Whether it is through the collision theory, transition theory, or just common sense, chemical reactions are typically expected to proceed faster at higher temperatures and slower at lower temperatures. By 1890 it was common knowledge that higher temperatures speed up reactions, often doubling the rate for a 10 degree rise, but the reasons for this were not clear. Finally, in 1899, the Swedish chemist Svante Arrhenius (1859-1927) combined the concepts of activation energy and the Boltzmann distribution law into one of the most important relationships in physical chemistry. The "Arrhenius Equation" was physical justification and interpretation. Arrhenius performed experiments that correlated chemical reaction rate constants with temperature. After observing that many chemical reaction rates depended on the temperature, Arrhenius developed this equation to characterize the temperature dependent reactions: Lecture114: Arrhenius Equation 2: Arrhenius Equation Where: k: Chemical reaction rate constant In unit of s-1(for 1st order rate constant) or M-1s-1(for 2nd order rate constant) A: The pre-exponential factor or frequency factor Specifically relates to molecular collision Deals with the frequency of molecules that collide in the correct orientation and with enough energy to initiate a reaction. It is a factor that is determined experimentally, as it varies with different reactions. In unit of L mol-1s-1 or M-1s-1(for 2nd rate constant) and s-1(for 1st order rate constant) Because frequency factor A is related to molecular collision, it is temperature dependent
Whether it is through the collision theory, transition theory, or just common sense, chemical reactions are typically expected to proceed faster at higher temperatures and slower at lower temperatures. By 1890 it was common knowledge that higher temperatures speed up reactions, often doubling the rate for a 10 degree rise, but the reasons for this were not clear. Finally, in 1899, the Swedish chemist Svante Arrhenius (1859-1927) combined the concepts of activation energy and the Boltzmann distribution law into one of the most important relationships in physical chemistry. The "Arrhenius Equation" was physical justification and interpretation. Arrhenius performed experiments that correlated chemical reaction rate constants with temperature. After observing that many chemical reaction rates depended on the temperature, Arrhenius developed this equation to characterize the temperature dependent reactions: Lecture114: Arrhenius Equation 2: Arrhenius Equation Where: k: Chemical reaction rate constant In unit of s-1(for 1st order rate constant) or M-1s-1(for 2nd order rate constant) A: The pre-exponential factor or frequency factor Specifically relates to molecular collision Deals with the frequency of molecules that collide in the correct orientation and with enough energy to initiate a reaction. It is a factor that is determined experimentally, as it varies with different reactions. In unit of L mol-1s-1 or M-1s-1(for 2nd rate constant) and s-1(for 1st order rate constant) Because frequency factor A is related to molecular collision, it is temperature dependent
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