Reaction rate constant
- Reaction: A + B → C
k(T) is the reaction rate constant that depends on temperature.
[A] is the concentration of substance A in moles per volume of solution assuming the reaction is taking place throughout the volume of the solution (for a reaction taking place at a boundary it would denote something like moles of A per area).
A single-step reaction can also be written as
where Ea is the activation energy, and R is the gas constant. Since at temperature T the molecules have energies according to a Boltzmann distribution, one can expect the proportion of collisions with energy greater than Ea to vary with e−Ea/RT. A is the pre-exponential factor, or frequency factor.
- For order (m + n), the rate coefficient has units of mol1−(m+n)·L(m+n)−1·s−1
- For order zero, the rate coefficient has units of mol·L−1·s−1 (or M·s−1)
- For order one, the rate coefficient has units of s−1
- For order two, the rate coefficient has units of L·mol−1·s−1 (or M−1·s−1)
- And for order three, the rate coefficient has units of L2·mol−2·s−1 (or M−2·s−1)
Plasma and gases
Calculation of rate constants of the processes of generation and relaxation of electronically and vibrationally excited particles are of significant importance. It is used, for example, in the computer simulation of processes in plasma chemistry or microelectronics. First-principle based models should be used for such calculation. It can be done with the help of computer simulation software.
- Blauch, David. "Differential Rate Laws". Chemical Kinetics.
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