# Learn how To calculate Molecular Diffusion Coefficeint - Tutorial

## Learn how To calculate Molecular Diffusion Coefficeint - Definition, Formula, Example

##### Definition:

Molecular diffusion is the process of diffusing between adjacent layers of fluid whereby solutes are moved at the microscopic level due to difference in the solute absorption within the fluid parts.

##### Formula: ###### Where,

C = concentration at z, Co = initial concentration, z = distance from the source, p= porosity, D = coefficient of molecular diffusion, t= tortuosity, t = time.

##### Example:

Find the distance by the Molecular Diffusion method with a normalized concentration of 1.0e-9 and diffusion of 1.e-5 cm2/sec withing the time period of 1000 years and the porosity and tortuosity of the diffusion is 0.20,0.8.

##### Given,

Normalized Concentration= 1.0e-9 time = 1000 years Diffusion = 1.e-5 cm2/sec Porosity = 0.20 Tortuosity = 0.8

Distance (feet)

##### Solution:

Substitute the given values in the formula:, Z = -2√(0.20*1e-5*0.80*1000) * [erf-1(2 - 1.0e-9)] Z = -2√(54.3493)* 4.3201 Z = -2*7.3721*4.3201 Z = 63.69770 feet