The Bunsen solubility coefficient or Bunsen absorption coefficient (α), named for Robert Bunsen, is one of a number of units used to describe the solubility of gases in liquids. It is frequently used in physiology.
The Bunsen coefficient is defined as the volume of gas, reduced to 273.15 K (0 °C) and 101.3 kPa, which is absorbed (under equilibrium) per unit volume of a pure liquid solvent at a specified temperature, under the partial pressure of the gas of 101.3 kPa.[1]
The units of volume are unimportant as long as they are the same, but often cm3 are used. In the SI system, the Bunsen coefficient is dimensionless.[2]