Autocatalysis
Catalysis of a reaction by one of its own products.
Unit
Dimensionless
In depth
An autocatalytic reaction starts slowly, accelerates as catalytic product accumulates, then slows again as reactant is exhausted, producing a distinctive S-shaped concentration curve. The positive feedback can drive oscillating reactions and, in extreme cases, runaway behaviour.
Examples in the real world
Mn²⁺ catalysing the permanganate–oxalate titration, whose first drop decolourises slowly and later drops instantly.