Calculate the rate of a reaction from concentration change over time.
Dividing by the stoichiometric coefficient makes the rate identical whichever species is measured. The figure obtained is an average over the interval, not an instantaneous rate. Rates fall as reactants are consumed, so an average rate over a long interval understates the initial rate substantially.
Reaction Rate
Rate = −(1/a) × Δ[A] ÷ Δt for a reactant with coefficient a
Rate = −(1/a) × Δ[A] ÷ Δt for a reactant with coefficient a Dividing by the stoichiometric coefficient makes the rate identical whichever species is measured. The figure obtained is an average over the interval, not an instantaneous rate.
Rates fall as reactants are consumed, so an average rate over a long interval understates the initial rate substantially.
This calculator takes 4 inputs: Initial concentration, Final concentration, Time elapsed, Stoichiometric coefficient. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.