reaction kinetics Flashcards
define rate of reaction
it is the change in amount or concentration of a reactant or a product per unit time
units of rate of reaction?
mol dm^-3 s^-1
for a single step hypothetical reaction:
aA + bB –> cC, rate of reaction is…
-1/a(dA/dt) = -1/b(dB/dt) = 1/c(dC/dt)
what is the rate equation
rate = k (A)^m (B)^n
what is the rate constant?
it is the proportionality constant for a given reaction at a certain temperature.
what is the Arrhenius equation?
Ae^(-Ea/RT)
what is a zero order reaction?
if it is a zero order reaction with respect to A, the rate equation is
rate = k[A]^0 = k
this means that the rate is independent of [A]
what is a first order reaction?
if it is a first order reaction with respect to A, the rate equation is
rate = k[A]^1 = k[A]
this means that the rate of the reaction is directly proportional to [A].
what is a second order reaction?
if it is a second order reaction with respect to A, the rate equation is
rate = k[A]^2
this means that the rate of the reaction is directly proportional to [A]^2.
what is half-life?
it is the time taken for the concentration os a reactant to be halved
what is a unique feature of a first order reaction?
the half-life of that particular reactant is constant
formula for half-life?
t1/2 = ln 2/k
how to obtain half life from a concentration graph?
look at the time it takes for the original [reactant] to be halved. then after that look at the time it takes for [reactant] to reach 1/4 of the original concentration. if the half life is constant, that reaction is first order.
