Ch. 9 Flashcards
what is kinetics
the study of how rxns takes place and how fast they occur
what are elementary steps? what do they show
elem steps are a sequence of steps that show us reaction mechanism
what are between elementary steps?
intermediates: molecular entity that is formed from the reactants but is CONSUMED in further reactions in stepwise chemical reactions that contain multiple elementary steps
what is the rate of a rxn? what 3 things determine the rate?
rate: indicates how fast reactants are consumed or how fast products are being made
1. how freq molecules collide
2. orientation of collisions
3. their energy
what is the rate determining step
the step that determines the overall rate of rxn. the SLOWEST STEP ALWAYS
what is activation energy? if this is reached, what occurs?
activation energy is the minimum energy required of a reactant to proceed with creation of products. if this occurs, reactants go through short lived transitions states
what causes the rate to occur faster?
- lower activation energy
- greater conc of reactants
- higher the temp
what is a catalyst
makes rxn go faster by lowering activation energy and it is NOT CONSUMED (unchanged), and doesnt affect thermodynamic quantities
what does the rate law tells us? use A+B=C+D
it tells us the initial rates of rxn when reactant disappears. the only molecules that are involved in rate determining step. rate= K[A]^x [B]^x
how to find rate constant ?
K= rate/ [A][B]
transition state vs intermediate
transition state is energy maximum while intermediate is energy minimum but still higher than reactants and products
do catalysts lower Ea of both forward and reverse rxns?
yes
how to find rxn rate?
look at changes between experiments for the reactant youre finding the order with no changes in the other reactant. and find the proportion
when CAN you find the rate law
with experimental information, elementary step rxn, or a rate-determining rxn, NOT when given a random chemical eq
molecules must do what to react
collide with each other
