• Chemical Kinetics:
o Chemical Kinetics:
Study of rates at which reactants/products change during a
Includes study of factors that affect rate of reactions, and steps
involved as a reaction proceeds from reactants to products.
o Reaction Rate:
The change in concentration of a reactant or product per unit of
The units on reaction rate are concentration per unit of time, e.g.,
• Writing Rate Law Expressions for Reactions:
o 2 NO + O → 22NO 2
Rate law expression has the form: Rate = k [NO] [O ]2n
• Integrated Rate Laws:
o Deriving a rate law equation for the reaction
X ® Y + Z
and the value of k all from a single experiment in which the change in the
concentration of reactant “X” is determined at various times.
1. Plot [X] v. t; if straight, reaction is zero order
2. Plot ln [X] v. t; if straight, reaction is 1st order
Slope = k
3. Plot 1/ [X] v. t; if straight, reaction is 2 order
Slope = k
• HalfLife (t½):
o For a firstorder reaction:
t = 0.693/k
• PseudoFirst Order Reactions:
o All reactants but one are present at such high concentrations that they do
not change significantly during the course of reaction
o Reaction rate is determined by the concentration of the limiting reactant.
• Factors Affecting Reaction Rate:
o Concentration of reactants:
Increased frequency of collisions.
Defined by rate law.
o Energy of collisions: