linguistic:voice_change
Metastable mixtures

A mixture may appear to have no tendency to change, though it is not at equilibrium. For example, a mixture of SO and O is metastable as there is a kinetic barrier to formation of the product, SO.

The barrier can be overcome when a catalyst is also present in the mixture as in the contact process, but the catalyst does not affect the equilibrium concentrations.

Likewise, the formation of bicarbonate from carbon dioxide and water is very slow under normal conditions

but almost instantaneous in the presence of the catalytic enzyme carbonic anhydrase.