I recorded the concentrations of a product during a reaction. There was an enzyme producing bacteria as catalyzer. Then I plotted the concentration changes versus time and fitted a modified logistic function (based on the related literature; 1st order kinetics) to the plotted data. I found then the rate constant (K) from the fitted function. It was 1.68 1/h. Can it be bigger than 1? if so, what does it mean?
Without seeing the equation you used, I don't think there is any reason why the rate constant for the reaction should be limited to 1. It's probably just a coincidence that it came out a bit over 1 in your experiment.
A 1st order rate law is -d[S]/dt = d[P]/dt = k[S]. k can have any positive value. You can measure k from the initial rate of the reaction, before depletion of the substrate and accumulation of the product starts to slow down the reaction rate.
In your experiment, the reaction is actually 2nd order because you have to consider the enzyme concentration: d[P]/dt = k[E][S] for the initial velocity.
Without seeing the equation you used, I don't think there is any reason why the rate constant for the reaction should be limited to 1. It's probably just a coincidence that it came out a bit over 1 in your experiment.
A 1st order rate law is -d[S]/dt = d[P]/dt = k[S]. k can have any positive value. You can measure k from the initial rate of the reaction, before depletion of the substrate and accumulation of the product starts to slow down the reaction rate.
In your experiment, the reaction is actually 2nd order because you have to consider the enzyme concentration: d[P]/dt = k[E][S] for the initial velocity.
The rate constant of a reaction is its intrinsic rate when the concentrations of all its reactants is unity. Therefor, it can have any positive value (i.e. more than zero) and there is no limiting value like 1. It can have very large values for a extremely fast reactions.
There is no limitation of the value of K, the order of reaction is a function of concentration and not K
Actually, the upper limit to chemical rate constants - in solution anyway - is the molecular diffusion rate which is about 10^9 sec^-1.
I don't see any reason to limit your constant to 1. But I can perhaps give a more precise answer by viewing the details og the fitting ([email protected])
The above comment refers to bimolecular reactions and therefore it has units of M^-1 sec^-1. M Eigen made pioneering studies on recombination rates of acids and bases in solution. His value for proton transfer at room temperature was 10^10 M^-1 sec^-1.
The question is meaningless because no dimension of the number is given such as sec-1, if the number is < 1 sec-1 the question is meaningful, for instance the rate constant could be k = 0.134 sec-1. Rate constants are referred to in small k. Your large K suspects that you may confuse rate constants with equilibrium constants, the nomenclature being capital K.
Rate constant is denoted in lowercase k and equilibrium constant is denoted in uppercase K.
Hope you are thinking about k. It can be greater than 1 regardless the order.
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