Exam Two Vocabulary Flashcards
integrated rate laws
relate concentration and time
half life
time required for the reaction concentration to reach 1/2 its initial value
activation energy
energy barrier between reactants and products, minimum energy required for a successful collision
collision theory
- the rate of a reaction is proportional to the rate of reactant collisions
- the reacting species must collide in an orientation that allows contact between the atoms that will become bonded together in the product
- the collision must occur with adequate energy to permit mutual penetration of the reacting species valence shells so that the electrons can rearrange and form new bonds (and new chemical species)
molecular orientation
function of reactant structure (geometry)
independent of temperature
reaction mechanisms
describes the interaction between reactants at the molecular level, explains the rate law, describes the overall reaction as a series of collisions (elementary steps)
molecularity
describes the number of participants in a collision = number of reactants in an elementary step
rate determining steps
slowest step in a reaction mechanism, determines overall reaction rate
rate law for the rate limiting step is the rate law for the overall reaction
determining reaction mechanisms
based on the observed/experimentally determined rate law
mechanisms have ONLY elementary steps
sum of steps = overall reaction
catalysis
substance that increases the reaction rate but does not change the overall reaction
types of catalysts
homogeneous catalyst and heterogenous catalyst
homogeneous catalyst
catalyst is in the same place as reactants
heterogenous catalyst
catalyst is in a different phase than reactants
mechanisms of catalysts
increase rate by changing reaction mechanism
form a lower E transition state
lowers Ea
