"In chemistry, transition state theory (TST) explains the reaction rates of elementary chemical reactions."
A theory that explains reaction rates in terms of the activation energy required for reactants to reach a transition state.
Activation Energy: The energy required for a chemical reaction to proceed.
Chemical Equilibrium: The point at which the concentration of reactants and products in a chemical reaction is balanced.
Reaction Rates: The rate at which a chemical reaction occurs, typically measured in terms of concentration change in the reactants and/or products over time.
Chemical Kinetics: The study of chemical reactions and how they occur, including the factors that influence their rates.
Rate Laws: Mathematical equations that describe the relationship between reaction rates and the concentration of reactants.
Reaction Mechanisms: Detailed descriptions of the steps involved in a chemical reaction, including the intermediates and transition states.
Reaction Dynamics: The study of the behavior of molecules during a chemical reaction, particularly in relation to their energy.
Elementary Reactions: The individual steps in a reaction mechanism that involve only a single collision between molecules.
Transition States: The points of highest energy in a reaction mechanism, where the reactants are most likely to transform into products.
Gibbs Free Energy: A thermodynamic parameter that determines whether a chemical reaction is spontaneous or requires energy input.
Enzyme Kinetics: The study of how enzymes catalyze chemical reactions and the factors that influence their rates.
Solvent Effects: The influence of the solvent on the rate of a chemical reaction, particularly in relation to the solvation of reactants and/or products.
Temperature Effects: The impact of temperature on the rate of a chemical reaction, including how increasing or decreasing the temperature affects the activation energy and reaction rate.
Reaction Coordinate Diagrams: Graphical representations of the energy changes that occur during a chemical reaction, including the activation energy and transition state.
Activation Entropy: The contribution of entropy (the degree of disorder) to the activation energy of a chemical reaction.
Classical Transition State Theory: This theory assumes that the reactants must overcome a high-energy barrier, which is the transition state, to form the products. The rate of the reaction is proportional to the product of the frequency factor and the exponential of the negative activation energy.
Transition State Theory with Solvent Effects: This theory takes into account the effects of a solvent on the transition state. The activation energy may be affected by the solvent which usually raises the barrier as additional energy is required to overcome the solvent cage.
Quantum Transition State Theory: This theory combines principles of quantum mechanics with classical transition state theory. This theory considers nuclear motions using quantum mechanics to determine the rate of reaction.
TST with tunneling: This theory considers the probability of a reactant tunneling through the potential barrier instead of climbing over the barrier. This theory becomes relevant when there is a wide enough barrier that allows tunneling through the barrier.
Dynamic TST is an extension of the traditional transition state theory that examines how the transition state changes during a reaction: It takes into consideration the vibrational modes of the molecule and their distribution in energy.
"The theory assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated transition state complexes."
"TST is used primarily to understand qualitatively how chemical reactions take place."
"It has been successful in calculating the standard enthalpy of activation (ΔH‡), the standard entropy of activation (ΔS‡ or Δ‡Sɵ), and the standard Gibbs energy of activation (ΔG‡ or Δ‡Gɵ) for a particular reaction if its rate constant has been experimentally determined."
"This theory was developed simultaneously in 1935 by Henry Eyring, then at Princeton University, and by Meredith Gwynne Evans and Michael Polanyi of the University of Manchester."
"TST is also referred to as 'activated-complex theory', 'absolute-rate theory', and 'theory of absolute reaction rates'."
"The Arrhenius equation derives from empirical observations and ignores any mechanistic considerations, such as whether one or more reactive intermediates are involved in the conversion of a reactant to a product."
"The pre-exponential factor (A) and the activation energy (Ea)."
"TST, which led to the Eyring equation, successfully addresses these two issues."
"46 years elapsed between the publication of the Arrhenius rate law, in 1889, and the Eyring equation derived from TST, in 1935."
"The calculation of absolute reaction rates requires precise knowledge of potential energy surfaces."
"ΔH‡ is the difference between the enthalpy of the transition state and that of the reactants."
"TST successfully addresses the two issues associated with the Arrhenius rate law, the pre-exponential factor (A) and the activation energy (Ea)."
"The Arrhenius equation derives from empirical observations."
"The Arrhenius equation ignores any mechanistic considerations."
"TST has been less successful in its original goal of calculating absolute reaction rate constants."
"TST assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated transition state complexes."
"It has been successful in calculating the standard enthalpy of activation (ΔH‡), the standard entropy of activation (ΔS‡ or Δ‡Sɵ), and the standard Gibbs energy of activation (ΔG‡ or Δ‡Gɵ) for a particular reaction."
"The ‡ notation refers to the value of interest at the transition state."
"Many scientists and researchers contributed significantly to the development of the theory."