absorption the assimilation of a chemical (usually a gas or liquid) into a liquid or porous solid.

adsorption the deposition of a chemical (usually a gas or liquid) onto the surface of a solid. Charcoal in an aquarium filter or in a tap water purifier adsorbs organic chemicals from water.

azeotrope a mixture of two or more components such that the composition of the liquid is the same as the vapor. Not all mixtures form an azeotrope. Water and ethanol form an azeotrope at about 95% water.

base units the units of the base dimensions, which are length, time, mass, temperature, amount, electric charge, and luminous intensity. In the inks SI system, the base units are meter, second, kilogram, kelvin (or Celsius), mole, ampere, and candela.

batch reactor a vessel into which reactants are loaded, induced to react (by increasing the temperature, and/or increasing the pressure, and/or adding a catalyst), then discharged. A batch reactor is not at steady state, although its contents may approach equilibrium. A batch reactor is inherently noncontinuous but can be integrated into a continuous process if preceded by a hold-up tank and followed by a surge tank. A crock pot is a batch reactor.

biochemical engineering the design and nalysis of processes based on biological reactions, for example to produce a drug or destroy a pollutant.