A.P. Exam Review

Regular Review Day 4

Big Idea #4Rates of chemical reactions are

determined by details of the molecular collisions.

Enduring Understanding AReaction rates that depend on temperature and other environmental factors are determined by measuring changes in concentrations of reactants or products over time.

Enduring Understanding BElementary reactions are mediated by collisions between molecules. Only collisions having sufficient energy and proper relative orientation of reactants lead to products.

Enduring Understanding CMany reactions proceed via a series of elementary reactions.

Enduring Understanding DReaction rates may be increased by the presence of a catalyst.

= rate =

rate constant

derived

definition:

Rate law can be written from molecularity

Lowers the Ea by making a new ______________

Why? Experimental

ly derived rate laws show that all reactions aren’t elementary

k = zpe-Ea/RT

k =ln k=

Relating [ ] vs. time

1st order: 2nd order:

0 order:

Ch. 12 A.P. Chem. Chemical Kinetics

Reaction Rates Mechanisms

-[ ]

time

Avg. Rates Instantaneous Rates

Slope of the line tangent at that moment

Rate Law

k [ ]x

experimentally

Method of initial rates

Constant rates

[ ]’s for certain substances high

Zero order in one substance

Compare runs with all but one [ ] constant

Integrated Rate Laws

ln[ ] = -kt + ln[ ]0

1/[ ] = kt + 1/[ ]0

[ ] = -kt +[ ]0

ln([ ]/[ ]0) = -kt

0.693/k 1/k[ ]0

[ ]0/2kt½

series of steps by which a reaction occurs

Elementary steps

Inter-mediates

RDS catalysts

mechanism:

Used in one step, produced in another

Produced in one step, used in another

with a new and faster

(dictates)

Speeds up a reaction without being consumed

collision theory

Effective collisions

enough energy

Break and make new bonds

transitional particle

activated complex

...seen on P.E. diagram

Proper orientation

Ae-Ea/RT

(-Ea/R)1/T + lnA

Arrhenius Equation(s)

order

Beta Radiation

Electron Capture

Alpha Radiation

________

________

________