Determine the rate constant for zero, first or second-order kinetics.
Each reaction order has its own integrated rate law and its own units for k. Only first-order reactions have a concentration-independent half-life, which is why radioactive decay is described so simply. Fitting data to the wrong order gives a k that drifts with concentration, which is itself the diagnostic that the order is wrong.
Rate Constant
Zero: k = ([A]₀−[A])/t; first: k = ln([A]₀/[A])/t; second: k = (1/[A] − 1/[A]₀)/t
Zero: k = ([A]₀−[A])/t; first: k = ln([A]₀/[A])/t; second: k = (1/[A] − 1/[A]₀)/t Each reaction order has its own integrated rate law and its own units for k. Only first-order reactions have a concentration-independent half-life, which is why radioactive decay is described so simply.
Fitting data to the wrong order gives a k that drifts with concentration, which is itself the diagnostic that the order is wrong.
This calculator takes 4 inputs: Initial concentration, Concentration after time t, Time elapsed, Reaction order. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.