Mixing ratio

In chemistry and physics, the dimensionless mixing ratio is the abundance of one component of a mixture relative to that of all other components. The term can refer either to mole ratio or mass ratio.

In atmospheric chemistry, mixing ratio usually refers to the mole ratio r_i, which is defined as the amount of a constituent n_i divided by the total amount of all other constituents in a mixture:

The mole ratio is also called amount ratio. If n_i is much smaller than n_tot (which is the case for atmospheric trace constituents), the mole ratio is almost identical to the mole fraction.

In meteorology, mixing ratio usually refers to the mass ratio ζ_i, which is defined as the mass of a constituent m_i divided by the total mass of all other constituents in a mixture:

The mass ratio of water vapor in air can be used to describe humidity.

Two binary solutions of different compositions or even two pure components can be mixed with various mixing ratios by masses, moles, or volumes.

The mass fraction of the resulting solution from mixing solutions with masses m_1,2 and mass fractions w₁ and w₂ is given by:

${\displaystyle w={\frac {w_{1}m_{1}+w_{2}m_{1}r_{m}}{m_{1}+m_{1}r_{m}}}}$ where m₁ can be simplified from numerator and denominator

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