Exam3ReviewW2014 - CHEM162:Exam3StudyGuide...

CHEM 162 Exam 3 Review page 1 of 4
CHEM 162: Exam 3 Study Guide
CHAPTER 15: Chemical Kinetics
chemical kinetics: study of the factors that
influence reaction rates
reaction rate: a positive quantity expressing the
concentration change with time
Use experimental data given to
– determine a general reaction rate given
concentrations of reactants/products over time
– determine the rate of disappearance/
consumption of a reactant or rate of
appearance/production of a product given the
rate of disappearance/appearance of another
reactant/product in the reaction
Determine reaction rate
– Given experimental data of concentrations and
time.
Know the terms: rate law, rate constant (k)
Reaction Order :
– zero ‐ order, first ‐ order, second ‐ order
– Determine overall order for a reaction given rate
law.
Distinguish between the instantaneous reaction
rate and the average reaction rate .
Determine rate law using initial rates method
– Given data of concentrations and rates.
– Cannot be determined given only the balanced
chemical equation.
half ‐ life (t
1/2
): the time required for the
concentration of a reactant to decrease by half
Determine the reaction order given experimental
data of reactant concentration over time .
– Recognize the plots giving a straight line for
zero ‐ order, first ‐ order, and second ‐ order
reactions.
Determine the reaction order given experimental
data of reactant concentration over time
(Continued)
– Recognize that the half ‐ life is only constant for
first ‐ order reactions .
– Compare slopes for the first and last sets of data
to see if slope changes for each reaction order.
Do calculations given integrated rate laws for
zero ‐ order, first ‐ order, and second ‐ order
reactions.
– Solve for concentration at a given time given
initial concentration and rate constant.
– Carry out natural log (ln) calculations for 1 st ‐
order reactions—review your algebra!
– Solve for the time required for the
concentration to decrease to a given amount.
– Solve for half ‐ life given rate constant, k, or vice
versa.
COLLISION MODEL/THEORY: reactant molecules
must collide to react
Activation Energy (E
a
): minimum energy needed
for chemical reaction
Reaction Rate and Temperature
– As T  , reaction rate  since molecules move
faster and more molecules have activation
energy.