CHEM 191 Lecture 15 Flashcards
what is the only term in the rate law that depends on temperature
k - therefore k is given for a certain temperature
what 3 factors affect the rate at which molecules react
collision rate
collision effectiveness
collision orientation
what two factors affect collision rate
higher concentration = more collisions
greater speed (kinetic energy which is related to temp) = more collisions
what is activation energy
the energy threshold for reaction to occur
what is molecularity
the total number of species involved in a single collision leading to reaction
what are the classifications of molecularity
unimolecular, bimolecular and termolecular (unlikely)
experiments show that an increase in T speeds up all reactions. what is the approximate rule of thumb for this
for every 10 degrees celsius rise in T, the rate doubles
what does temperature affect in a reaction
collision frequency and collision effectiveness
what is a transition state
the state that occurs at the top of the activation energy barrier that contains partially broken and formed but no complete covalent bonds
what happens after the transition state
the reaction either forms products (effective collision) or returns to reactants (ineffective collision)
what is the Arrhenius equation in log form
lnk = lnA - (Ea/RT)
what is the frequency factor (A) in the Arrhenius equation
a factor that indicates the frequency of collisions that are favourably orientated - this value change with temp and concentration
does activation energy change with temperature
no
