1. Ch. 3. KINETIC VS. EQUILIBRIUM MODELING
3-1. Definitions
Kinetics?
Dealing with processes (reactions) as a function of time on a certain pathway – for a given infinite time, the reaction should reach an equilibrium state
Equilibrium?
A state in which there is no further apparent change (it becomes stable) due to the equal rate of forward and reverse process (reaction) – should be reversible
Modeling using either kinetics or equilibrium assumption in aqueous geochemistry.

2. Can you distinguish the following terms?
Equilibrium vs. Disquilibrium
Partial equilibrium
Local equilibrium

3. 3-2. Applicability of Kinetic or Equilibrium Modeling
Residence time (tR): The time for a substance to stay in the given system (see eqn. 2.5 in the text).
Half-life (or half time of reaction) (t1/2): The time required for half-completion of the process (reaction), assuming no reverse reaction and absence of initial products. (see eqn 2.6 in the text).
If tR >> t1/2: Equilibrium model applicable.
Otherwise, a kinetic model should be used.
Fig. 2.2 on p.54 for the various tR.
Table 2.1 on p.55 for reaction types and their t1/2.

4. 3-3. Kinetics Elementary vs. overall reactions
Order of an elementary reaction
Order of an overall reaction (determined by a stoichiometry  eqn 2.18, 2.19 on p. 57)
How to derive an kinetic equation? (in a differential equation form)
See Table 2.2 and Fig for the kinetic expressions of some reactions
Effect of T: Arrehnius equation (eqn 2.29, p.60)
See Ea values for various reactions on p. 62.

5. Assignments:
Read examples (from p.68 to 78), especially those corresponding to one’s thesis subject.
Solve the Problems
#2, #3, #4, #8