Rate of a chemical reaction = change in concentration

change in time

Rate equation = rate law = k[A]^m[B]^n

where m, n are the orders of the reaction (not necessarily the stoichiometric coefficients of A and B)
m, n must be determined through experimentation
for any elementary step is defined by the reaction stoichiometry. The rate reactionof an elementary step is given by the product of the rate constant and the concentrations of the reacntants in that step.

ZERO ORDER: R=K AND THE RATE IS INDEPENDENT OF TIME

Order: the exponent to which a reactant's concentration is raised in the rate law

Total order: the sum of all the exponents in a rate law.

Half Life- time required for reactant concentration to decrease to 1/2 its initial value
Order Half-Life Expression

Zero Order: Dependent on Concentrations
half life = [A]0
2k

First Order: independent of concentrations
half life = .693
k

Second Order: Dependent on concentrations
half life = 1
[A]0k



Factors that Affect the Rate of a Reaction:
1) Surface Area (more surface =faster rate)
2) Temperature (higher temperature=faster rate) RULE OF THUMB: FOR EVERY INCREASE OF 10DEGREES = DOUBLE RATE
3)Concentrations of Reactants (higher concentration=faster rate)
4)Nature of Reactants

Energy of Activation (Activation Energy): energy barrier to get the reaction started
Catalyst: speeds up the reaction without being consumed by it (lowers the activation energy by giving an alternative reaction pathway)

Integrated Rate Laws

Zero Order:
[A(final)] - [A (initial)] = -kt


First Order
ln[A (final)] - ln[A (initial)] = -kt

Second Order
1/[A (final)] - 1/ [A (initial)] = kt

Linearized Arrhenius Equation

ln(k)= ln([A]) - E(activation) R=8.31 J/molK
RT T= in kelvins
slope= -E(activation)
RT

Two Point Equation: if you know E(activation) and K at one temperature (activation energy does not change with temperature) then you can find k at different temperature using following equation

Ln(k1/k2)= E(activation) ( 1/T1 - 1/T2)
R


Slowest step of a reaction = rate-determining step

Rate Equations for Elementary Steps

Elementary Step	Molecularity	Rate Equation
A --> product	unimolecular	rate= k [A]^1
A + A--> product	bimolecular	rate= k[A]^2
A + B--> product	bimolecular	rate= k[A]^1[B]^1
2A + B --> product	termolecular	rate=k [A]^2[B]^1

Intermediate: a substance that is produced in one step of a mechanism but is consumed in a later step.

Reaction Mechanism: the sequence of bond-making and bond breaking steps that occurs during the conversion of reactants to products during a chemical reaction. Reactions are usually broken up into elementary steps. Also the molecularity of each step is based on how many reactants there are.

reaction rate vs. specific rate constant:
reaction rate is dependent on concentration while specific rate constant is dependent on temperature


Collision Theory:

states that the rate of a chemical reaction is equal to the collision rate (a very large number) decreased by multiplying by an orientation factor and a minimum energy factor

Transition-State Theory:

looks at energy changes and geometric changes of molecules as they collide. during the collision process, kinetic energy is converted to potential energy. if this potential energy meets or exceeds the activation energy the reaction can occur. there is also change in the geometry of the reactants as they become products. the geometry somewhere in the middle of this conversion is called the transition state, and it occurs when the maximum kinetic energy has been converted to potential energy (at the top of the potential energy profile). the potential energy profile also indicates the heat of reaction.

Endothermic:

potential energy of products > potential energy of reactants
needs greater activation energy

Exothermic:

potential energy of reactants > potential energy of products
needs less activation energy