Bimolecular Reactions

Bimolecular Reactions


chemical reactions in which two particles participate in the elementary events—for example,

NOI + NOI → 2NO + I2

The bimolecular reaction is the most common class of chemical reactions. Both the simple (one-stage) reactions between two molecules (in the example above) and the majority of elementary reactions that are part of complex reactions belong to this class. In the case of complex reactions, atoms, radicals, and ions can enter into the bimolecular reaction in addition to molecules—for example,

ĊH3 + ĊH3 = C2H6

(recombination of free radicals). The rate of a bimolecular reaction, expressible in terms of the number of elementary reaction events per unit time per unit volume, is proportional to the frequency of collisions between the particles of the original substances (in the first example, NOI molecules). The frequency of collisions between particles is proportional to the product of their concentrations. Therefore, the rate of a bimolecular reaction is proportional to the product of the concentrations of the particles that enter into the reaction. For example, for the reaction NOI + NOI → 2NO + I2, the rate r is related to the concentration of original substances CNOI by the equation

where k is the rate constant of the reaction, which depends on the nature of the reacting particles. For the majority of reactions it increases rapidly as the temperature increases.

References in periodicals archive ?
The selections that make up the main body of the text are devoted to attosecond time-resolved spectroscopy, interfacial charge transfer states in condensed phase systems, recent advances in quantum dynamics of bimolecular reactions, and a great many other related topics.
This propagation continues until the radicals are destroyed by their mutual bimolecular reactions to give stable products or intercepted by antioxidants (Termination).
Neumark, Transition state spectroscopy of bimolecular reactions using negative ion photodetachment, Adv.
Neumark and colleagues have applied anion photodetachment techniques for the study of bimolecular reaction of the type X + HY [right arrow] XH + Y, where X and Y are halogen atoms [3, 4, 5, 6, 7, 8].
The low molar masses were attributed to bimolecular reactions inside the particles between a growing radical chain and an entering oligomeric radical into monomer-depleted reacting particles.
Relative Gibbs energies in solution through continuum models: effect of the loss of translational degrees of freedom in bimolecular reactions on Gibbs energy barriers.
Consequently, the most detailed studies of bimolecular reactions employ crossed atomic and molecular beams in vacuum.
Others describe principles of unimolecular and bimolecular reactions.
Techniques that rely on bimolecular reactions, such as Molecular Beacons, are kinetically slower and may not perform as well under ultrarapid cycling conditions, whereas techniques that rely on enzymatic degradation for signal generation, such as TagMan, may also benefit from slightly slower cycling.
Chapter 3 covers reactions in MS/MS and is followed by a chapter on applications to fundamental studies in ion chemistry, topics including unimolecular and bimolecular reactions, various reaction regions, and the thermochemistry of ions.