactants
What is the rate determining step?
The rate determining step is the slowest elementary step in a reaction mechanism. The RDS determines the reaction order.
What is unique about single step reaction mechanisms?
You can determine the reaction order from the stoichiometry from a single step reaction mechanism.
What is the difference between an endothermic reaction and an exothermic reaction?
An exothermic reaction releases energy during product formation, while an endothermic reaction requires energy for product formation.
What is activation energy?
Based off of Arrhenius’s work, activation energy is the minimum amount of energy required to initiate a chemical reaction.
What is the Arrhenius equation?
K = Ae -Ea/RT
K - Rate constant
A - Frequency Factor
e - exponential
Ea - activation energy
R - gas constant
T - temperature
Rewrite the Arrhenius Equation in graphical form.
lnk = -Ea/RT + lnA
lnk –> y
-Ea/Rt –> slope
lnA –> y-intcerpt (tells you frequency of collisions)
What is the gas constant?
8.314 J/mol x K
