Inatmospheric chemistry, mixing ratio usually refers to the mole ratiori, which is defined as the amount of a constituent ni divided by the total amount of all other constituents in a mixture:
The mole ratio is also called amount ratio.[2]Ifni is much smaller than ntot (which is the case for atmospheric trace constituents), the mole ratio is almost identical to the mole fraction.
Inmeteorology, mixing ratio usually refers to the mass ratio of water , which is defined as the mass of water divided by the mass of dry air () in a given air parcel:[3]
The unit is typically given in . The definition is similar to that of specific humidity.
The condition to get a partially ideal solution on mixing is that the volume of the resulting mixture V to equal double the volume Vs of each solution mixed in equal volumes due to the additivity of volumes. The resulting volume can be found from the mass balance equation involving densities of the mixed and resulting solutions and equalising it to 2:
implies
Of course for real solutions inequalities appear instead of the last equality.
Mixtures of different solvents can have interesting features like anomalous conductivity (electrolytic) of particular lyonium ions and lyate ions generated by molecular autoionization of protic and aprotic solvents due to Grotthuss mechanism of ion hopping depending on the mixing ratios. Examples may include hydronium and hydroxide ions in water and water alcohol mixtures, alkoxonium and alkoxide ions in the same mixtures, ammonium and amide ions in liquid and supercritical ammonia, alkylammonium and alkylamide ions in ammines mixtures, etc....