Understanding Rate Constants
In chemical kinetics, the rate constant (often denoted by k) is a crucial proportionality constant that relates the rate of a chemical reaction to the concentration of the reactants. It quantifies how fast a reaction proceeds. The value of the rate constant is dependent on factors such as temperature, pressure, and the presence of a catalyst, but it is independent of reactant concentrations.
The rate law for a general reaction: aA + bB → cC + dD can be expressed as: Rate = k[A]m[B]n where [A] and [B] are the concentrations of reactants A and B, respectively, and m and n are the reaction orders with respect to A and B. The rate constant, k, is the proportionality constant in this equation.
The units of the rate constant depend on the overall order of the reaction. For example:
- For a zero-order reaction (m+n=0), the rate constant units are M/s (or mol L-1 s-1).
- For a first-order reaction (m+n=1), the rate constant units are 1/s (or s-1).
- For a second-order reaction (m+n=2), the rate constant units are 1/(M·s) (or L mol-1 s-1).
This calculator helps you determine the rate constant (k) given the initial rate of a reaction and the concentrations of the reactants, assuming you know the reaction orders.
Rate Constant Calculator
Enter the following values to calculate the rate constant (k):