Rates of Reaction

Learn to always consider reactions in terms of a "decrease in reactants"or an "increase in products" obviously with respect to concentration and the presence of catalysts... helps to think of rate laws and rate-determining steps faster.

5 factors that affect rate: 1) concentration of reactants, 2) temperature, 3) presence of catalyst, 4) rxn medium, 5) surface area of reactants
Observing rate change from physical properties:
(1) COLOR -- measure change in absorption of electromagnetic radiation
(2) Change in PRESSURE w/ gases -- change in number of gaseous molecules

Reaction: aA + bB →(C)→ dD + eE

Rate Law = k [A]^m [B]ⁿ [C]^p

*** DO NOT WRITE THE CO-EFFICIENT for the exponents… they are EXPERIMENTALLY DETERMINED and must be derived from calcuculating the rate order from a table of trials!!!

Caluclating Rate Order:
1. Find trials in which target conc. [A] changes and other conc. variables [B] and [C] stay the same.
2. Note how the rate changes for those 2 trials, and deduce order from rate change:

Rxn order (m):	Rate mult. by:
-1	½
0	1
1	2
2	4

3. Solve for k by plugging in data from ONE trial into the "rate law equation"
Arrhenius Equation: dependence of reaction rate on TEMPERATURE.

k = A e^{-Ea / RT}