3rd Quarterly AP Chem

kinetics

the study of rates of reactions

collision theory

particles must collide with an amount of energy equal to or greater than the activation energy, and must have the correct orientation

activation energy

minimum amount of energy to initiate a chemical reaction

reaction rate

the change in the concentration of a reactant or product with time

How to calculate rate of formation:

(1/coefficient)(rate)=(1/coefficient)(rate)

methods of increasing reaction rates (name 4)

increase surface area, increase M, increase temperature, add a catalyst

order of a reaction

add exponents in rate law

zero order reaction graph

linear when t vs. [A]_t

first order reaction graph

linear when t vs. ln[A]_t

second order reaction graph

linear when t vs. 1/[A]_t

reaction mechanisms are made up of simpler … steps

elementary

intermediate

formed in an early step and used in a later step; don’t appear in the overall balanced equation

molecularity

number of molecules in an elementary step (unimolecular, bimolecular, termolecular)

rules for writing reaction mechanisms:

sum of steps must give overall balanced equation, rate determining step should have the same rate law

rate-determining step

slowest step

catalyst in reaction mechanisms

used but never consumed; reactant of first step and product of last

equilibrium is reached when:

the rates of the forward and reverse reactions are equal the concentrations of reactants and products are constant

if K is greater than 1,

equilibrium is at the right and favors products

if K is less than 1,

equilibrium lies to the left and favors reactants

substances that don’t affect equilibrium

solids and pure liquids

homogenous equilibrium

reactants and products are in the same phase

heterogenous equilibrium

reactants and products are in different phases

finding k if a reaction is the sum of several reactions:

multiply the Ks of the separate reactions

finding k for the reverse reaction:

the reciprocal of K for the forward reaction

if the equation is multiplied by a number:

K is raised to the number

Q

initial concentrations in K expression

if Q < K,

system shifts right to reach equilibrium

if Q=K,

system is at equilibrium

if Q>K,

system shifts left to reach equilibrium

Le Chatelier’s Principle

stress shifts a system