Chemical Kinetics & Catalysis
60 terms · page 3 of 3
Second-Order Reaction
Chemical Kinetics & Catalysis
L/(mol·s)
A reaction whose rate depends on the square of one concentration or on the product of two concentrations.
1/[A] = 1/[A]₀ + kt
Selectivity
Chemical Kinetics & Catalysis
Dimensionless
The ability of a catalyst to direct a reaction towards one particular product among several possible ones.
selectivity = desired product / total product
Steady-State Approximation
Chemical Kinetics & Catalysis
mol/L
The assumption that the concentration of a reactive intermediate stays essentially constant because it is consumed as fast as it is formed.
d[intermediate]/dt ≈ 0
Steric Factor
Chemical Kinetics & Catalysis
Dimensionless
The fraction of sufficiently energetic collisions that also have the correct spatial orientation for reaction.
p = A / Z
Temperature Coefficient
Chemical Kinetics & Catalysis
Dimensionless
The factor by which a reaction rate increases for a 10 °C rise in temperature.
Q₁₀ = k(T+10) / k(T)
Termolecular Reaction
Chemical Kinetics & Catalysis
L²/(mol²·s)
An elementary step requiring the simultaneous collision of three species.
rate = k[A][B][C]
Threshold Energy
Chemical Kinetics & Catalysis
kJ/mol
The minimum total energy that colliding molecules must possess for the collision to be capable of reaction.
E_threshold = Ea + E_average
Transition State
Chemical Kinetics & Catalysis
kJ/mol
The highest-energy configuration along the reaction coordinate, at which bonds are partly broken and partly formed.
denoted ‡
Transition State Theory
Chemical Kinetics & Catalysis
Various
The theory that treats the activated complex as being in quasi-equilibrium with reactants and calculates rate from its decomposition frequency.
k = (k_BT/h) e^(−ΔG‡/RT)
Turnover Number
Chemical Kinetics & Catalysis
s⁻¹
The number of substrate molecules converted per catalytic site per unit time.
TON = molecules converted / active sites
Unimolecular Reaction
Chemical Kinetics & Catalysis
s⁻¹
An elementary step in which a single molecule rearranges or decomposes.
A → products, rate = k[A]
Zero-Order Reaction
Chemical Kinetics & Catalysis
mol/(L·s)
A reaction whose rate is independent of the concentration of the reactant.
[A] = [A]₀ − kt