How does the kinetic isotope effect the rate of a chemical reaction?

thefern

It depends on the mass of the atoms that are being changed. Potential energy is energy that is being stored, and kinetic energy is energy that is being 'released' within a reaction. An isotopic change for a C-12 atom into an (let's say) C-13 atom is going to be alot lower than that of a light atom like He, or H into something much heavier. Aug 22 06, 10:26 PM

zbeckabee

The kinetic isotope effect is a variation in the rate of a chemical reaction when an atom in one of the reactants is replaced by one of its isotopes. An isotopic substitution will greatly modify the reaction rate when the isotopic replacement is in a chemical bond that is broken or formed. In such a case, the rate change is termed a primary isotope effect. When the substitution is not involved in the bond that is breaking or forming, one may still observe a smaller rate change, termed a secondary isotope effect. Thus, the magnitude of the kinetic isotope effect can be used to elucidate the reaction mechanism. Isotope effects are most easily observed when they occur in the rate-determining step of a reaction. If other steps are partially rate-determining, the effect of isotopic substitution will be masked. http://search.com.com/reference/Kinetic_isotope_effect Aug 23 06, 9:52 AM