Reaction Kinetics Flashcards
definition of order of reactions
shows how the concentration of each reagent affects rate of reaction
definition of order of reaction with respect to a reactant
power to which the concentration of reactant is raised in the rate equation
describe reaction rate/concentration of reactant graph
straight across = 0
linear = 1
increasing = 2
describe concentration of reactant/time graph
linear down = 0
curve = 1
more decrease = 2
describe zero order
half life decreases
conc. doesn’t affect rate of reaction
describe first order
concentration of one reactants affects rate of reaction
half life is constant
describe second order
concentration of two reactants affects rate
half life increases
what is a rate constant
represents how fast a reaction is going in reaction
units for rate constant
mol
dm-3
s-1
how do you calculate rate
rate = k[X][Y]
how to calculate half life
0.693/k
what does rate equation show
reactants in rate determining step/slow step/making the intermediate for slow step
reaction mechanism
A → B (fast)
B + C → D (slow)
A → B (slow)
B + C → D (fast)
what is the rate eqn for
A → B (slow)
B + C → D (fast)
Rate = k[A]
what is the rate eqn for
A → B (fast)
B + C → D (slow)
Rate = k [A][C]
how can data be found to make rate constant
initial rates (measure each reactant) - slow
using data from course of reaction
- sampling
- continuous
what is the difference between sampling and continuous
sampling needs quenching to stop/slow reaction
continuous using physical property to be followed
definition of catalysis
increase the rate by providing alternative pathway for the reaction with lower activation energy
definition of heterogeneous catalysis
occurs when catalyst is at different phase to the reaction mixture.
definition of adsorption
the bonding to the surface by the strengthening of those bonds, the covalent bonds between reactants weaken.
describe an example of heterogeneous catalysis
iron in haber process
diffusion of nitrogen/hydrogen gas
adsorption: N2 and H2 to surface
reaction: adsorbed nitrogen and hydrogen atoms react on surface = NH3
desorption: bonds between ammonia and surface weaken and break
diffusion of ammonia away
how do transition elements work in catalytic converters
adsorption of nitrogen oxides and carbon monoxides
to nitrogen molecules and carbon dioxide molecules
definition of homogeneous catalysis
occurs when catalyst is at the same phase as reaction mixture
example of homogeneous catalysis
iodine-peroxodisulfate reaction
Fe3+ catalyst
how does Fe3+ work in iodine-peroxodisulfate reaction
reaction more likely to occur with opposite charges
check notes for equations
