KA 3: kinetics Flashcards
what does the rate of a chemical reaction normally depend on?
concentration of the reactants
what are orders of reactions used to relate?
a reaction to the reacting species
changing the concentration of a reactant A has no effect on the reaction. Therefore:
reaction is first order with respect to A
doubling concentration of a reactant A doubles rate of reaction. Therefore:
how can it be expressed?
reaction is first order with respect to A
rate = k[A]
what does each component mean in rate =k[A]?
k = rate constant
[A] = the concentration of reactant A in mol l-1
if doubling the concentration of a reactant A increases the rate of reaction fourfold, then:
how is it expressed?
reaction is second order with respect to A
rate =k[A]^2
what is the order of a reaction (with respect to any one reactant)?
the power to which the concentration of that reaction is raised to in that equation
what is the overall order of a reaction?
sum of powers to which the concentrations of the reactants are raised in the rate equation
what can the order of a reaction only be determined from?
experimental data
how can the rate equation and rate constant (including units) be determined?
from initial rate data for a series of reactions in which initial concentrations of reactants are varied (can be 0,1st,2nd or 3rd order)
how can reactions usually occur?
by a series of steps called a reaction mechanism
what is the rate of a rate dependent on?
slowest step (rate determining step)
what can experimentally determined rate equations be used to determine?
possible reaction mechanisms
what is meant by the order of a reaction?
the number of moles of reactants involved in the rate determining step
