What this calculator does
Diffusion coefficient (Stokes-Einstein) works out diffusion rate of a spherical particle in a fluid, from its size, viscosity and temperature. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| Temperature (K) | A number, measured in K. Starts at 298.15. |
| Fluid viscosity η (Pa·s) | A number, measured in Pa·s. Starts at 0.00089. |
| Particle radius (nm) | A number, measured in nm. Starts at 5. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with temperature
Every other input is held at the calculator’s starting values while temperature varies. Select any row to load that scenario into the calculator.
| Temperature (K) | Diffusion coefficient D | Diffusion coefficient D | Particle radius used |
|---|---|---|---|
| 149 | 2.4525e-11 m²/s | 2.4525e-7 cm²/s | 5.00 nm |
| 224 | 3.6870e-11 m²/s | 3.6870e-7 cm²/s | 5.00 nm |
| 298 | 4.9050e-11 m²/s | 4.9050e-7 cm²/s | 5.00 nm |
| 447 | 7.3575e-11 m²/s | 7.3575e-7 cm²/s | 5.00 nm |
| 596 | 9.8100e-11 m²/s | 9.8100e-7 cm²/s | 5.00 nm |
| 894 | 1.4715e-10 m²/s | 1.4715e-6 cm²/s | 5.00 nm |