Mass Diffusivity (liquid)

The Mass Diffusivity of a Liquid calculator computes the diffusivity based on two liquids with two temperatures and dynamic viscosities and the diffusivity of one of them.

INSTRUCTIONS: Choose units and enter the following:

• `D_(T_1)` - the diffusion coefficient of the liquid substance 1 at Temperature `T_1`
• `D_(T_2)` - the diffusion coefficient of the substance 2 at Temperature `T_2`
• `T_1` - temperature of substance 1
• `T_2` - temperature of substance 2
• `mu_(T_1)`  - the dynamic viscosity of the substance 1
• `mu_(T_2)`  - the dynamic viscosity of the substance 2

Mass Diffusivity of a Liquid (D_T1):  The diffusivity is returned in stokes (cm²/s).

Diffusivity Equation

• Mass Diffusivity of a Liquid
• Mass Diffusivity of a Solid
• Mass Diffusivity of a Gas

The Math  / Science

The Mass Diffusivity of Liquid equation computes the mass diffusivity or diffusion coefficient for a pair of liquid substances, each with a specified temperature.  The formula for the mass diffusivity of a liquid is:

              `D_(T_1)  = D_(T_2) * (T_1 * mu_(T_2))/ (T_12 * mu_(T_1))`

where:

• `D_(T_1)` - the diffusion coefficient of the liquid substance 1 at Temperature `T_1`
• `D_(T_2)` - the diffusion coefficient of the substance 2 at Temperature `T_2`
• `T_1` - temperature of substance 1
• `T_2` - temperature of substance 2
• `mu_(T_1)`  - the dynamic viscosity of the substance 1
• `mu_(T_2)`  - the dynamic viscosity of the substance 2

The diffusivity or diffusion coefficient characterizes the relationship between the molar flux due to molecular diffusion and the gradient force of a c concentration of the material's molecules that drives diffusion.

Diffusivity is specified for one substance relative to another.  In this case there are two substances labeled substance 1 and substance 2. Each of the two substances is at a different temperature and at that temperature exhibits a characteristic of dynamic viscosity.