Rate expression
rate = k[A]^x[B]^y
rate constant
k
overall order of reaction
x + y
order of reaction
either x (with respect to A) or y (with respect to B)
Order of reactions
zero-order: the concentration does not affect the reaction rate first-order: order of reaction = 1 (rate is proportional to concentration) second-order: order of reaction = 2
catalysts in activation energy
Alter a reaction mechanism by introducing a step with a lower activation energy
Reaction mechanism
A series of separate intermediate steps. All elementary steps summed together will give the overall balanced reaction.
heterogeneous reaction
a reaction involving reactants in two different phases
homogeneous reaction
a reaction whose reactants and products exist in a single phase
molecularity
the number of reactant particles involved in an elementary step
Unimolecular
describes a reaction that involves only one particle that goes on to form products
bimolecular
an elementary step in a reaction that involves two particles, either the same species or different, that collide and go on to form products
Relationship between reaction mechanism, order of reaction and rate-determining step
The slowest step in a reaction mechanism is known as the rate-determining step or the step with the highest activation energy
unit rate of reaction
mol dm-3 s-1
unit concentration
mol dm-3
Concentration-time graph zero order
Concentration-time graph first order
Concentration-time graph second order
rate-concentration graph zero order
rate-concentration graph first order
rate-concentration graph second order
Gradient of arrhenius graph
-Ea/R
y intercept (Arrhenius graph)
ln[A]
units in arrhenius equation
t = kelvin, Ea = J mol-1
What is A in the arrhenius equation
A = frequency factor (how many successful reactions occur)
What is your x value
1/T
What are the axis of an Arrhenius equation?
Y axis = ln k
X axis = 1/T